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1 lt1207 dual 250ma/60mhz current feedback amplifier s f ea t u re n 250ma minimum output drive current n 60mhz bandwidth, a v = 2, r l = 100 w n 900v/ m s slew rate, a v = 2, r l = 50 w n 0.02% differential gain, a v = 2, r l = 30 w n 0.17 differential phase, a v = 2, r l = 30 w n high input impedance: 10m w n shutdown mode: i s < 200 m a per amplifier n stable with c l = 10,000pf applicatio s u n adsl/hdsl drivers n video amplifiers n cable drivers n rgb amplifiers n test equipment amplifiers n buffers the lt ? 1207 is a dual version of the lt1206 high speed current feedback amplifier. like the lt1206, each cfa in the dual has excellent video characteristics: 60mhz band- width, 250ma minimum output drive current, 400v/ m s minimum slew rate, low differential gain (0.02% typ) and low differential phase (0.17 typ). the lt1207 includes a pin for an optional compensation network which stabi- lizes the amplifier for heavy capacitive loads. both ampli- fiers have thermal and current limit circuits which protect against fault conditions. t hese capabilities make the lt1207 well suited for driving difficult loads such as cables in video or digital communication systems. operation is fully specified from 5v to 15v supplies. supply current is typically 20ma per amplifier. two micropower shutdown controls place each amplifier in a high impedance low current mode, dropping supply current to 200 m a per amplifier. for reduced bandwidth applications, supply current can be lowered by adding a resistor in series with the shutdown pin. the lt1207 is manufactured on linear technology's complementary bipolar process and is available in a low thermal resistance 16-lead so package. , ltc and lt are registered trademarks of linear technology corporation. typical applicatio n u d u escriptio hdsl driver + 1/2 lt1207 + 240 720 720 720 15k 15k v in + 0.1 f* 2.2 f** 5v + 0.1 f* 2.2 f** ?v 62 62 l1 1207 ?ta01 1/2 lt1207 shdn a shdn b ceramic tantalum l1 = transpower smpt?08 or similar device * **
2 lt1207 a u g w a w u w a r b s o lu t exi t i s wu u package / o rder i for atio supply voltage ..................................................... 18v input current per amplifier ............................... 15ma output short-circuit duration (note 1) ....... continuous specified temperature range (note 2) ...... 0 c to 70 c operating temperature range ............... C 40 c to 85 c junction temperature ......................................... 150 c storage temperature range ................. C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c order part number LT1207CS consult factory for industrial and military grade parts. q ja = 40 c/w (note 3) v cm = 0, 5v v s 15v, pulse tested, v shdn a = 0v, v shdn b = 0v, unless otherwise noted. electrical characteristics symbol parameter conditions min typ max units v os input offset voltage t a = 25 c 3 10 mv l 15 mv input offset voltage drift l 10 m v/ c i in + noninverting input current t a = 25 c 2 5 m a l 20 m a i in C inverting input current t a = 25 c 10 60 m a l 100 m a e n input noise voltage density f = 10khz, r f = 1k, r g = 10 w , r s = 0 w 3.6 nv/ ? hz +i n input noise current density f = 10khz, r f = 1k, r g = 10 w , r s = 10k 2 pa/ ? hz Ci n input noise current