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ltc1992 family 1992fa typical a pplica t ion fea t ures descrip t ion low power, fully differential input/output amplifier/driver family the ltc ? 1992 product family consists of five fully differen- tial, low power amplifiers. the ltc1992 is an unconstrained fully differential amplifier. the ltc1992-1, ltc1992-2, ltc1992-5 and ltc1992-10 are fixed gain blocks (with gains of 1, 2, 5 and 10 respectively) featuring precision on-chip resistors for accurate and ultrastable gain. all of the ltc1992 parts have a separate internal common mode feedback path for outstanding output phase balancing and reduced second order harmonics. the v ocm pin sets the output common mode level independent of the input common mode level. this feature makes level shifting of signals easy. the amplifiers differential inputs operate with signals ranging from rail-to-rail with a common mode level from the negative supply up to 1.3v from the positive supply. the differential input dc offset is typically 250v. the rail-to-rail outputs sink and source 10ma. the ltc1992 is stable for all capacitive loads up to 10,000pf. the ltc1992 can be used in single supply applications with supply voltages as low as 2.7v. it can also be used with dual supplies up to 5v. the ltc1992 is available in an 8-pin msop package. single-supply, single-ended to differential conversion a pplica t ions n adjustable gain and fixed gain blocks of 1, 2, 5 and 10 n 0.3% (max) gain error from C40c to 85c n 3.5ppm/c gain temperature coefficient n 5ppm gain long term stability n fully differential input and output n c load stable up to 10,000pf n adjustable output common mode voltage n rail-to-rail output swing n low supply current: 1ma (max) n high output current: 10ma (min) n specified on a single 2.7v to 5v supply n dc offset voltage <2.5mv (max) n available in 8-lead msop package n differential driver/receiver n differential amplification n single-ended to differential conversion n level shifting n trimmed phase response for multichannel systems l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. ? ? + + 5v 5v ltc1992 3 6 v ocm v mid 0v 2.5v 0v v in 0.01f 1992 ta01a 4 5 2 7 8 1 10k 10k 10k 10k 5v 0v 5v ?5v 2.5v input signal from a 5v system output signal from a single-supply system v in (5v/div) +out ?out (2v/div) 5v 0v ?5v 5v 0v 1992 ta01b
ltc1992 family 1992fa a bsolu t e maxi m u m r a t ings total supply voltage (+v s to Cv s ) ............................. 12v maximum voltage on any pin ................ (Cv s C 0.3v) v pin (+v s + 0.3v) output short-circuit duration (note 3) ............ indefinite operating temperature range (note 5) ltc1992cms8/ltc1992-xcms8/ l t c1992ims8/ltc1992-xims8 ...........C40c to 85c l t c1992hms8/ltc1992-xhms8 ...... C40c to 125c (note 1) p in c on f igura t ion o r d er i n f or m a t ion lead free finish tape and reel part marking* package description temperature range ltc1992cms8#pbf ltc1992cms8#trpbf ltyu 8-lead plastic msop C40c to 85c ltc1992ims8#pbf ltc1992ims8#trpbf ltyu 8-lead plastic msop C40c to 85c ltc1992hms8#pbf ltc1992hms8#trpbf ltyu 8-lead plastic msop C40c to 125c ltc1992-1cms8#pbf ltc1992-1cms8#trpbf ltacj 8-lead plastic msop C40c to 85c ltc1992-1ims8#pbf ltc1992-1ims8#trpbf ltacj 8-lead plastic msop C40c to 85c ltc1992-1hms8#pbf ltc1992-1hms8#trpbf ltacj 8-lead plastic msop C40c to 125c ltc1992-2cms8#pbf ltc1992-2cms8#trpbf ltyv 8-lead plastic msop C40c to 85c ltc1992-2ims8#pbf ltc1992-2ims8#trpbf ltyv 8-lead plastic msop C40c to 85c ltc1992-2hms8#pbf ltc1992-2hms8#trpbf ltyv 8-lead plastic msop C40c to 125c ltc1992-5cms8#pbf ltc1992-5cms8#trpbf ltack 8-lead plastic msop C40c to 85c ltc1992-5ims8#pbf ltc1992-5ims8#trpbf ltack 8-lead plastic msop C40c to 85c ltc1992-5hms8#pbf ltc1992-5hms8#trpbf ltack 8-lead plastic msop C40c to 125c ltc1992-10cms8#pbf ltc1992-10cms8#trpbf ltacl 8-lead plastic msop C40c to 85c ltc1992-10ims8#pbf ltc1992-10ims8#trpbf ltacl 8-lead plastic msop C40c to 85c ltc1992-10hms8#pbf ltc1992-10hms8#trpbf ltacl 8-lead plastic msop C40c to 125c consult ltc marketing for parts specified with wider operating temperature ranges. *the temperature grade is identified by a label on the shipping container. consult ltc marketing for information on non-standard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ specified temperature range (note 6) ltc1992cms8/ltc1992-xcms8/ ltc1992ims8/ltc1992-xims8 ........... C40c to 85c l t c1992hms8/ltc1992-xhms8 ...... C40c to 125c storage temperature range ................. C65c to 150c lead temperature (soldering, 10 sec)................... 300c ltc1992 ltc1992-x 1 2 3 4 ?in v ocm +v s +out 8 7 6 5 +in v mid ?v s ?out top view ms8 package 8-lead plastic msop + + ? ? t jmax = 150c, ja = 250c/w 1 2 3 4 ?in v ocm +v s +out 8 7 6 5 +in v mid ?v s ?out top view ms8 package 8-lead plastic msop + + ? ? t jmax = 150c, ja = 250c/w
ltc1992 family 1992fa e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). specifications applicable to all parts in the ltc1992 family. symbol parameter conditions all c and i grade all h grade units min typ max min typ max v s supply voltage range l 2.7 11 2.7 11 v i s supply current v s = 2.7v to 5v v s = 5v l l 0.65 0.75 0.7 0.8 1.0 1.2 1.2 1.5 0.65 0.8 0.7 0.9 1.0 1.5 1.2 1.8 ma ma ma ma v osdiff differential offset voltage (input referred) (note 7) v s = 2.7v v s = 5v v s = 5v l l l 0.25 0.25 0.25 2.5 2.5 2.5 0.25 0.25 0.25 4 4 4 mv mv mv ?v osdiff /?t differential offset voltage drift (input referred) (note 7) v s = 2.7v v s = 5v v s = 5v l l l 10 10 10 10 10 10 v/c v/c v/c psrr power supply rejection ratio (input referred) (note 7) v s = 2.7v to 5v l 75 80 72 80 db gcm common mode gain(v outcm /v ocm ) common mode gain error output balance (?v outcm /(?v outdiff ) v outdiff = C2v to +2v l l l 1 0.1 C85 0.3 C60 1 0.1 C85 0.35 C60 % db v oscm common mode offset voltage (v outcm C v ocm ) v s = 2.7v v s = 5v v s = 5v l l l 0.5 1 2 12 15 18 0.5 1 2 15 17 20 mv mv mv ?v oscm /?t common mode offset voltage drift v s = 2.7v v s = 5v v s = 5v l l l 10 10 10 10 10 10 v/c v/c v/c v outcmr output signal common mode range (voltage range for the v ocm pin) l (Cv s ) + 0.5v (+v s ) C 1.3v (Cv s ) + 0.5v (+v s ) C 1.3v v r invocm input resistance, v ocm pin l 500 500 m i bvocm input bias current, v ocm pin v s = 2.7v to 5v l 2 2 pa v mid voltage at the v mid pin l 2.44 2.50 2.56 2.43 2.50 2.57 v v out output voltage, high (note 2) v s = 2.7v, load = 10k v s = 2.7v, load = 5ma v s = 2.7v, load = 10ma l l l 2.60 2.50 2.29 2.69 2.61 2.52 2.60 2.50 2.29 2.69 2.61 2.52 v v v output voltage, low (note 2) v s = 2.7v, load = 10k v s = 2.7v, load = 5ma v s = 2.7v, load = 10ma l l l 0.02 0.10 0.20 0.10 0.25 0.35 0.02 0.10 0.20 0.10 0.25 0.41 v v v output voltage, high (note 2) v s = 5v, load = 10k v s = 5v, load = 5ma v s = 5v, load = 10ma l l l 4.90 4.85 4.75 4.99 4.90 4.81 4.90 4.80 4.70 4.99 4.90 4.81 v v v output voltage, low (note 2) v s = 5v, load = 10k v s = 5v, load = 5ma v s = 5v, load = 10ma l l l 0.02 0.10 0.20 0.10 0.25 0.35 0.02 0.10 0.20 0.10 0.30 0.42 v v v output voltage, high (note 2) v s = 5v, load = 10k v s = 5v, load = 5ma v s = 5v, load = 10ma l l l 4.90 4.85 4.65 4.99 4.89 4.80 4.85 4.80 4.60 4.99 4.89 4.80 v v v output voltage, low (note 2) v s = 5v, load = 10k v s = 5v, load = 5ma v s = 5v, load = 10ma l l l C4.99 C4.90 C4.80 C4.90 C4.75 C4.65 C4.98 C4.90 C4.80 C4.85 C4.75 C4.55 v v v
ltc1992 family 1992fa e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). specifications applicable to all parts in the ltc1992 family. symbol parameter conditions all c and i grade all h grade units min typ max min typ max i sc output short-circuit current sourcing (notes 2,3) v s = 2.7v, v out =1.35v v s = 5v, v out = 2.5v v s = 5v, v out = 0v l l l 20 20 20 30 30 30 20 20 20 30 30 30 ma ma ma output short-circuit current sinking (notes 2,3) v s = 2.7v, v out =1.35v v s = 5v, v out = 2.5v v s = 5v, v out = 0v l l l 13 13 13 30 30 30 13 13 13 30 30 30 ma ma ma a vol large-signal voltage gain l 80 80 db the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). specifications applicable to the ltc1992 only. symbol parameter conditions ltc1992cms8 ltc1992ism8 ltc1992hms8 units min typ max min typ max i b input bias current v s = 2.7v to 5v l 2 250 2 400 pa i os input offset current v s = 2.7v to 5v l 0.1 100 0.1 150 pa r in input resistance l 500 500 m c in input capacitance l 3 3 pf e n input referred noise voltage density f = 1khz 35 35 nv/ hz i n input noise current density f = 1khz 1 1 fa/hz v incmr input signal common mode range l (Cv s ) C 0.1v (+v s ) C 1.3v (Cv s ) C 0.1v (+v s ) C 1.3v v cmrr common mode rejection ratio (input referred) v incm = C0.1v to 3.7v l 69 90 69 90 db sr slew rate (note 4) l 0.5 1.5 0.5 1.5 v/s gbw gain-bandwidth product (f test = 100khz) t a = 25c ltc1992cms8 ltc1992ims8/ ltc1992hms8 l l 3.0 2.5 1.9 3.2 3.0 3.5 4.0 4.0 3.0 1.9 3.2 3.5 4.0 mhz mhz mhz
