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1 lt1210 1.1a, 35mhz current feedback amplifier d u escriptio s f ea t u re n 1.1a minimum output drive current n 35mhz bandwidth, a v = 2, r l = 10 w n 900v/ m s slew rate, a v = 2, r l = 10 w n high input impedance: 10m w n wide supply range: 5v to 15v (to-220 and dd packages) n enhanced q ja so-16 package for 5v operation n shutdown mode: i s < 200 m a n adjustable supply current n stable with c l = 10,000pf the lt ? 1210 is a current feedback amplifier with high output current and excellent large-signal characteristics. the combination of high slew rate, 1.1a output drive and 15v operation enables the device to deliver significant power at frequencies in the 1mhz to 2mhz range. short- circuit protection and thermal shutdown ensure the devices ruggedness. the lt1210 is stable with large capacitive loads, and can easily supply the large currents required by the capacitive loading. a shutdown feature switches the device into a high impedance and low supply current mode, reducing dissipation when the device is not in use. for lower bandwidth applications, the supply current can be reduced with a single external resistor. the lt1210 is available in the to-220 and dd packages for operation with supplies up to 15v. for 5v applica- tions the device is also available in a low thermal resis- tance so-16 package. n cable drivers n buffers n test equipment amplifiers n video amplifiers n adsl drivers applicatio n s u typical applicatio s u + + lt1210 v in + 4.7 m f* 4.7 m f* 100nf 1210 ta01 r t 11 w 2.5w t1** 845 w 3 1 274 w 100nf sd 15v 15v * tantalum ** midcom 671-7783 or equivalent r l 100 w 2.5w total harmonic distortion vs frequency frequency (hz) 1k total harmonic distortion (db) 50 60 70 80 90 100 10k 100k 1m 1210 ta02 v s = 15v v out = 20v p-p a v = 4 r l = 10 w r l = 50 w r l = 12.5 w twisted pair driver , ltc and lt are registered trademarks of linear technology corporation.
2 lt1210 a u g w a w u w a r b s o lu t exi t i s supply voltage ..................................................... 18v input current .................................................... 15ma output short-circuit duration (note 1) ....... continuous specified temperature range (note 2) ...... 0 c to 70 c operating temperature range ............... C40 c to 85 c junction temperature ......................................... 150 c storage temperature range ................. C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c symbol parameter conditions min typ max units v os input offset voltage t a = 25 c 3 15 mv l 20 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 3.0 nv/ ? hz +i n input noise current density f = 10khz, r f = 1k, r g = 10 w , r s = 10k 2.0 pa/ ? hz Ci n input noise current density f = 10khz, r f = 1k, r g = 10 w , r s = 10k 40 pa/ ? hz r in input resistance v in = 12v, v s = 15v l 1.50 10 m w v in = 2v, v s = 5v l 0.25 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 v cm = 0v, 5v v s 15v, pulse tested, v sd = 0v, unless otherwise noted. electrical characteristics 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 + v + out v + nc in nc v + v + nc v comp shutdown +in nc v + q ja ? 40 c/w (note 3) q ja ? 25 c/w r package 7-lead plastic dd front view out v comp v + shutdown +in ?n 7 6 5 4 3 2 1 tab is v + t7 package 7-lead to-220 out v comp v + shutdown +in ?n front view 7 6 5 4 3 2 1 tab is v + q jc = 5 c/w order part number LT1210CR lt1210ct7 order part number order part number lt1210cs consult factory for industrial and military grade parts. package/order i n for m atio n w u u