density f = 10khz, r f = 1k, r g = 10 w , r s = 10k 30 pa/ ? hz r in input resistance v in = 12v, v s = 15v l 1.5 10 m w v in = 2v, v s = 5v l 0.5 5 m w c in input capacitance v s = 15v 2 pf input voltage range v s = 15v l 12 13.5 v v s = 5v l 2 3.5 v cmrr common mode rejection ratio v s = 15v, v cm = 12v l 55 62 db v s = 5v, v cm = 2v l 50 60 db inverting input current v s = 15v, v cm = 12v l 0.1 10 m a/v common mode rejection v s = 5v, v cm = 2v l 0.1 10 m a/v psrr power supply rejection ratio v s = 5v to 15v l 60 77 db top view s package 16-lead plastic so 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 v + in a +in a shdn a in b +in b shdn b v + v + out a v a comp a out b v b comp b v +
3 lt1207 v cm = 0, 5v v s 15v, pulse tested, v shdn a = 0v, v shdn b = 0v, unless otherwise noted. electrical characteristics symbol parameter conditions min typ max units noninverting input current v s = 5v to 15v l 30 500 na/v power supply rejection inverting input current v s = 5v to 15v l 0.7 5 m a/v power supply rejection a v large-signal voltage gain v s = 15v, v out = 10v, r l = 50 w l 55 71 db v s = 5v, v out = 2v, r l = 25 w l 55 68 db r ol transresistance, d v out / d i in C v s = 15v, v out = 10v, r l = 50 w l 100 260 k w v s = 5v, v out = 2v, r l = 25 w l 75 200 k w v out maximum output voltage swing v s = 15v, r l = 50 w , t a = 25 c 11.5 12.5 v l 10.0 v v s = 5v, r l = 25 w , t a = 25 c 2.5 3.0 v l 2.0 v i out maximum output current r l = 1 w l 250 500 1200 ma i s supply current per amplifier v s = 15v, v shdn = 0v, t a = 25 c2030ma l 35 ma supply current per amplifier, v s = 15v, t a = 25 c1217ma r shdn = 51k (note 4) positive supply current v s = 15v, v shdn a = 15v, v shdn b = 15v l 200 m a per amplifier, shutdown output leakage current, shutdown v s = 15v, v shdn = 15v, v out = 0v l 10 m a sr slew rate (note 5) a v = 2, t a = 25 c 400 900 v/ m s differential gain (note 6) v s = 15v, r f = 560 w , r g = 560 w , r l = 30 w 0.02 % differential phase (note 6) v s = 15v, r f = 560 w , r g = 560 w , r l = 30 w 0.17 deg bw small-signal bandwidth v s = 15v, peaking 0.5db 60 mhz r f = r g = 620 w , r l = 100 w v s = 15v, peaking 0.5db 52 mhz r f = r g = 649 w , r l = 50 w v s = 15v, peaking 0.5db 43 mhz r f = r g = 698 w , r l = 30 w v s = 15v, peaking 0.5db 27 mhz r f = r g = 825 w , r l = 10 w note 3: thermal resistance q ja varies from 40 c/w to 60 c/w depending upon the amount of pc board metal attached to the device. q ja is specified for a 2500mm 2 test board covered with 2oz copper on both sides. note 4: r shdn is connected between the shutdown pin and ground. note 5: slew rate is measured at 5v on a 10v output signal while operating on 15v supplies with r f = 1.5k, r g = 1.5k and r l = 400 w . note 6: ntsc composite video with an output level of 2v. the l denotes specifications which apply for 0 c t a 70 c. note 1: applies to short circuits to ground only. a short circuit between the output and either supply may permanently damage the part when operated on supplies greater than 10v. note 2: commercial grade parts are designed to operate over the temperature range of C 40 c to 85 c but are neither tested nor guaranteed beyond 0 c to 70 c. industrial grade parts tested over C 40 c to 85 c are available on special request. consult factory.