ltc1992 family 1992fa e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). typical values are at t a = 25c. specifications apply to the ltc1992-1 only. symbol parameter conditions ltc1992-1cms8 ltc1992-1ism8 ltc1992-1hms8 units min typ max min typ max g diff differential gain differential gain error differential gain nonlinearity differential gain temperature coefficient l l 1 0.1 50 3.5 0.3 1 0.1 50 3.5 0.35 v/v % ppm ppm/c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins l 22.5 30 37.5 22 30 38 k v incmr input signal common mode range v s = 5v C0.1v to 4.9v C0.1v to 4.9v v cmrr common mode rejection ratio (amplifier input referred) (note 7) v incm = C0.1v to 3.7v l 55 60 55 60 db sr slew rate (note 4) l 0.5 1.5 0.5 1.5 v/s gbw gain-bandwidth product f test = 180khz 3 3 mhz the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). typical values are at t a = 25c. specifications apply to the ltc1992-2 only. symbol parameter conditions ltc1992-2cms8 ltc1992-2ism8 ltc1992-2hms8 units min typ max min typ max g diff differential gain differential gain error differential gain nonlinearity differential gain temperature coefficient l l 2 0.1 50 3.5 0.3 2 0.1 50 3.5 0.35 v/v % ppm ppm/c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins l 22.5 30 37.5 22 30 38 k v incmr input signal common mode range v s = 5v C0.1v to 4.9v C0.1v to 4.9v v cmrr common mode rejection ratio (amplifier input referred) (note 7) v incm = C0.1v to 3.7v l 55 60 55 60 db sr slew rate (note 4) l 0.7 2 0.7 2 v/s gbw gain-bandwidth product f test = 180khz 4 4 mhz
ltc1992 family 1992fa e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). typical values are at t a = 25c. specifications apply to the ltc1992-5 only. symbol parameter conditions ltc1992-5cms8 ltc1992-5ism8 ltc1992-5hms8 units min typ max min typ max g diff differential gain differential gain error differential gain nonlinearity differential gain temperature coefficient l l 5 0.1 50 3.5 0.3 5 0.1 50 3.5 0.35 v/v % ppm ppm/c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins l 22.5 30 37.5 22 30 38 k v incmr input signal common mode range v s = 5v C0.1v to 3.9v C0.1v to 3.9v v cmrr common mode rejection ratio (amplifier input referred) (note 7) v incm = C0.1v to 3.7v l 55 60 55 60 db sr slew rate (note 4) l 0.7 2 0.7 2 v/s gbw gain-bandwidth product f test = 180khz 4 4 mhz the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. +v s = 5v, Cv s = 0v, v incm = v outcm = v ocm = 2.5v, unless otherwise noted. v ocm is the voltage on the v ocm pin. v outcm is defined as (+v out + Cv out )/2. v incm is defined as (+v in + Cv in )/2. v indiff is defined as (+v in C Cv in ). v outdiff is defined as (+v out C Cv out ). typical values are at t a = 25c. specifications apply to the ltc1992-10 only. symbol parameter conditions ltc1992-10cms8 ltc1992-10ism8 ltc1992-10hms8 units min typ max min typ max g diff differential gain differential gain error differential gain nonlinearity differential gain temperature coefficient l l 10 0.1 50 3.5 0.3 10 0.1 50 3.5 0.35 v/v % ppm ppm/c e n input referred noise voltage density (note 7) f = 1khz 45 45 nv/ hz r in input resistance, single-ended +in, Cin pins l 11.3 15 18.8 11 15 19 k v incmr input signal common mode range v s = 5v C0.1v to 3.8v C0.1v to 3.8v v cmrr common mode rejection ratio (amplifier input referred) (note 7) v incm = C0.1v to 3.7v l 55 60 55 60 db sr slew rate (note 4) l 0.7 2 0.7 2 v/s gbw gain-bandwidth product f test = 180khz 4 4 mhz note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: output load is connected to the midpoint of the +v s and Cv s potentials. measurement is taken single-ended, one output loaded at a time. note 3: a heat sink may be required to keep the junction temperature below the absolute maximum when the output is shorted indefinitely. note 4: differential output slew rate. slew rate is measured single ended and doubled to get the listed numbers. note 5: the ltc1992c/ltc1992-xc/ltc1992i/ltc1992-xi are guaranteed functional over an operating temperature of C40c to 85c. the ltc1992h/ltc1992-xh are guaranteed functional over the extended operating temperature of C40c to 125c. note 6: the ltc1992c/ltc1992-xc are guaranteed to meet the specified performance limits over the 0c to 70c temperature range and are designed, characterized and expected to meet the specified performance limits over the C40c to 85c temperature range but are not tested or qa sampled at these temperatures. the ltc1992i/ltc1992-xi are guaranteed to meet the specified performance limits over the C40c to 85c temperature range. the ltc1992h/ltc1992-xh are guaranteed to meet the specified performance limits over the C40c to 125c temperature range. note 7: differential offset voltage, differential offset voltage drift, cmrr, noise voltage density and psrr are referred to the internal amplifiers input to allow for direct comparison of gain blocks with discrete amplifiers.
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics common mode offset voltage vs v ocm voltage common mode offset voltage vs v ocm voltage common mode offset voltage vs v ocm voltage output voltage swing vs output load, v s = 2.7v output voltage swing vs output load, v s = 5v supply current vs supply voltage differential input offset voltage vs temperature (note 7) common mode offset voltage vs temperature applicable to all parts in the ltc1992 family. total supply voltage (v) 0 supply current (ma) 0.6 0.8 1.0 8 1992 g01 0.4 0.2 0.5 0.7 0.9 0.3 0.1 0 21 43 6 7 9 5 10 125c 85c 25c ?40c temperature (c) ?40 0.6 0.4 0.2 0 ?0.2 ?0.4 ?0.6 ?0.8 1992 g02 25 85 125 differential v os (mv) v incm = 0v v ocm = 0v v s = 1.35v v s = 2.5v v s = 5v temperature (c) ?40 ?5 common mode v os (mv) ?4 ?2 ?1 0 85 4 1992 g03 ?3 25 125 1 2 3 v incm = 0v v ocm = 0v v s = 5v v s = 1.35v v s = 2.5v v ocm voltage (v) 0 ?20 v ocm v os (mv) ?15 ?5 0 5 0.6 1.2 1.5 2.7 1992 g04 ?10 0.3 0.9 1.8 2.1 2.4 125c 85c 25c ?40c +v s = 2.7v ?v s = 0v v incm = 1.35v v ocm voltage (v) 0 v ocm v os (mv) ?5 0 5 4 1992 g05 ?10 ?15 ?20 0.5 1 1.5 2 2.5 3 3.5 4.5 5 +v s = 5v ?v s = 0v v incm = 2.5v 125c 85c 25c ?40c v ocm voltage (v) ?5 v ocm v os (mv) ?5 0 5 3 1992 g06 ?10 ?15 ?20 ?4 ?3 ?2 ?1 0 1 2 4 5 +v s = 5v ?v s = ?5v v incm = 0v 125c 85c 25c ?40c load current (ma) ?20 +swing (v) ?swing (v) 2.50 2.60 20 1992 g07 2.40 2.30 ?10 0 10 ?15 ?5 5 15 2.70 2.45 2.55 2.35 2.65 0.4 0.6 0.2 0 0.8 0.3 0.5 0.1 0.7 ?40c ?40c 125c 125c 25c 85c 85c 25c load current (ma) ?20 20 4.50 +swing (v) ?swing (v) 4.55 4.65 4.70 4.75 5.00 4.85 ?10 0 1992 g08 4.60 4.90 4.95 4.80 0 0.1 0.3 0.4 0.5 1.0 0.7 0.2 0.8 0.9 0.6 10 15 ?15 ?5 5 ?40c ?40c 125c 125c 85c 85c 25c 25c
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics differential gain vs time (normalized to t = 0) input common mode overdrive recovery (expanded view) input common mode overdrive recovery (detailed view) output overdrive recovery (expanded view) output overdrive recovery (detailed view) output voltage swing vs output load, v s = 5v v ocm input bias current vs v ocm voltage differential input offset voltage vs time (normalized to t = 0) applicable to all parts in the ltc1992 family. load current (ma) ?20 4.4 +swing (v) ?swing (v) 4.5 4.6 4.7 4.8 ?10 0 10 20 ?15 ?5 5 15 1992 g09 4.9 5.0 ?5.0 ?4.8 ?4.6 ?4.4 ?4.2 ?4.0 ?3.8 ?40c ?40c 125c 125c 85c 25c 85c 25c v ocm voltage (v) 0 0.5 1 v ocm input bias current (a) 1.5 2 2.5 3 3.5 4 4.5 5 1992 g10 100e-15 10e-9 1e-9 100e-12 10e-12 1e-12 +v s = 5v ?v s = 0v v incm = 2.5v 125c 85c 25c ?40c time (hours) 100 80 60 40 20 0 ?20 ?40 ?60 ?80 ?100 delta v os (v) 1992 g11 0 400 800 1200 1600 2000 temp = 35c time (hours) 10 8 6 4 2 0 ?2 ?4 ?6 ?8 ?10 delta gain (ppm) 1992 g12 0 400 800 1200 1600 2000 temp = 35c 50s/div 1v/div 1992 g13 both inputs (inputs tied together) outputs +v s = 2.5v ?v s = ?2.5v v ocm = 0v ltc1992-10 shown for reference 1s/div 1v/div 1992 g14 both inputs (inputs tied together) outputs +v s = 2.5v ?v s = ?2.5v v ocm = 0v ltc1992-10 shown for reference 50s/div 1v/div 1992 g15 +v s = 2.5v, ?v s = ?2.5v, v ocm = 0v outputs inputs ltc1992-2 shown for reference 5s/div 1v/div 1992 g16 inputs outputs +v s = 2.5v ?v s = ?2.5v v ocm = 0v ltc1992-2 shown for reference
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage common mode rejection ratio vs frequency (note 7) power supply rejection ratio vs frequency (note 7) output balance vs frequency differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v differential phase response vs frequency applicable to the ltc1992 only. frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g17 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf r in = r fb = 10k frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g18 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf r in = r fb = 10k frequency (khz) 10 phase (deg) 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 ?160 ?180 100 1000 1992 g37 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf r in = r fb = 10k common mode voltage (v) 0 differential v os (mv) 1922 g20 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 125c ?40c 25c 85c +v s = 2.7v ?v s = 0v v ocm = 1.35v common mode voltage (v) 0 4.0 1922 g21 1.00.5 1.5 2.5 3.5 4.5 2.0 3.0 5.0 125c ?40c 85c 25c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 5v ?v s = 0v v ocm = 2.5v common mode voltage (v) ?5 3 1922 g22 ?3?4 ?2 0 2 4 ?1 1 5 125c ?40c 85c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 25c +v s = 5v ?v s = ?5v v ocm = 0v frequency (hz) 40 cmrr (db) 80 120 20 60 100 100 10k 100k 1m 1992 g23 0 1k ?v ampcm ?v ampdiff frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g24 30 20 10 0 90 100 ?v s +v s ?v s ?v ampdiff frequency (hz) 1 10 ?40 output balance (db) ?60 ?80 100 1k 10k 100k 1m 1992 g25 ?20 0 ?100 ?v outcm ?v outdiff