4 lt1207 s all - sig al ba dwidth wu u i s = 20ma per amplifier typical, peaking 0.1db i s = 10ma per amplifier typical, peaking 0.1db i s = 5ma per amplifier typical, peaking 0.1db C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 5v, r shdn = 22.1k C 1 150 604 604 21 10.5 30 715 715 14.6 7.4 10 681 681 10.5 6.0 1 150 768 C 20 9.6 30 866 C 14.1 6.7 10 825 C 9.8 5.1 2 150 634 634 20 9.6 30 750 750 14.1 7.2 10 732 732 9.6 5.1 10 150 100 11.1 16.2 5.8 30 100 11.1 13.4 7.0 10 100 11.1 9.5 4.7 C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 15v, r shdn = 121k C 1 150 619 619 25 12.5 30 787 787 15.8 8.5 10 825 825 10.5 5.4 1 150 845 C 23 10.6 30 1k C 15.3 7.6 10 1k C 10 5.2 2 150 681 681 23 10.2 30 845 845 15 7.7 10 866 866 10 5.4 10 150 100 11.1 15.9 4.5 30 100 11.1 13.6 6 10 100 11.1 9.6 4.5 C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 5v, r shdn = 0 w C 1 150 562 562 48 21.4 30 649 649 34 17 10 732 732 22 12.5 1 150 619 C 54 22.3 30 715 C 36 17.5 10 806 C 22.4 11.5 2 150 576 576 48 20.7 30 649 649 35 18.1 10 750 750 22.4 11.7 10 150 442 48.7 40 19.2 30 511 56.2 31 16.5 10 649 71.5 20 10.2 C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 15v, r shdn = 0 w C 1 150 681 681 50 19.2 30 768 768 35 17 10 887 887 24 12.3 1 150 768 C 66 22.4 30 909 C 37 17.5 10 1k C 23 12 2 150 665 665 55 23 30 787 787 36 18.5 10 931 931 22.5 11.8 10 150 487 536 44 20.7 30 590 64.9 33 17.5 10 768 84.5 20.7 10.8 C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 5v, r shdn = 10.2k C 1 150 576 576 35 17 30 681 681 25 12.5 10 750 750 16.4 8.7 1 150 665 C 37 17.5 30 768 C 25 12.6 10 845 C 16.5 8.2 2 150 590 590 35 16.8 30 681 681 25 13.4 10 768 768 16.2 8.1 10 150 301 33.2 31 15.6 30 392 43.2 23 11.9 10 499 54.9 15 7.8 C 3db bw C 0.1db bw a v r l r f r g (mhz) (mhz) v s = 15v, r shdn = 60.4k C 1 150 634 634 41 19.1 30 768 768 26.5 14 10 866 866 17 9.4 1 150 768 C 44 18.8 30 909 C 28 14.4 10 1k C 16.8 8.3 2 150 649 649 40 18.5 30 787 787 27 14.1 10 931 931 16.5 8.1 10 150 301 33.2 33 15.6 30 402 44.2 25 13.3 10 590 64.9 15.3 7.4
5 lt1207 typical perfor a ce characteristics wu bandwidth and feedback resistance vs capacitive load for 0.5db peak bandwidth vs supply voltage bandwidth vs supply voltage bandwidth vs supply voltage spot noise voltage and current vs frequency bandwidth and feedback resistance vs capacitive load for 5db peak 4 0 10 30 40 50 100 70 8 12 20 80 90 60 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) lt1207 ?tpc01 peaking 0.5db peaking 5db r f = 470 w r f = 560 w r f = 680 w r f = 750 w r f = 1k r f = 1.5k a v = 2 r l = 100 w 4 0 20 50 8 12 10 40 30 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) lt1207 ?tpc02 peaking 0.5db peaking 5db r f = 560 w r f = 1k r f = 2k r f = 750 w a v = 2 r l = 10 w 4 0 10 30 40 50 100 70 8 12 20 80 90 60 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) lt1207 ?tpc04 peaking 0.5db peaking 5db r f = 470 w r f = 1.5k r f = 330 w r f = 680 w r f =390 w a v = 10 r l = 100 w 4 0 20 50 8 12 10 40 30 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) lt1207 ?tpc05 peaking 0.5db peaking 5db r f = 560 w r f = 1k r f = 1.5k r f = 680 w a v = 10 r l = 10 w capacitive load (pf) feedback resistor ( w ) 1 lt1207 ?tpc06 10 100 1k 10k 0 3db bandwidth (mhz) 1k 10k 0 100 10 100 1 feedback resistor bandwidth a v = +2 r l = v s = 15v c comp = 0.01 m f frequency (hz) 10 1 10 100 100 100k lt1207 ?tpc09 1k 10k spot noise (nv/ ? hz or pa/ ? hz) i n e n ? n bandwidth vs supply voltage capacitive load (pf) 1 100 feedback resistor ( w ) 1k 10k 100 10000 lt1207 ?tpc03 10 1000 bandwidth feedback resistor a v = 2 r l = v s = 15v c comp = 0.01 m f 1 10 100 3db bandwidth (mhz) differential phase vs supply voltage differential gain vs supply voltage supply voltage ( v) 5 differential phase (deg) 0.30 0.40 0.50 13 lt1207 ?tpc07 0.20 0.10 0 7 9 11 15 r f = r g = 560 w a v = 2 n package r l = 15 w r l = 50 w r l = 30 w r l = 150 w supply voltage ( v) 5 differential gain (%) 0.06 0.08 0.10 13 lt1207 ?tpc08 0.04 0.02 0 7 9 11 15 r f = r g = 560 w a v = 2 n package r l = 15 w r l = 30 w r l = 150 w r l = 50 w
6 lt1207 supply current vs ambient temperature, v s = 15v output short-circuit current vs junction temperature supply current vs large-signal output frequency (no load) typical perfor a ce characteristics wu supply current vs shutdown pin current input common mode limit vs junction temperature output saturation voltage vs junction temperature power supply rejection ratio vs frequency supply current vs ambient temperature, v s = 5v 4 10 12 16 18 22 8 12 14 24 20 610 14 16 18 supply voltage ( v) supply current per amplifier (ma) lt1207 ?tpc10 t j = 40?c t j = 25?c t j = 85?c t j = 125?c v shdn = 0v temperature ( c) ?0 0 supply current per amplifier (ma) 10 25 0 50 75 lt1207 ?tpc11 5 20 15 ?5 25 100 125 a v = 1 r l = r sd = 0 w r sd = 10.2k r sd = 22.1k temperature ( c) ?0 0 supply current per amplifier (ma) 10 25 0 50 75 lt1207 ?tpc12 5 20 15 ?5 25 100 125 a v = 1 r l = r sd = 0 w r sd = 60.4k r sd = 121k temperature ( c) ?0 v common mode range (v) 0.5 1.5 2.0 2.0 75 v + lt1207 ?tpc14 1.0 0 125 1.5 1.0 0.5 50 ?5 100 25 shutdown pin current ( m a) 0 supply current per amplifier (ma) 12 16 20 400 lt1207 ?tpc13 8 4 0 100 200 300 500 10 14 18 6 2 v s = 15v temperature ( c) ?0 0.7 0.8 1.0 25 75 lt 1207 ?tpc15 0.6 0.5 ?5 0 50 100 125 0.4 0.3 0.9 output short-circuit current (a) sourcing sinking temperature ( c) ?0 v output saturation voltage (v) 1 3 4 ? 75 v + lt1207 ?tpc16 2 0 125 ? ? ? 50 ?5 100 25 v s = 15v r l = 2k r l = 50 w r l = 50 w r l = 2k frequency (hz) 20 power supply rejection (db) 40 60 70 10k 1m 10m 100m lt1207 ?tpc17 0 100k 50 30 10 r l = 50 w v s = 15v r f = r g = 1k negative positive supply current vs supply voltage frequency (hz) 10k supply current per amplifier (ma) 40 50 60 100k 1m 10m lt1207 ?tpc18 30 20 10 a v = 2 r l = v s = 15v v out = 20v p-p
7 lt1207 2nd and 3rd harmonic distortion vs frequency output impedance vs frequency typical perfor a ce characteristics wu output impedance in shutdown vs frequency frequency (hz) 0.1 output impedance ( w ) 1 10 100 100k 10m 100m lt1207 ?tpc19 0.01 1m v s = 15v i o = 0ma r shdn = 121k r shdn = 0 w frequency (hz) 100 output impedance ( w ) 1k 10k 100k 100k 10m 100m lt1207 ?tpc20 10 1m a v = 1 r f = 1k v s = 15v frequency (mhz) 1 ?0 distortion (dbc) ?0 ?0 ?0 ?0 ?0 310 lt1207 ?tpc21 ?0 2456789 v s = 15v v o = 2v p-p 2nd 3rd r l = 10 w 2nd 3rd r l = 30 w test circuit for 3rd order intercept 3rd order intercept vs frequency frequency (mhz) 0 10 3rd order intercept (dbm) 20 30 40 50 60 5 10 15 20 lt1207 ?tpc22 25 30 v s = 15v r l = 50 w r f = 590 w r g = 64.9 w + 50 w 1/2 lt1207 lt1207 ?tpc23 65 w 590 w p o measure intercept at p o
8 lt1207 si plified sche atic ww lt1207 ?ss v output v + 50 w d2 d1 v v + v + v c c r c comp ?n +in shutdown 1.25k to all current sources q11 q15 q9 q6 q5 q2 q1 q18 q17 q3 q4 q7 q8 q12 q16 q14 q13 q10 1/2 lt1207 current feedback amplifier u s a o pp l ic at i wu u i for atio the lt1207 is a dual current feedback amplifier with high output current drive capability. the device is stable with large capacitive loads and can easily supply the high currents required by capacitive loads. the amplifier will drive low impedance loads such as cables with excellent linearity at high frequencies. feedback resistor selection the optimum value for the feedback resistors is a function of the operating conditions of the device, the load imped- ance and the desired flatness of response. the typical ac performance tables give the values which result in the highest 0.1db and 0.5db bandwidths for various resistive loads and operating conditions. if this level of flatness is not required, a higher bandwidth can be obtained by use of a lower feedback resistor. the characteristic curves of bandwidth vs supply voltage indicate feedback resistors for peaking up to 5db. these curves use a solid line when the response has less than 0.5db of peaking and a dashed line when the response has 0.5db to 5db of peaking. the curves stop where the response has more than 5db of peaking. for resistive loads, the comp pin should be left open (see section on capacitive loads). capacitive loads each amplifier in the lt1207 includes an optional com- pensation network for driving capacitive loads. this net- work eliminates most of the output stage peaking associ- ated with capacitive loads, allowing the frequency re- sponse to be flattened. figure 1 shows the effect of the network on a 200pf load. without the optional compensa- tion, there is a 5db peak at 40mhz caused by the effect of the capacitance on the output stage. adding a 0.01 m f bypass capacitor between the output and the comp pins connects the compensation and completely eliminates the peaking. a lower value feedback resistor can now be used, resulting in a response which is flat to 0.35db to 30mhz.