ltc1992 family 0 1992fa typical p er f or m ance c harac t eris t ics single-ended input large-signal step response single-ended input large-signal step response differential input small-signal step response differential input small-signal step response differential input large-signal step response differential input large-signal step response applicable to the ltc1992 only. 2s/div v outdiff (1v/div) 1992 g26 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 1.5v ?v in = 1.5v c load = 0pf gain = 1 0v 20s/div 1992 g27 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 1.5v ?v in = 1.5v gain = 1 c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v 2s/div v outdiff (1v/div) 1992 g28 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 4v ?v in = 2v c load = 0pf gain = 1 2.5v 20s/div v outdiff (1v/div) 1992 g29 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 4v ?v in = 2v gain = 1 c load = 10000pf c load = 1000pf 2.5v 1s/div v outdiff (50mv/div) 1992 g30 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 50mv ?v in = 50mv c load = 0pf gain = 1 0v 10s/div v outdiff (50mv/div) 1992 g31 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 50mv ?v in = 50mv gain = 1 c load = 10000pf c load = 1000pf 0v
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics thd + noise vs frequency thd + noise vs amplitude differential noise voltage density vs frequency v ocm gain vs frequency, v s = 2.5v single-ended input small-signal step response single-ended input small-signal step response applicable to the ltc1992 only. frequency (khz) 10 ?15 gain (db) ?5 5 100 1000 10000 1992 g19 ?25 ?20 ?10 0 ?30 ?35 c load = 10pf to 10000pf 1s/div v outdiff (50mv/div) 1992 g32 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 200mv ?v in = 100mv c load = 0pf gain = 1 2.5v 10s/div v outdiff (50mv/div) 1992 g33 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 200mv ?v in = 100mv gain = 1 c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 ?100 thd + noise (db) ?60 ?50 ?40 1k 10k 50k 1992 g34 ?70 ?80 ?90 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff input signal amplitude (v p-pdiff ) 0.1 ?100 thd + noise (db) ?90 ?80 ?70 ?60 ?40 1 10 20 1992 g35 ?50 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz frequency (hz) input referred noise (nvhz) 1000 100 10 100 1000 10000 1922 g36 10
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential gain error vs temperature v ocm gain vs frequency differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v differential phase response vs frequency applicable to the ltc1992-1 only. frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g38 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g39 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 phase (deg) 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 ?160 ?180 100 1000 1992 g40 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf temperature (c) ?50 gain error (%) 0.025 0.020 0.015 0.010 0.005 0 ?0.005 ?0.010 ?0.015 ?0.020 ?0.025 0 50 75 1992 g41 ?25 25 100 125 frequency (khz) 10 ?15 gain (db) ?5 5 100 1000 10000 1992 g42 ?25 ?20 ?10 0 ?30 ?35 c load = 10pf to 10000pf common mode voltage (v) 0 differential v os (mv) 1922 g43 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 5 4 3 2 1 0 ?1 ?2 ?3 ?4 ?5 125c ?40c 85c 25c +v s = 2.7v ?v s = 0v v ocm = 1.35v common mode voltage (v) 0 1922 g44 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125c ?40c 85c 25c differential v os (mv) 5 4 3 2 1 0 ?1 ?2 ?3 ?4 ?5 +v s = 5v ?v s = 0v v ocm = 2.5v common mode voltage (v) ?5 1922 g45 ?4 ?3 ?2 ?1 0 1 2 3 4 5 125c ?40c 85c 25c differential v os (mv) 5 4 3 2 1 0 ?1 ?2 ?3 ?4 ?5 +v s = 5v ?v s = ?5v v ocm = 0v
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics single-ended input large-signal step response single-ended input large-signal step response power supply rejection ratio vs frequency differential input small-signal step response differential input small-signal step response output balance vs frequency differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency applicable to the ltc1992-1 only. 2s/div v outdiff (1v/div) 1992 g46 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 1.5v ?v in = 1.5v c load = 0pf 0v 20s/div v outdiff (1v/div) 1992 g47 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 1.5v ?v in = 1.5v c load = 10000pf c load = 1000pf 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g48 0 1k ?v ampcm ?v ampdiff 2s/div v outdiff (1v/div) 1992 g49 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 4v ?v in = 2v c load = 0pf 2.5v 20s/div v outdiff (1v/div) 1992 g50 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 4v ?v in = 2v c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g51 30 20 10 0 90 100 ?v s +v s ?v s ?v ampdiff 1s/div v outdiff (50mv/div) 1992 g52 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 50mv ?v in = 50mv c load = 0pf 0v 10s/div v outdiff (50mv/div) 1992 g53 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 50mv ?v in = 50mv c load = 10000pf c load = 1000pf 0v frequency (hz) 1 10 ?40 output balance (db) ?60 ?80 100 1k 10k 100k 1m 1992 g54 ?20 0 ?100 ?v outcm ?v outdiff
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics single-ended input small-signal step response single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude applicable to the ltc1992-1 only. 1s/div v outdiff (50mv/div) 1992 g55 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 200mv ?v in = 100mv c load = 0pf 2.5v 10s/div v outdiff (50mv/div) 1992 g56 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 200mv ?v in = 100mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 1000 10000 1922 g57 10 input referred noise (nvhz) 1000 100 10 frequency (hz) 100 ?100 thd + noise (db) ?60 ?50 ?40 1k 10k 50k 1992 g58 ?70 ?80 ?90 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff input signal amplitude (v p-pdiff ) 0.1 ?100 thd + noise (db) ?90 ?80 ?70 ?60 ?40 1 10 20 1992 g59 ?50 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics differential gain error vs temperature v ocm gain vs frequency, v s = 2.5v differential input offset voltage vs input common mode voltage (note 7) differential input offset voltage vs input common mode voltage (note 7) differential input offset voltage vs input common mode voltage (note 7) differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v differential phase response vs frequency applicable to the ltc1992-2 only. frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g60 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 18 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g61 ?30 ?36 ?42 ?66 ?60 ?54 ?48 6 18 12 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 phase (deg) 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 ?160 ?180 100 1000 1992 g62 c load = 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf temperature (c) ?50 gain error (%) 0.05 0.04 0.03 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?0.05 0 50 75 1992 g63 ?25 25 100 125 frequency (khz) 10 ?10 gain (db) ?5 0 5 100 1000 10000 1992 g64 ?15 ?20 ?25 ?30 c load = 10pf to 10000pf common mode voltage (v) 0 differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 4.0 1992 g66 1.0 2.0 3.0 5.0 3.5 0.5 1.5 2.5 4.5 ?40c 125c 25c 85c +v s = 5v ?v s = 0v v ocm = 2.5v common mode voltage (v) 0 differential v os (mv) 0 0.5 1.0 2.4 1992 g65 ?0.5 ?1.0 ?2.0 0.6 1.2 1.8 0.3 2.7 0.9 1.5 2.1 ?1.5 1.5 2.0 +v s = 2.7v ?v s = 0v v ocm = 1.35v ?40c 25c 125c 85c common mode voltage (v) ?5 differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 3 1992 g67 ?3 ?1 1 5 2 ?4 ?2 0 4 ?40c 125c 25c +v s = 5v ?v s = ?5v v ocm = 0v 85c
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics applicable to the ltc1992-2 only. single-ended input large-signal step response single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) differential input small-signal step response differential input small-signal step response output balance vs frequency differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) 2s/div 1992 g68 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 750mv ?v in = 750mv c load = 0pf v outdiff (1v/div) 0v 20s/div 1992 g69 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 750mv ?v in = 750mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g70 0 1k ?v ampcm ?v ampdiff 2s/div 1992 g71 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 2v ?v in = 1v c load = 0pf v outdiff (1v/div) 2.5v 20s/div v outdiff (1v/div) 1992 g72 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 2v ?v in = 1v c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 1k 10k 100k 1m 1992 g73 30 20 10 0 90 100 ?v s +v s ?v s ?v ampdiff 2s/div v outdiff (50mv/div) 1992 g74 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 25mv ?v in = 25mv c load = 0pf 0v 20s/div v outdiff (50mv/div) 1992 g75 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 25mv ?v in = 25mv c load = 10000pf c load = 1000pf 0v frequency (hz) 1 10 ?40 output balance (db) ?60 ?80 100 1k 10k 100k 1m 1992 g76 ?20 0 ?100 ?v outcm ?v outdiff
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics single-ended input small-signal step response single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude applicable to the ltc1992-2 only. 2s/div v outdiff (50mv/div) 1992 g77 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 100mv ?v in = 50mv c load = 0pf 2.5v 20s/div v outdiff (50mv/div) 1992 g78 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 100mv ?v in = 50mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 1000 10000 1922 g79 10 input referred noise (nv hz) 1000 100 10 frequency (hz) 100 ?100 thd + noise (db) ?60 ?50 ?40 1k 10k 50k 1992 g80 ?70 ?80 ?90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff input signal amplitude (v p-pdiff ) 0.1 ?100 thd + noise (db) ?90 ?80 ?70 ?60 ?40 1 10 1992 g81 ?50 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics differential gain error vs temperature v ocm gain vs frequency differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v differential phase response vs frequency applicable to the ltc1992-5 only. frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g82 ?30 ?36 ?42 ?60 ?54 ?48 6 24 12 30 18 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 ?24 gain (db) ?18 ?12 ?6 0 100 1000 10000 1992 g83 ?30 ?36 ?42 ?60 ?54 ?48 6 24 12 30 18 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 phase (deg) 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 ?160 ?180 100 1000 1992 g84 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf c load = temperature (c) ?50 gain error (%) 0.050 0.025 0 ?0.025 ?0.050 ?0.075 ?0.100 ?0.125 ?01.50 0 50 75 1992 g85 ?25 25 100 125 common mode voltage (v) 0 differential v os (mv) 1922 g87 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 125c ?40c 85c 25c +v s = 2.7v ?v s = 0v v ocm = 1.35v frequency (khz) 10 ?10 gain (db) ?5 0 5 100 1000 10000 1992 g86 ?15 ?20 ?25 ?30 c load = 10pf to 10000pf common mode voltage (v) 0 1922 g88 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125c ?40c 85c 25c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 5v ?v s = 0v v ocm = 2.5v common mode voltage (v) ?5 1922 g89 ?4 ?3 ?2 ?1 0 1 2 3 4 5 125c ?40c 25c 85c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 5v ?v s = ?5v v ocm = 0v
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics applicable to the ltc1992-5 only. single-ended input large-signal step response single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) differential input small-signal step response differential input small-signal step response output balance vs frequency differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) 2s/div v outdiff (1v/div) 1992 g90 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 300mv ?v in = 300mv c load = 0pf 0v 20s/div 1992 g91 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 300mv ?v in = 300mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g92 0 1k ?v ampcm ?v ampdiff 2s/div v outdiff (1v/div) 1992 g93 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 800mv ?v in = 400mv c load = 0pf 2.5v 20s/div 1992 g94 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 800mv ?v in = 400mv c load = 10000pf c load = 1000pf v outdiff (1v/div) 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 10k 100k 1k 1m 1992 g95 30 20 10 0 90 100 +v s ?v s ?v s ?v ampdiff 5s/div v outdiff (50mv/div) 1992 g96 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 10mv ?v in = 10mv c load = 0pf 0v 50s/div v outdiff (50mv/div) 1992 g97 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 10mv ?v in = 10mv c load = 10000pf c load = 1000pf 0v frequency (hz) 1 10 ?40 output balance (db) ?60 ?80 100 1k 10k 100k 1m 1992 g98 ?20 0 ?100 ?v outcm ?v outdiff
ltc1992 family 0 1992fa typical p er f or m ance c harac t eris t ics single-ended input small-signal step response single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude 5s/div v outdiff (50mv/div) 1992 g99 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 40mv ?v in = 20mv c load = 0pf 2.5v 50s/div 1992 g100 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 40mv ?v in = 20mv c load = 10000pf c load = 1000pf v outdiff (50mv/div) 2.5v frequency (hz) 100 1000 10000 1922 g101 10 input referred noise (nv hz) 1000 100 10 frequency (hz) 100 ?100 thd + noise (db) ?60 ?50 ?40 1k 10k 50k 1992 g102 ?70 ?80 ?90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 10v p-pdiff v out = 5v p-pdiff 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v input signal amplitude (v p-pdiff ) 0.1 ?100 thd + noise (db) ?90 ?80 ?70 ?60 ?40 1 5 1992 g103 ?50 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v 50khz 20khz 10khz 5khz 2khz 1khz applicable to the ltc1992-5 only.
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics applicable to the ltc1992-10 only. differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential input offset voltage vs input common mode voltage differential gain error vs temperature v ocm gain vs frequency differential input differential gain vs frequency, v s = 2.5v single-ended input differential gain vs frequency, v s = 2.5v differential phase response vs frequency frequency (khz) 10 ?30 gain (db) ?20 ?10 0 10 100 1000 10000 1992 g104 ?40 ?50 ?60 20 30 40 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 ?30 gain (db) ?20 ?10 0 10 100 1000 10000 1992 g105 ?40 ?50 ?60 20 30 40 c load = 10000pf c load = 5000pf c load = 1000pf c load = 500pf c load = 100pf c load = 50pf c load = 10pf frequency (khz) 10 phase (deg) 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 ?160 ?180 100 1000 1992 g106 10pf 50pf 100pf 500pf 1000pf 5000pf 10000pf c load = temperature (c) ?50 gain error (%) 0.050 0.025 0 ?0.025 ?0.050 ?0.075 ?0.100 ?0.125 ?0.150 ?0.175 ?0.200 0 50 75 1992 g107 ?25 25 100 125 frequency (khz) 10 ?10 gain (db) ?5 0 5 100 1000 10000 1992 g108 ?15 ?20 ?25 ?30 c load = 10pf to 10000pf common mode voltage (v) 0 1922 g109 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 125c ?40c 85c 25c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 2.7v ?v s = 0v v ocm = 1.35v common mode voltage (v) 0 1922 g110 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 125c ?40c 85c 25c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 5v ?v s = 0v v ocm = 2.5v common mode voltage (v) ?5 1922 g111 ?4 ?3 ?2 ?1 0 1 2 3 4 5 125c ?40c 85c 25c differential v os (mv) 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 +v s = 5v ?v s = ?5v v ocm = 0v
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics applicable to the ltc1992-10 only. single-ended input large-signal step response single-ended input large-signal step response power supply rejection ratio vs frequency (note 7) differential input small-signal step response differential input small-signal step response output balance vs frequency differential input large-signal step response differential input large-signal step response common mode rejection ratio vs frequency (note 7) 2s/div 1992 g112 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 150mv ?v in = 150mv c load = 0pf v outdiff (1v/div) 0v 20s/div v outdiff (1v/div) 1992 g113 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 150mv ?v in = 150mv c load = 10000pf c load = 1000pf 0v frequency (hz) 30 cmrr (db) 90 100 20 10 80 50 70 60 40 100 10k 100k 1m 1992 g114 0 1k ?v ampcm ?v ampdiff 2s/div 1992 g115 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 400mv ?v in = 200mv c load = 0pf v outdiff (1v/div) 2.5v 20s/div v outdiff (1v/div) 1992 g116 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 400mv ?v in = 200mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 10 40 psrr (db) 50 60 70 80 100 10k 100k 1k 1m 1992 g117 30 20 10 0 90 100 +v s ?v s ?v s ?v ampdiff 10s/div 1992 g118 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 5mv ?v in = 5mv c load = 0pf v outdiff (50mv/div) 0v 100s/div v outdiff (50mv/div) 1992 g119 +v s = 2.5v ?v s = ?2.5v v ocm = 0v +v in = 5mv ?v in = 5mv c load = 10000pf c load = 1000pf 0v frequency (hz) 1 10 ?60 output balance (db) 100 1k 10k 100k 1m 1992 g120 ?40 ?20 0 ?80 ?100 ?120 ?v outcm ?v outdiff
ltc1992 family 1992fa typical p er f or m ance c harac t eris t ics applicable to the ltc1992-10 only. single-ended input small-signal step response single-ended input small-signal step response differential noise voltage density vs frequency thd + noise vs frequency thd + noise vs amplitude 10s/div 1992 g121 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 20mv ?v in = 10mv c load = 0pf v outdiff (50mv/div) 2.5v 100s/div v outdiff (50mv/div) 1992 g122 +v s = 5v ?v s = 0v v ocm = 2.5v +v in = 0v to 20mv ?v in = 10mv c load = 10000pf c load = 1000pf 2.5v frequency (hz) 100 1000 10000 1922 g123 10 input referred noise (nv hz) 1000 100 10 frequency (hz) 100 ?100 thd + noise (db) ?60 ?50 ?40 1k 10k 50k 1992 g124 ?70 ?80 ?90 v out = 1v p-pdiff v out = 2v p-pdiff v out = 5v p-pdiff 500khz measurement bandwidth +v s = 5v ?v s = ?5v v ocm = 0v input signal amplitude (v p-pdiff ) 0.1 ?100 thd + noise (db) ?90 ?80 ?70 ?60 ?40 1 2 1992 g125 ?50 50khz 20khz 10khz 5khz 2khz 1khz