9 lt1207 u s a o pp l ic at i wu u i for atio frequency (mhz) 1 ? voltage gain (db) ? 0 4 8 10 100 lt1207 ?f01 ? ? 2 6 10 12 v s = 15v r f = 1.2k compensation r f = 2k no compensation r f = 2k compensation figure 1. the network has the greatest effect for c l in the range of 0pf to 1000pf. the graph of maximum capacitive load vs feedback resistor can be used to select the appropriate value of the feedback resistor. the values shown are for 0.5db and 5db peaking at a gain of 2 with no resistive load. this is a worst-case condition, as the amplifier is more stable at higher gains and with some resistive load in parallel with the capacitance. also shown is the C 3db bandwidth with the suggested feedback resistor vs the load capacitance. although the optional compensation works well with capacitive loads, it simply reduces the bandwidth when it is connected with resistive loads. for instance, with a 30 w load, the bandwidth drops from 55mhz to 35mhz when the compensation is connected. hence, the compensation was made optional. to disconnect the optional compensa- tion, leave the comp pin open. shutdown/current set if the shutdown feature is not used, the shutdown pins must be connected to ground or v C . each amplifier has a separate shutdown pin which can be used to either turn off the amplifier, which reduces the amplifier supply current to less than 200 m a, or to control the supply current in normal operation. the supply current in each amplifier is controlled by the current flowing out of the shutdown pin. when the shut- down pin is open or driven to the positive supply, the amplifier is shut down. in the shutdown mode, the output looks like a 40pf capacitor and the supply current is typically 100 m a. each shutdown pin is referenced to the positive supply through an internal bias circuit (see the simplified schematic). an easy way to force shutdown is to use open drain (collector) logic. the circuit shown in figure 2 uses a 74c904 buffer to interface between 5v logic and the lt1207. the switching time between the active and shutdown states is less than 1 m s. a 24k pull-up resistor speeds up the turn-off time and insures that the amplifier is completely turned off. because the pin is referenced to the positive supply, the logic used should have a breakdown voltage of greater than the positive supply voltage. no other circuitry is necessary as the internal circuit limits the shutdown pin current to about 500 m a. figure 3 shows the resulting waveforms. figure 2. shutdown interface + 1/2 lt1207 shdn 15v 15v r f r g v in 5v 24k enable v out lt1207 ?f02 15v 74c906 for applications where the full bandwidth of the amplifier is not required, the quiescent current may be reduced by connecting a resistor from the shutdown pin to ground. figure 3. shutdown operation lt1207 ? f3 a v = 1 r f = 825 w r l = 50 w r pu = 24k v in = 1v p-p enable v out
10 lt1207 u s a o pp l ic at i wu u i for atio and for higher gains in the noninverting mode, the signal amplitude on the input pins is small and the overall slew rate is that of the output stage. the input stage slew rate is related to the quiescent current and will be reduced as the supply current is reduced. the output slew rate is set by the value of the feedback resistors and the internal capacitance. larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced. the photos (figures 5a, 5b and 5c) show the large-signal response of the lt1207 or various gain configurations. the slew rate varies from 860v/ m s for a gain of 1, to 1400v/ m s for a gain of C 1. when the lt1207 is used to drive capacitive loads, the available output current can limit the overall slew rate. in the fastest configuration, the lt1207 is capable of a slew rate of over 1v/ns. the current required to slew a capacitor figure 5b. large-signal response, a v = C1 lt1207 ? f05b r f = rg = 750 w r l = 50 w v s = 15v the amplifiers