ltc1992 family 1992fa p in func t ions Cin, +in (pins 1, 8): inverting and noninverting inputs of the amplifier. for the ltc1992 part, these pins are connected directly to the amplifiers p-channel mosfet input devices. the fixed gain ltc1992-x parts have preci- sion, on-chip gain setting resistors. the input resistors are nominally 30k for the ltc1992-1, ltc1992-2 and ltc1992-5 parts. the input resistors are nominally 15k for the ltc1992-10 part. v ocm (pin 2): output common mode voltage set pin. the voltage on this pin sets the output signals common mode voltage level. the output common mode level is set independent of the input common mode level. this is a high impedance input and must be connected to a known and controlled voltage. it must never be left floating. +v s , Cv s (pins 3, 6): the +v s and Cv s power supply pins should be bypassed with 0.1f capacitors to an adequate ana- log ground or ground plane. the bypass capacitors should be located as closely as possible to the supply pins. +out, Cout (pins 4, 5): the positive and negative outputs of the amplifier. these rail-to-rail outputs are designed to drive capacitive loads as high as 10,000pf. v mid (pin 7): mid-supply reference. this pin is connected to an on-chip resistive voltage divider to provide a mid- supply reference. this provides a convenient way to set the output common mode level at half-supply. if used for this purpose, pin 2 will be shorted to pin 7, pin 7 should be bypassed with a 0.1f capacitor to ground. if this refer- ence voltage is not used, leave the pin floating. b lock diagra m s (1992) + ? 1 7 2 6 3 8 5 4 + ? 200k 200k +v s ?v s v + v ? 30k 30k a1 + + + ? a2 +out 1992 bd ?in v mid v ocm +in ?out +v s ?v s +v s ?v s
ltc1992 family 1992fa b lock diagra m s (1992-x) ? ? + + +v s +v s ?in v mid +in ?v s +v s ?v s ?v s +out ?out v ocm 200k 200k r in r fb r in r fb 4 5 2 6 1 3 7 8 1992-x bd part ltc1992-1 ltc1992-2 ltc1992-5 ltc1992-10 r in 30k 30k 30k 15k r fb 30k 60k 150k 150k a pplica t ions i n f or m a t ion theory of operation the ltc1992 family consists of five fully differential, low power amplifiers. the ltc1992 is an unconstrained fully differential amplifier. the ltc1992-1, ltc1992-2, ltc1992- 5 and ltc1992-10 are fixed gain blocks (with gains of 1, 2, 5 and 10 respectively) featuring precision on-chip resistors for accurate and ultra stable gain. in many ways, a fully differential amplifier functions much like the familiar, ubiquitous op amp. however, there are s e veral key areas where the two differ. referring to figure 1, an op amp has a differential input, a high open-loop gain and utilizes negative feedback (through resistors) to set the closed-loop gain and thus control the amplifiers gain with great precision. a fully differential amplifier has all of these features plus an additional input and a complemen- tary output. the complementary output reacts to the input signal in the same manner as the other output, but in the opposite direction. two outputs changing in an equal but opposite manner require a common reference point (i.e., opposite relative to what?). the additional input, the v ocm pin, sets this reference point. the voltage on the v ocm input directly sets the output signals common mode voltage and allows the output signals common mode voltage to be set completely independent of the input signals common mode voltage. uncoupling the input and output common mode voltages makes signal level shifting easy. for a better understanding of the operation of a fully dif- ferential amplifier, refer to figure 2. here, the ltc1992 functional block diagram adds external resistors to real- ize a basic gain block. note that the ltc1992 functional block diagram is not an exact replica of the ltc1992 circuitry. however, the block diagram is correct and is a very good tool for understanding the operation of fully differential amplifier circuits. basic op amp fundamentals together with this block diagram provide all of the tools needed for understanding fully differential amplifier circuit applications. the ltc1992 block diagram has two op amps, two sum- ming blocks (pay close attention the signs ) and four resis- tors. two resistors, r mid1 and r mid2 , connect directly to the v mid pin and simply provide a convenient mid-supply reference. its use is optional and it is not involved in the operation of the ltc1992s amplifier. the ltc1992 functions through the use of two servo networks each employing
ltc1992 family 1992fa a pplica t ions i n f or m a t ion figure 1. comparison of an op amp and a fully differential amplifier figure 2. ltc1992 functional block diagram with external gain setting resistors ? ? + + ? ? + + 1992 f01 r in r in r fb r fb fully differential ampli?er with negative feedback fully differential ampli?er ?v in +v in v ocm v ocm v ocm ?v out +v out ? + r in r fb op amp with negative feedback v in v out r fb r in gain = ? r fb r in gain = ? +out ? differential input ? high open-loop gain ? differential output ? v ocm input sets output common mode level ?out ?in +in v ocm ? + op amp out ltc1992 a o ltc1992 a o ltc1992 ltc1992 ? differential input ? high open-loop gain ? single-ended output ?in +in + ? 7 2 6 3 + ? r mid1 200k r mid2 200k inp inm v + v ? r cmp 30k r cmm 30k a1 s p ltc1992 s m + + + ? a2 +out 1992 f02 ?in +v in ?v in r in r fb r in v mid v ocm +in ?out ?v out +v out +v s ?v s 5 4 r fb 1 8
ltc1992 family 1992fa a pplica t ions i n f or m a t ion negative feedback and using an op amps differential input to create the servos summing junction. one servo controls the signal gain path. the differential input of op amp a1 creates the summing junction of this servo. any voltage present at the input of a1 is amplified (by the op amps large open-loop gain), sent to the summing blocks and then onto the outputs. taking note of the signs on the summing blocks, op amp a1s output moves +out and Cout in opposite directions. applying a voltage step at the inm node increases the +out voltage while the Cout voltage decreases. the rfb resistors connect the outputs to the appropriate inputs establishing negative feedback and closing the servos loop. any servo loop always attempts to drive its error voltage to zero. in this servo, the error voltage is the voltage between the inm and inp nodes, thus a1 will force the voltages on the inp and inm nodes to be equal (within the parts dc offset, open loop gain and bandwidth limits). the virtual short between the two inputs is conceptually the same as that for op amps and is critical to understanding fully differential amplifier applications. the other servo controls the output common mode level. the differential input of op amp a2 creates the summing junction of this servo. similar to the signal gain servo above, any voltage present at the input of a2 is amplified, sent to the summing blocks and then onto the outputs. however, in this case, both outputs move in the same direc- tion. the resistors r cmp and r cmm connect the +out and Cout outputs to a2s inverting input establishing negative feedback and closing the servos loop. the midpoint of resistors r cmp and r cmm derives the outputs common mode level (i.e., its average). this measure of the outputs common mode level connects to a2s inverting input while a2s noninverting input connects directly to the v ocm pin. a2 forces the voltages on its inverting and noninverting inputs to be equal. in other words, it forces the output common mode voltage to be equal to the voltage on the v ocm input pin. for any fully differential amplifier application to function properly both the signal gain servo and the common mode level servo must be satisfied. when analyzing an applica- tions circuit, the inp node voltage must equal the inm node voltage and the output common mode voltage must equal the v ocm voltage. if either of these servos is taken out of the specified areas of operation (e.g., inputs taken beyond the common mode range specifications, outputs hitting the supply rails or input signals varying faster than the part can track), the circuit will not function properly. fully differential amplifier signal conventions fully differential amplifiers have a multitude of signals and signal ranges to consider. to maintain proper operation with conventional op amps, the op amps inputs and its output must not hit the supply rails and the input signals common mode level must also be within the parts speci- fied limits. these considerations also apply to fully dif- ferential amplifiers, but here there is an additional output to consider and common mode level shifting complicates matters. figure 3 provides a list of the many signals and specifications as well as the naming convention. the phrase common mode appears in many places and often leads to confusion. the fully differential amplifiers ability to uncouple input and output common mode levels yields great design flexibility, but also complicates matters some. for simplicity, the equations in figure 3 also assume an ideal amplifier and perfect resistor matching. for a detailed analysis, consult the fully differential amplifier applications circuit analysis section. basic applications circuits most fully differential amplifier applications circuits employ symmetrical feedback networks and are familiar territory for op amp users. symmetrical feedback networks require that the Cv in /+v out network is a mirror image duplicate of the +v in /Cv out network. each of these half circuits is basi- cally just a standard inverting gain op amp circuit. figure 4 shows three basic inverting gain op amp circuits and their corresponding fully differential amplifier cousins. the vast majority of fully differential amplifier circuits derive from old tried and true inverting op amp circuits. to create a fully differential amplifier circuit from an inverting op amp circuit, first simply transfer the op amps v in /v out network to the fully differential amplifiers Cv in /+v out nodes. then, take a mirror image duplicate of the network and apply it to the fully differential amplifiers +v in /Cv out nodes. op amp users can comfortably transfer any inverting op amp circuit to a fully differential amplifier in this manner.
ltc1992 family 1992fa single-ended to differential conversion one of the most important applications of fully differential amplifiers is single-ended signaling to differential signaling conversion. many systems have a single-ended signal that must connect to an adc with a differential input. the adc could be run in a single-ended manner, but performance usually degrades. fortunately, all of basic applications circuits shown in figure 4, as well as all of the fixed gain ltc1992-x parts, are equally suitable for both differential and single-ended input signals. for single-ended input signals, connect one of the inputs to a reference voltage (e.g., ground or mid-supply) and connect the other to the signal path. there are no tradeoffs here as the parts performance is the same with single-ended or differential input signals. which input is used for the signal path only affects the polarity of the differential output signal. signal level shifting another important application of fully differential ampli- fier is signal level shifting. single-ended to differential conversion accompanied by a signal level shift is very commonplace when driving adcs. as noted in the theory of operation section, fully differential amplifiers have a com- mon mode level servo that determines the output common mode level independent of the input common mode level. to set the output common mode level, simply apply the desired voltage to the v ocm input pin. the voltage range on the v ocm pin is from (Cv s + 0.5v) to (+v s C 1.3v). figure 3. fully differential amplifier signal conventions (ideal amplifier and perfect resistor matching is assumed) ? ? + + 1992 f03 r in r in r fb v ocm v ocm r fb b b ?b ?b ?v in ?a ?a v incm v outcm v indiff 4av p-pdiff a a +v in 2av p-p 2av p-p = v indiff = +v in ? ?v in 2bv p-p 2bv p-p differential input voltage = v incm = input common mode voltage +v out = ? ? + v ocm ; v oscm = 0v +v in ? ?v in +v in + ?v in 2 = v outdiff = +v out ? ?v out differential output voltage ?v out +v out ltc1992 v outdiff 4bv p-pdiff 1 2 r fb r in = v outcm = output common mode voltage +v out + ?v out 2 ( ) ?v out = ? ? + v ocm ; v oscm = 0v ?v in ? +v in 1 2 r fb r in v outdiff = v indiff ? r fb r in r n (0.13nv/ hz) v ampcm = v inp + v inm 2 cmrr = ; +v in = ?v in ?v ampcm ?v ampdiff output balance = ?v outcm ?v outdiff e nout = where: e nout = output referred noise voltage density e nin = input referred noise voltage density (resistive noise is already included in the specifications for the fixed gain ltc1992-x parts) + 1 r fb r in v outcm = v ocm v ampdiff = v inp ? v inm v oscm = v outcm ? v ocm ( ) ( ) v osdiffout = v osdiffin ? + 1 r fb r in ( ) inm inp r in ? r fb r in + r fb ( ) ? e nin 2 + r n 2 a pplica t ions i n f or m a t ion
ltc1992 family 1992fa a pplica t ions i n f or m a t ion figure 4. basic fully differential amplifier application circuits (note: single-ended to differential conversion is easily accomplished by connecting one of the input nodes, +v in or Cv in , to a dc reference level (e.g., ground)) ? ? + + r in r in r fb r fb gain block ?v in +v in v ocm ?v out +v out ? + r in v in r fb v out r fb r in gain = ltc1992 ? ? + + r in r in r fb r fb ac coupled gain block ?v in +v in v ocm ?v out +v out ? + r in c in c in c in v in r fb v out ltc1992 ? ? + + r in r in r fb r fb single pole lowpass filter ?v in +v in r fb r in w p s + w p ; w p = v ocm ?v out +v out ? + r in v in r fb c v out h (s) = h o ? where h o = ltc1992 c c 1 r fb ? c ? ? + + r1 r3 r3 r4 r4 r1 r2 r2 3-pole lowpass filter ?v in +v in r2 r1 ; w p = ; w o = v ocm ?v out 1992 f04 +v out ? + r1 r3 r4 r2 c1 c2 v out where h o = ltc1992 c3 c1 c1 1 r4c3 1 r2r3c1c2 c2 2 c3 2 w p s + w p h (s) = h o ( ) w o 2 s 2 + s + w o q w o 2 ( ) v in r fb r in ; w p = h o = 1 r in ? c in s s + w p h (s) = h o ? c2 c1 r1 ? r2r3 r1 r2 + r1 r2 + r2 r3 ? q =
ltc1992 family 0 1992fa a pplica t ions i n f or m a t ion the v ocm input pin has a very high input impedance and is easily driven by even the weakest of sources. many adcs provide a voltage reference output that defines either its common mode level or its full-scale level. apply the adcs reference potential either directly to the v ocm pin or through a resistive voltage divider depending on the reference voltages definition. when controlling the v ocm pin by a high impedance source, connect a bypass capacitor (1000pf to 0.1f) from the v ocm pin to ground to lower the high frequency impedance and limit external noise coupling. other applications will want the output biased at a midpoint of the power supplies for maximum output voltage swing. for these applications, the ltc1992 provides a mid-supply potential at the v mid pin. the v mid pin connects to a simple resistive voltage divider with two 200k resistors connected between the supply pins. to use this feature, connect the v mid pin to the v ocm pin and bypass this node with a capacitor. one undesired effect of utilizing the level shifting function is an increase in the differential output offset voltage due to gain setting resistor mismatch. the offset is approximately the amount of level shift (v outcm C v incm ) multiplied by the amount of resistor mismatch. for example, a 2v level shift with 0.1% resistors will give around 2mv of output offset (2 ? 0.1% = 2mv). the exact amount of offset is dependent on the applications gain and the resistor mismatch. for a detail description, consult the fully differential amplifier applications circuit analysis section. cmrr and output balance one common misconception of fully differential amplifiers is that the common mode level servo guarantees an infinite common mode rejection ratio (cmrr). this is not true. the common mode level servo does, however, force the two outputs to be truly complementary (i.e., exactly opposite or 180 degrees out of phase). output balance is a measure of how complementary the two outputs are. at low frequencies, cmrr is primarily determined by the matching of the gain setting resistors. like any op amp, the ltc1992 does not have infinite cmrr, however resistor mismatching of only 0.018%, halves the circuits cmrr. standard 1% tolerance resistors yield a cmrr of about 40db. for most applications, resistor matching dominates low frequency cmrr performance. the specifications for the fixed gain ltc1992-x parts include the on-chip resistor matching effects. also, note that an input common mode signal appears as a differential output signal reduced by the cmrr. as with op amps, at higher frequencies the cmrr degrades. refer to the typical performance plots for the details of the cmrr performance over frequency. at low frequencies, the output balance specification is determined by the matching of the on-chip r cmm and r cmp resistors. at higher frequencies, the output bal- ance degrades. refer to the typical performance plots for the details of the output balance performance over frequency. input impedance the input impedance for a fully differential amplifier ap- plication circuit is similar to that of a standard op amp inverting amplifier. one major difference is that the input impedance is different for differential input signals and single-ended signals. referring to figure 3, for differential input signals the input impedance is expressed by the following expression: r indiff = 2 ? r in for single-ended signals, the input impedance is expressed by the following expression: r r r r r ins in fb in fb -e = + ( ) 1 2 ? ? the input impedance for single-ended signals is slightly higher than the r in value since some of the input signal is fed back and appears as the amplifiers input common mode level. this small amount of positive feedback in- creases the input impedance. driving capacitive loads the ltc1992 family of parts is stable for all capacitive loads up to at least 10,000pf. while stability is guaranteed, the parts performance is not unaffected by capacitive load- ing. large capacitive loads increase output step response ringing and settling time, decrease the bandwidth and increase the frequency response peaking. refer to the
ltc1992 family 1992fa a pplica t ions i n f or m a t ion typical performance plots for small-signal step response, large-signal step response and gain over frequency to appraise the effects of capacitive loading. while the con- sequences are minor in most instances, consider these effects when designing application circuits with large capacitive loads. input signal amplitude considerations for application circuits to operate correctly, the amplifier must be in its linear operating range. to be in the linear operating range, the input signals common mode voltage must be within the parts specified limits and the rail-to-rail outputs must stay within the supply voltage rails. addition- ally, the fixed gain ltc1992-x parts have input protection diodes that limit the input signal to be within the supply voltage rails. the unconstrained ltc1992 uses external resistors allowing the source signals to go beyond the supply voltage rails. when taken outside of the linear operating range, the circuit does not perform as expected, however nothing extreme occurs. outputs driven into the supply voltage rails are simply clipped. there is no phase reversal or oscillation. once the outputs return to the linear operating range, there is a small recovery time, then normal opera- tion proceeds. when the input common mode voltage is below the specified lower limit, on-chip protection diodes conduct and clamp the signal. once the signal returns to the specified operating range, normal operation proceeds. if the input common mode voltage goes slightly above the specified upper limit (by no more than about 500mv), the amplifiers open-loop gain reduces and dc offset and closed-loop gain errors increase. return the input back to the specified range and normal performance commences. if taken well above the upper limit, the amplifiers input stage is cut off. the gain servo is now open loop; however, the common mode servo is still functional. output bal- ance is maintained and the outputs go to opposite supply rails. however, which output goes to which supply rail is random. once the input returns to the specified input common mode range, there is a small recovery time then normal operation proceeds. the ltc1992s input signal common mode range (v incmr ) is from (Cv s C 0.1v) to (+v s C 1.3v). this specification applies to the voltage at the amplifiers input, the inp and inm nodes of figure 2. the specifications for the fixed gain ltc1992-x parts reflect a higher maximum limit as this specification is for the entire gain block and references the signal at the input resistors. differential input signals and single-ended signals require a slightly different set of formulae. differential signals separate very nicely into common mode and differential components while single ended signals do not. refer to figure 5 for the formulae for calculating the available signal range. additionally, table 1 lists some common configurations and their ap- propriate signal levels. the ltc1992s outputs allow rail-to-rail signal swings. the output voltage on either output is a function of the input signals amplitude, the gain configured and the output signals common mode level set by the v ocm pin. for maximum signal swing, the v ocm pin is set at the midpoint of the supply voltages. for other applications, such as an adc driver, the required level must fall within the v ocm range of (Cv s + 0.5v) to (+v s C 1.3v). for single-ended input signals, it is not always obvious which output will clip first thus both outputs are calculated and the minimum value determines the signal limit. refer to figure 5 for the formula and table 1 for examples. to ensure proper linear operation both the input common mode level and the output signal level must be within the specified limits. these same criteria are also present with standard op amps. however, with a fully differential amplifier, it is a bit more complex and old familiar op amp intuition often leads to the wrong result. this is especially true for single-ended to differential conversion with level shifting. the required calculations are a bit tedious, but are necessary to guarantee proper linear operation.