supply current will be approximately 40 times the current in the shutdown pin. the voltage across the resistor in this condition is v + C 3v be . for example, a 60k resistor will set the amplifiers supply current to 10ma with v s = 15v. the photos (figures 4a and 4b) show the effect of reducing the quiescent supply current on the large-signal response. the quiescent current can be reduced to 5ma in the inverting configuration without much change in response. in noninverting mode, however, the slew rate is reduced as the quiescent current is reduced. figure 4a. large-signal response vs i q , a v = C1 figure 4b. large-signal response vs i q , a v = 2 lt1207 ? f04a r f = 750 w r l = 50 w i q = 5ma, 10ma, 20ma v s = 15v lt1207 ? f04b r f = 750 w r l = 50 w i q = 5ma, 10ma, 20ma v s = 15v slew rate unlike a traditional op amp, the slew rate of a current feedback amplifier is not independent of the amplifier gain configuration. there are slew rate limitations in both the input stage and the output stage. in the inverting mode, lt1207 ? f05a r f = 825 w r l = 50 w v s = 15v figure 5a. large-signal response, a v = 1
11 lt1207 figure 5c. large-signal response, a v = 2 capacitance on the inverting input current feedback amplifiers require resistive feedback from the output to the inverting input for stable operation. take care to minimize the stray capacitance between the output and the inverting input. capacitance on the invert- ing input to ground will cause peaking in the frequency response (and overshoot in the transient response), but it does not degrade the stability of the amplifier. power supplies the lt1207 will operate from single or split supplies from 5v (10v total) to 15v (30v total). it is not necessary to use equal value split supplies, however the offset voltage and inverting input bias current will change. the offset voltage changes about 500 m v per volt of supply mis- match. the inverting bias current can change as much as 5 m a per volt of supply mismatch, though typically the change is less than 0.5 m a per volt. thermal considerations each amplifier in the lt1207 includes a separate thermal shutdown circuit which protects against excessive inter- nal (junction) temperature. if the junction temperature exceeds the protection threshold, the amplifier will begin cycling between normal operation and an off state. the cycling is not harmful to the part. the thermal cycling occurs at a slow rate, typically 10ms to several seconds, which depends on the power dissipation and the thermal time constants of the package and heat sinking. raising the ambient temperature until the device begins thermal shutdown gives a good indication of how much margin there is in the thermal design. heat flows away from the amplifier through the packages copper lead frame. heat sinking is accomplished by using the heat spreading capabilities of the pc board and its copper traces. experiments have shown that the heat spreading copper layer does not need to be electrically connected to the tab of the device. the pcb material can be very effective at transmitting heat between the pad area attached to the tab of the device and a ground or power plane layer either inside or on the opposite side of the board. although the actual thermal resistance of the pcb material is high, the length/area ratio of the thermal u s a o pp l ic at i wu u i for atio lt1207 ? f05c r f = 750 w r l = 50 w differential input signal swing the differential input swing is limited to about 6v by an esd protection device connected between the inputs. in normal operation, the differential voltage between the input pins is small, so this clamp has no effect; however, in the shutdown mode the differential swing can be the same as the input swing. the clamp voltage will then set the maximum allowable input voltage. to allow for some margin, it is recommended that the input signal be less than 5v when the device is shut down. lt1207 ? f06 figure 6. large-signal response, c l = 10,000pf v s = 15v r f = rg = 3k r l = at this rate is 1ma per picofarad of capacitance, so 10,000pf would require 10a! the photo (figure 6) shows the large-signal behavior with c l = 10,000pf. the slew rate is about 60v/ m s, determined by the current limit of 600ma.
12 lt1207 resistance between the layer is small. copper board stiff- eners and plated through holes can also be used to spread the heat generated by the device. table 1 lists thermal resistance for several different board sizes and copper areas. all measurements were taken in still air on 3/32" fr-4 board with 2oz copper. this data can be used as a rough guideline in estimating thermal resis- tance. the thermal resistance for each application will be affected by thermal interactions with other components as well as board size and shape. table 1. fused 16-lead so package total thermal resistance topside backside copper area (junction-to-ambient) 2500 sq. mm 2500 sq. mm 5000 sq. mm 40 c/w 1000 sq. mm 2500 sq. mm 3500 sq. mm 46 c/w 600 sq. mm 2500 sq. mm 3100 sq. mm 48 c/w 180 sq. mm 2500 sq. mm 2680 sq. mm 49 c/w 180 sq. mm 1000 sq. mm 1180 sq. mm 56 c/w 180 sq. mm 600 sq. mm 780 sq. mm 58 c/w 180 sq. mm 300 sq. mm 480 sq. mm 59 c/w 180 sq. mm 100 sq. mm 280 sq. mm 60 c/w 180 sq. mm 0 sq. mm 180 sq. mm 61 c/w where: t j = junction temperature t a = ambient temperature p d = device dissipation q ja = thermal resistance (junction-to-ambient) as an example, calculate the junction temperature for the circuit in figure 8 assuming a 70 c ambient temperature. the device dissipation can be found by measuring the supply currents, calculating the total dissipation and then subtracting the dissipation in the load and feedback network. u s a o pp l ic at i wu u i for atio the dissipation for each amplifier is: p d = (37.5ma)(30v) C (12v) 2 /(1k||1k) = 0.837w the total dissipation is p d = 1.674w. when a 2500 sq mm pc board with 2oz copper on top and bottom is used, the thermal resistance is 40 c/w. the junction temperature t j is: t j = (1.674w)(40 c/w) + 70 c = 137 c the maximum junction temperature for the lt1207 is 150 c, so the heat sinking capability of the board is adequate for the application. if the copper area on the pc board is reduced to 280mm 2 the thermal resistance increases to 60 c/w and the junc- tion temperature becomes: t j = (1.674w)(60 c/w) + 70 c = 170 c which is above the maximum junction temperature indi- cating that the heat sinking capability of the board is inadequate and should be increased. copper area (2oz) copper area (mm 2 ) 0 thermal resistance ( c/w) 70 60 50 40 30 20 10 0 lt1207 ?f07 2000 5000 1000 3000 4000 figure 7. thermal resistance vs total copper area (top + bottom) calculating junction temperature the junction temperature can be calculated from the equation: t j = (p d )( q ja ) + t a + 15v 15v 0.01 m f 1k 330 w 1k 200pf 12v 12v f = 2mhz 37.5ma i lt1206 ?f07 1/2 lt1207 shdn figure 8. thermal calculation example
13 lt1207 typical applicatio s u + lt1097 + 1/2 lt1207 v in shdn comp 0.01 m f 3k 330 w 10k 1k out output offset: < 500 m v slew rate: 2v/ m s bandwidth: 4mhz stable with c l < 10nf lt1207 ?ta02 500pf + lt1115 1 m f 15v 1 m f 15v 68pf 1 m f 15v 1 m f + 1/2 lt1207 0.01 m f 15v 560 w 560 w 909 w 100 w r l output r l = 32 w v o = 5v rms thd + noise = 0.0009% at 1khz = 0.004% at 20khz small-signal 0.1db bandwidth = 600khz lt1207 ?ta03 shdn + + + + gain of eleven high current amplifier gain of ten buffered line driver