ltc1992 family 1992fa a pplica t ions i n f or m a t ion figure 5. input signal limitations ? ? + + r in inm node inp node r in r fb v ocm v ocm a. calculate v incm minimum and maximum given r in , r fb and v ocm v incm(max) = (+v s ? 1.3v) + (+v s ? 1.3v ? v ocm ) v incm(min) = (?v s ? 0.1v) + (?v s ? 0.1v ? v ocm ) b. with a known v incm , r in , r fb and v ocm , calculate common mode voltage at inp and inm nodes (v incm(amp) ) and check that it is within the specified limits. v incm(amp) = = v incm + v ocm r fb b b ?b ?b ?v in ?a ?a v incm v outcm v indiff 4av p-pdiff a a +v in 2av p-p 2av p-p 2bv p-p 2bv p-p ?v out +v out ltc1992 v outdiff 4bv p-pdiff 1 g 1 g 4 g 4 g v inp + v inm 2 g g + 1 1 g + 1 differential input signals ? ? + + 1992 f05 r in inm node inp node r in r fb v ocm v ocm r fb b b ?b ?b v inref ?a v outcm v ref a v insig 2av p-p 2bv p-p 2bv p-p ?v out +v out ltc1992 v outdiff 4bv p-pdiff single end input signals input common mode limits output signal clipping limit input common mode limits (note: for the fixed gain ltc1992-x parts, v inref and v insig cannot exceed the supplies) output signal clipping limit or or v indiff(max) (v p-pdiff ) = the lesser value of (+v s ? v ocm ) or (v ocm ? ?v s ) v inref 2 1 g v insig(max) = 2 v insig(max) = the lesser value of v inref + (+v s ? v ocm ) or v inref + (v ocm ? ?v s ) +v s ? 1.3v ? +v s ? 1.3v ? v ocm + ( () ) v inref 2 1 g v insig(min) = 2 ?v s ? 0.1v ? ?v s ? 0.1v ? v ocm + ( () ) 1 g 2 g 2 g v insig(min) = the greater value of v inref + (?v s ? v ocm ) or v inref + (v ocm ? +v s ) 2 g 2 g v insigp-p = 2 (+v s ? ?v s ) ? 1.2v (+v s ? ?v s ) ? 1.2v + ( () ) r fb r in g = r fb r in g =
ltc1992 family 1992fa a pplica t ions i n f or m a t ion table 1. input signal limitations for some common applications differential input signal, v ocm at typical adc levels. (v incm must be within the min and max table values and v indiff must be less than the table value) +v s (v) Cv s (v) gain (v/v) v ocm (v) v incm(max) (v) v incm(min) (v) v indiff(max) (v p-pdiff ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1 1.800 C1.200 4.00 4.00 2.7 0 2 1 1.600 C0.650 2.00 4.00 2.7 0 5 1 1.480 C0.320 0.80 4.00 2.7 0 10 1 1.440 C0.210 0.40 4.00 5 0 1 2 5.400 C2.200 8.00 8.00 5 0 2 2 4.550 C1.150 4.00 8.00 5 0 5 2 4.040 C0.520 1.60 8.00 5 0 10 2 3.870 C0.310 0.80 8.00 5 C5 1 2 5.400 C12.200 12.00 12.00 5 C5 2 2 4.550 C8.650 6.00 12.00 5 C5 5 2 4.040 C6.520 2.40 12.00 5 C5 10 2 3.870 C5.810 1.20 12.00 differential input signal, v ocm at mid-supply. (v incm must be within the min and max table values and v indiff must be less than the table value) +v s (v) Cv s (v) gain (v/v) v ocm (v) v incm(max) (v) v incm(min) (v) v indiff(max) (v p-pdiff ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1.35 1.450 C1.550 5.40 5.40 2.7 0 2 1.35 1.425 C0.825 2.70 5.40 2.7 0 5 1.35 1.410 C0.390 1.08 5.40 2.7 0 10 1.35 1.405 C0.245 0.54 5.40 5 0 1 2.5 4.900 C2.700 10.00 10.00 5 0 2 2.5 4.300 C1.400 5.00 10.00 5 0 5 2.5 3.940 C0.620 2.00 10.00 5 0 10 2.5 3.820 C0.360 1.00 10.00 5 C5 1 0 7.400 C10.200 20.00 20.00 5 C5 2 0 5.550 C7.650 10.00 20.00 5 C5 5 0 4.440 C6.120 4.00 20.00 5 C5 10 0 4.070 C5.610 2.00 20.00
ltc1992 family 1992fa a pplica t ions i n f or m a t ion table 1. input signal limitations for some common applications +v s (v) Cv s (v) gain (v/v) v ocm (v) v inref (v) v insig(max) (v) v insig(min) (v) v insigp-p(max) (v p-p around v inref ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1.35 1.35 1.550 C1.350 0.40 0.40 2.7 0 2 1.35 1.35 1.500 0.000 0.30 0.60 2.7 0 5 1.35 1.35 1.470 0.810 0.24 1.20 2.7 0 10 1.35 1.35 1.460 1.080 0.22 2.20 5 0 1 2.5 2.5 7.300 C2.500 9.60 9.60 5 0 2 2.5 2.5 5.000 0.000 5.00 10.00 5 0 5 2.5 2.5 3.500 1.500 2.00 10.00 5 0 10 2.5 2.5 3.000 2.000 1.00 10.00 5 C5 1 0 0 10.000 C10.000 20.00 20.00 5 C5 2 0 0 5.000 C5.000 10.00 20.00 5 C5 5 0 0 2.000 C2.000 4.00 20.00 5 C5 10 0 0 1.000 C1.000 2.00 20.00 mid-supply referenced single-ended input signal, v ocm at mid-supply. (the v insig min and max values listed account for both the input common mode limits and the output clipping) +v s (v) Cv s (v) gain (v/v) v ocm (v) v inref (v) v insig(max) (v) v insig(min) (v) v insigp-p(max) (v p-p around v inref ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1 1.35 2.250 C0.650 1.80 1.80 2.7 0 2 1 1.35 1.850 0.350 1.00 2.00 2.7 0 5 1 1.35 1.610 0.950 0.52 2.60 2.7 0 10 1 1.35 1.530 1.150 0.36 3.60 5 0 1 2 2.5 6.500 C1.500 8.00 8.00 5 0 2 2 2.5 4.500 0.500 4.00 8.00 5 0 5 2 2.5 3.300 1.700 1.60 8.00 5 0 10 2 2.5 2.900 2.100 0.80 8.00 5 C5 1 2 0 6.000 C6.000 12.00 12.00 5 C5 2 2 0 3.000 C3.000 6.00 12.00 5 C5 5 2 0 1.200 C1.200 2.40 12.00 5 C5 10 2 0 0.600 C0.600 1.20 12.00 mid-supply referenced single-ended input signal, v ocm at typical adc levels. (the v insig min and max values listed account for both the input common mode limits and the output clipping)
ltc1992 family 1992fa a pplica t ions i n f or m a t ion fully differential amplifier applications circuit analysis all of the previous applications circuit discussions have as- sumed perfectly matched symmetrical feedback networks. to consider the effects of mismatched or asymmetrical feedback networks, the equations get a bit messier. figure 6 lists the basic gain equation for the differential output voltage in terms of +v in , Cv in , v osdiff , v outcm and the feedback factors 1 and 2. the feedback factors are simply the portion of the output that is fed back to the input summing junction by the r fb -r in resistive voltage divider. 1 and 2 have the range of zero to one. the v outcm term also includes its offset voltage, v oscm , and its gain mismatch term, k cm . the k cm term is determined by the matching of the on-chip r cmp and r cmm resistors in the common mode level servo (see figure 2). while mathematically correct, the basic signal equation does not immediately yield any intuitive feel for fully differential amplifier application operation. however, by nulling out specific terms, some basic observations and sensitivities come forth. setting 1 equal to 2, v osdiff to zero and v outcm to v ocm gives the old gain equation from figure 3. the ground referenced, single-ended input signal equation yields the interesting result that the driven side feedback factor ( 1) has a very different sensitivity than the grounded side ( 2). the cmrr is twice the feedback factor difference divided by the feedback fac- tor sum. the differential output offset voltage has two terms. the first term is determined by the input offset term, v osdiff , and the applications gain. note that this term equates to the formula in figure 3 when 1 equals 2. the amount of signal level shifting and the feedback factor mismatch determines the second term. this term table 1. input signal limitations for some common applications single supply ground referenced single-ended input signal, v ocm at mid-supply. (the v insig min and max values listed account for both the input common mode limits and the output clipping) single supply ground referenced single-ended input signal, v ocm at typical adc reference levels. (the v insig min and max values listed account for both the input common mode limits and the output clipping) +v s (v) Cv s (v) gain (v/v) v ocm (v) v inref (v) v insig(max) (v) v insig(min) (v) v insigp-p(max) (v p-p around v inref ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1.35 0 2.700 C2.700 5.40 5.40 2.7 0 2 1.35 0 1.350 C1.350 2.70 5.40 2.7 0 5 1.35 0 0.540 C0.540 1.08 5.40 2.7 0 10 1.35 0 0.270 C0.270 0.54 5.40 5 0 1 2.5 0 5.000 C5.000 10.00 10.00 5 0 2 2.5 0 2.500 C2.500 5.00 10.00 5 0 5 2.5 0 1.000 C1.000 2.00 10.00 5 0 10 2.5 0 0.500 C0.500 1.00 10.00 +v s (v) Cv s (v) gain (v/v) v ocm (v) v inref (v) v insig(max) (v) v insig(min) (v) v insigp-p(max) (v p-p around v inref ) v outdiff(max) (v p-pdiff ) 2.7 0 1 1 0 2.000 C2.000 4.00 4.00 2.7 0 2 1 0 1.000 C1.000 2.00 4.00 2.7 0 5 1 0 0.400 C0.400 0.80 4.00 2.7 0 10 1 0 0.200 C0.200 0.40 4.00 5 0 1 2 0 4.000 C4.000 8.00 8.00 5 0 2 2 0 2.000 C2.000 4.00 8.00 5 0 5 2 0 0.800 C0.800 1.60 8.00 5 0 10 2 0 0.400 C0.400 0.80 8.00