14 lt1207 typical applicatio s u + 1/2 lt1207 shdn ?5v 15v 24k 10k 5v 2n3904 lt1207 ?ta04 cmos logic to shutdown interface + 1/2 lt1207 shdn 75 w v in r f r g 75 w 75 w 75 w 75 w 75 w cable lt1207 ?ta05 distribution amplifier differential inputdifferential output power amplifier (a v = 4) buffer a v = 1 + 1/2 lt1207 shdn 0.01 m f* v out r f ** v in lt1207 ?ta06 optional, use with capacitive loads value of r f depends on supply voltage and loading. select from typical ac performance table or determine empirically * ** comp differential output driver + + 1k 1k 1k 0.01 f 0.01 f 500 + v in v out lt1207 ?ta07 1/2 lt1207 1/2 lt1207 + + 1k 1k 1k + + v out v in lt1207 ?ta08 1/2 lt1207 1/2 lt1207
15 lt1207 typical applicatio s u + + 1k 1k 3 3 1k 1k v in v out lt1207 ?ta09 1/2 lt1207 1/2 lt1207 paralleling both cfas for guaranteed 500ma output drive current package descriptio u dimensions in inches (millimeters) unless otherwise noted. 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010 (0.203 ?0.254) 1 2 3 4 5 6 7 8 0.150 ?0.157** (3.810 ?3.988) 16 15 14 13 0.386 ?0.394* (9.804 ?10.008) 0.228 ?0.244 (5.791 ?6.197) 12 11 10 9 s16 0695 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) typ dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side * ** s package 16-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) 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 represen- tation that the interconnection of circuits as described herein will not infringe on existing patent rights.
16 lt1207 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax : (408) 434-0507 l telex : 499-3977 ? linear technology corporation 1996 lt/gp 0196 10k ? printed in usa related parts part number description comments lt1206 single 250ma/60mhz current feedback amplifier single version of lt1207, 900v/ m s slew rate, 0.02% differential gain, 0.17 differential phase, with a v = 2 and r l = 30 w , stable with c l = 10,000pf, shutdown control reduces supply current to 200 m a lt1210 single 1a/30mhz current feedback amplifier higher output current version of lt1206 lt1229/lt1230 dual/quad 100mhz current feedback amplifiers low cost cfa for video applications, 1000v/ m s slew rate, 30ma output drive current, 0.04% differential gain, 0.1 differential phase, with a v = 2 and r l = 150 w , 9.5ma max supply current per op amp, 2v to 15v supply range lt1360/lt1361/lt1362 single/dual/quad 50mhz, 800v/ m s, fast settling voltage feedback amplifier, 60ns settling time to 0.1%, c-load tm op amps 10v step, 5ma max supply current per op amp, 9nv ? hz input noise voltage, drives all capacitive loads, 1mv max v os , 0.2% differential gain, 0.3 differential phase with a v = 2 and r l = 150 w c-load is a trademark of linear technology corporation ccd clock driver. two 3rd order gaussian filters produce clean ccd clock signals clk d q q clock input 1k 100pf 1k 1k 91pf + 1k 0.01 f 510 20v 45pf 1k 100pf 1k 1k 91pf + 1k 0.01 f 510 ?0v 45pf 10 10 3300pf 3300pf ccd array load lt1207 ?ta10 5 0 clock input 15 0 driver output 74hc74 1/2 lt1207 1/2 lt1207 typical applicatio n u

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