ltc1992 family 1992fa a pplica t ions i n f or m a t ion quantifies the undesired effect of signal level shifting discussed earlier in the signal level shifting section. asymmetrical feedback application circuits the basic signal equation in figure 6 also gives insight to another piece of intuition. the feedback factors may be deliberately set to different values. one interesting class of these application circuits sets one or both of the feedback factors to the extreme values of either zero or one. figure 7 shows three such circuits. at first these application circuits may look to be unstable or open loop. it is the common mode feedback loop that enables these circuits to function. while they are useful circuits, they have some shortcomings that must be con- sidered. first, do to the severe feedback factor asymmetry, the v ocm level influences the differential output voltage with about the same strength as the input signal. with this much gain in the v ocm path, differential output offset and noise increase. the large v ocm to v outdiff gain also necessitates that these circuits are largely limited to dual, split supply voltage applications with a ground referenced input signal and a grounded v ocm pin. the top application circuit in figure 7 yields a high input impedance, precision gain of 2 block without any external resistors. the on-chip common mode feedback servo resistors determine the gain precision (better than 0.1 percent). by using the Cv out output alone, this circuit is also useful to get a precision, single-ended output, high input impedance inverter. to intuitively understand this circuit, consider it as a standard op amp voltage follower (delivered through the signal gain servo) with a comple- mentary output (delivered through the common mode level servo). as usual, the amplifiers input common mode range must not be exceeded. as with a standard op amp voltage follower, the common mode signal seen at the amplifiers input is the input signal itself. this condition limits the input signal swing, as well as the output signal swing, to be the input signal common mode range specification. the middle circuit is largely the same as the first except that the noninverting amplifier path has gain. note that figure 6. basic equations for mismatched or asymmetrical feedback applications circuits ? ? + + r in2 r in1 2[+v in ? (1 ? b1) ? (?v in ) ? (1 ? b2)] + 2v osdiff + 2v outcm (b1 ? b2) b1 + b2 r fb1 v ocm v ocm v outdiff = where: ? for ground referenced, single-ended input signal, let +v in = v insig and ?v in = 0v r fb2 ?v in v indiff +v in ? ?v in +v in ?v out +v out 1992 f06 ltc1992 v outdiff +v out ? ?v out 2 ? v insig ? (1 ? b1) + 2v osdiff + 2v outcm (b1 ? b2) b1 + b2 v outdiff = ? common mode rejection: set +v in = ?v in = v incm , v osdiff = 0v, v outcm = 0v ?v incm ?v outdiff cmrr = = 2 ; output referred b1 + b2 b2 ? b1 b2 ? b1 b1 + b2 ? output dc offset voltage: set +v in = ?v in = v incm v osdiffout = v osdiff + (v outcm ? v incm ) 2 2 b1 + b2 r in1 r in1 + r fb1 b 1 = ;b2 = ; v osdiff = amplifier input referred offset voltage v outcm = k cm ? v ocm + v oscm 0.999 < k cm < 1.001 r in2 r in2 + r fb2
ltc1992 family 1992fa figure 7. asymmetrical feedback application circuits (most suitable in applications with dual, split supplies (e.g., 5v), ground referenced single-ended input signals and v ocm connected to ground) once the v ocm voltage is set to zero, the gain formula is the same as a standard noninverting op amp circuit multiplied by two to account for the complementary output. taking r fb to zero (i.e., taking to one) gives the same formula as the top circuit. as in the top circuit, this circuit is also useful as a single-ended output, high input impedance inverting gain block (this time with gain). the input com- mon mode considerations are similar to the top circuits, but are not nearly as constrained since there is now gain in the noninverting amplifier path. this circuit, with v ocm at ground, also permits a rail-to-rail output swing in most applications. the bottom circuit is another circuit that utilizes a standard op amp configuration with a complementary output. in this case, the standard op amp circuit has an inverting con- figuration. with v ocm at zero volts, the gain formula is the same as a standard inverting op amp circuit multiplied by two to account for the complementary output. this circuit does not have any common mode level constraints as the inverting input voltage sets the input common mode level. this circuit also delivers rail-to-rail output voltage swing without any concerns. a pplica t ions i n f or m a t ion ? ? + + +v out v outdiff = 2(+v in ? v ocm ) setting v ocm = 0v v outdiff = 2v in ?v out v in v ocm v ocm ltc1992 ? ? + + +v out r fb r in v outdiff = 2 setting v ocm = 0v v outdiff = 2v in ?v out v in v ocm r in r fb ( ) +v in ; b = = 2v in 1 + ? v ocm 1 b ( ) 1 b ( ) r in r in + r fb r fb r in ? ? + + +v out v outdiff = 2 setting v ocm = 0v v outdiff = 2v in ?v out 1992 f07 v in v ocm ( ) +v in ; b = = 2v in + v ocm 1 ? b b ( ) 1 ? b b ( ) r in r in + r fb r fb r in v ocm ltc1992 v ocm ltc1992
ltc1992 family 1992fa typical a pplica t ions interfacing a bipolar, ground referenced, single-ended signal to a unipolar single supply, differential input adc (v in = 0v gives a digital mid-scale code) compact, unipolar serial data conversion zero components, single-ended adder/subtracter ? ? + + ltc1992 3 6 v ocm v mid 0.1f 100pf 7 6 5 13.3k 40k 4 5 2 7 8 1 10k 10k 5v 13.3k 40k 5v 10k 10k 100 100 0.1f +in v ref v cc 2 1 8 3 4 1992 ta02a ?in 1f sck sdo conv ltc1864 serial data link gnd 0v v in 2.5v ?2.5v ? ? + + ltc1992-2 3 6 v ocm v mid 0.1f 100pf 7 6 5 4 5 2 7 8 1 100 5v 100 0.1f +in v ref v cc 2 1 8 3 4 1992 ta03a ?in 1f sck sdo conv ltc1864 serial data link gnd v in 2.5v 0v ? ? + + v1 = v b + v c ? v a v2 = v b + v a ? v c v a 1 4 0.1f 3 +v s ?v s 6 5 2 8 v c v b v ocm ltc1992-2 0.1f 1992 ta04
ltc1992 family 1992fa typical a pplica t ions single-ended to differential conversion driving an adc 2.2f 10f 10f 10 47f 4 6 refcomp 4.375v control logic and timing b15 to b0 16-bit sampling adc ? + 10f 5v or 3v p control lines d15 to d0 output buffers 16-bit parallel bus 11 to 26 1992 ta06a ognd ov dd 28 29 1 2 a in + a in ? shdn cs convst rd busy 33 32 31 30 27 ltc1603 3 36 35 10 9 5v 5v av dd av dd 7.5k dv dd dgnd v ref 8 agnd agnd 7 agnd 5 agnd 34 ?5v v ss 10f 2.5v ref 10f 1.75x + + + + + + ? ? + + 5v ?5v ltc1992-1 3 6 v ocm v mid v in 100pf 4 5 2 7 8 1 100 100 0.1f 0.1f fft of the output data snr =85.3db thd = ?72.1db sinad = ?72db f in = 10.0099khz f sample = 333khz 0 ?10 ?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100 ?110 ?120 ?130 ?140 frequency (khz) 0 amplitude (db) 8070 1992 ta06b 2010 4030 6050 10090
ltc1992 family 0 1992fa p ackage descrip t ion ms8 package 8-lead plastic msop (reference ltc dwg # 05-08-1660 rev f) msop (ms8) 0307 rev f 0.53 p 0.152 (.021 p .006) seating plane note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 0.18 (.007) 0.254 (.010) 1.10 (.043) max 0.22 ? 0.38 (.009 ? .015) typ 0.1016 p 0.0508 (.004 p .002) 0.86 (.034) ref 0.65 (.0256) bsc 0o ? 6o typ detail ?a? detail ?a? gauge plane 1 2 3 4 4.90 p 0.152 (.193 p .006) 8 7 6 5 3.00 p 0.102 (.118 p .004) (note 3) 3.00 p 0.102 (.118 p .004) (note 4) 0.52 (.0205) ref 5.23 (.206) min 3.20 ? 3.45 (.126 ? .136) 0.889 p 0.127 (.035 p .005) recommended solder pad layout 0.42 p 0.038 (.0165 p .0015) typ 0.65 (.0256) bsc
ltc1992 family 1992fa information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. r evision h is t ory rev date description page number a 7/10 updated part markings 2
ltc1992 family 1992fa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2005 lt 0710 rev a ? printed in usa r ela t e d p ar t s typical a pplica t ion part number description comments lt1167 precision instrumentation amplifier single resistor sets the gain lt1990 high voltage, gain selectable difference amplifier 250v common mode, micropower, selectable gain = 1, 10 lt1991 precision gain selectable difference amplifier micropower, pin selectable gain = C13 to 14 lt1995 high speed gain selectable difference amplifier 30mhz, 1000v/s, pin selectable gain = C7 to 8 lt6600-x differential in/out amplifier lowpass filter very low noise, standard differential amplifier pinout bnc v inp ? ? + + 1 4 7 8 11 4 12 17 13 14 16 0.1f v + 1/2 ltc1043 3 5v ?5v 6 5 2 8 v ocm 7 bnc v inp v ocm v mid ltc1992 0.1f 0.1f clk v ? 0.1f 1992 ta05a 0.1f clk 0.1f ? ? + + 1 4 3 6 5 2 8 v ocm 7 v mid ltc1992 bnc v outm bnc v outp 60khz low pass filter sampler 2khz lowpass filter 9.53k 9.53k 9.53k 37.4k 60.4k 37.4k 60.4k 9.53k 8.87k 8.87k 75k 75k 120pf 120pf 390pf 390pf 330pf 180pf 0.1f 10k balanced frequency converter (suitable for frequencies up to 50khz) 0v 0v 0v 0v 200s/div v inp = 24khz (1v/div) v outp = 1khz (0.5v/div) v outm = 1khz (0.5v/div) clk = 25khz (logic square wave) (5v/div) 1992 ta05b

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