3 lt1210 symbol parameter conditions min typ max units 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 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 t a = 25 c, v s = 15v, v out = 10v, 55 71 db r l = 10 w (note 3) v s = 15v, v out = 8.5v, r l = 10 w (note 3) l 55 68 db v s = 5v, v out = 2v, r l = 10 w l 55 68 db r ol transresistance, d v out / d i in C t a = 25 c, v s = 15v, v out = 10v, r l = 10 w (note 3) 100 260 k w v s = 15v, v out = 8.5v, r l = 10 w (note 3) l 75 200 k w v s = 5v, v out = 2v, r l = 10 w l 75 200 k w v out maximum output voltage swing t a = 25 c, v s = 15v, r l = 10 w (note 3) 10.0 11.5 v l 8.5 v t a = 25 c, v s = 5v, r l = 10 w 2.5 3.0 v l 2.0 v i out maximum output current (note 3) v s = 15v, r l = 1 w l 1.1 2.0 a i s supply current (note 3) t a = 25 c, v s = 15v, v sd = 0v 35 50 ma l 65 ma supply current, r sd = 51k (notes 3, 4) t a = 25 c, v s = 15v 15 30 ma positive supply current, shutdown v s = 15v, v sd = 15v l 200 m a output leakage current, shutdown v s = 15v, v sd = 15v l 10 m a sr slew rate (note 5) t a = 25 c, a v = 2, r l = 400 w 400 900 v/ m s slew rate (note 3) t a = 25 c, a v = 2, r l = 10 w 900 v/ m s differential gain (notes 3, 6) v s = 15v, r f = 750 w , r g = 750 w , r l = 15 w 0.3 % differential phase (notes 3, 6) v s = 15v, r f = 750 w , r g = 750 w , r l = 15 w 0.1 deg bw small-signal bandwidth a v = 2, v s = 15v, peaking 1db, 55 mhz r f = r g = 680 w , r l = 100 w a v = 2, v s = 15v, peaking 1db, 35 mhz r f = r g = 576 w , r l = 10 w electrical characteristics v cm = 0v, 5v v s 15v, pulse tested, v sd = 0v, unless otherwise noted. supply voltages greater than 5v, use the to-220 or dd package. see thermal considerations in the applications information section for details on calculating junction temperature. if the maximum dissipation of the package is exceeded, the device will go into thermal shutdown. note 4: r sd 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 t a 85 c, but are neither tested nor guaranteed beyond 0 c t a 70 c. industrial grade parts tested over C40 c t a 85 c are available on special request. consult factory. note 3: so package is recommended for 5v supplies only, as the power dissipation of the so package limits performance on higher supplies. for
4 lt1210 r sd = 0 w , i s = 30ma, v s = 5v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 549 549 52.5 30 590 590 39.7 10 619 619 26.5 1 150 604 C 53.5 30 649 C 39.7 10 619 C 27.4 2 150 562 562 51.8 30 590 590 38.8 10 576 576 27.4 10 150 392 43.2 48.4 30 383 42.2 40.3 10 215 23.7 36.0 r sd = 0 w , i s = 35ma, v s = 15v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 604 604 66.2 30 649 649 48.4 10 665 665 46.5 1 150 750 C 56.8 30 866 C 35.4 10 845 C 24.7 2 150 665 665 52.5 30 715 715 38.9 10 576 576 35.0 10 150 453 49.9 61.5 30 432 47.5 43.1 10 221 24.3 45.5 r sd = 7.5k, i s = 15ma, v s = 5v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 562 562 39.7 30 619 619 28.9 10 604 604 20.5 1 150 634 C 41.9 30 681 C 29.7 10 649 C 20.7 2 150 576 576 40.2 30 604 604 29.6 10 576 576 21.6 10 150 324 35.7 39.5 30 324 35.7 32.3 10 210 23.2 27.7 r sd = 47.5k, i s = 18ma, v s = 15v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 619 619 47.8 30 698 698 32.3 10 698 698 22.2 1 150 732 C 51.4 30 806 C 33.9 10 768 C 22.5 2 150 634 634 48.4 30 698 698 33.0 10 681 681 22.5 10 150 348 38.3 46.8 30 357 39.2 36.7 10 205 22.6 31.3 r sd = 15k, i s = 7.5ma, v s = 5v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 536 536 28.2 30 549 549 20.0 10 464 464 15.0 1 150 619 C 28.6 30 634 C 19.8 10 511 C 14.9 2 150 536 536 28.3 30 549 549 19.9 10 412 412 15.7 10 150 150 16.5 31.5 30 118 13.0 27.1 10 100 11.0 19.4 r sd = 82.5k, i s = 9ma, v s = 15v, peaking 1db C 3db bw a v r l r f r g (mhz) C 1 150 590 590 34.8 30 649 649 22.5 10 576 576 16.3 1 150 715 C 35.5 30 768 C 22.5 10 649 C 16.1 2 150 590 590 35.3 30 665 665 22.5 10 549 549 16.8 10 150 182 20.0 37.2 30 182 20.0 28.9 10 100 11.0 22.5 s m all-sig n al ba n dwidth u u w
5 lt1210 typical perfor a ce characteristics wu bandwidth vs supply voltage 4 0 20 50 8 12 10 40 30 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) 1210 g02 peaking 1db 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) 1210 g01 peaking 1db peaking 5db r f = 470 w r f = 560 w r f = 750 w r f = 1k r f = 1.5k a v = 2 r l = 100 w r f = 680 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) 1210 g04 peaking 1db 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 bandwidth vs supply voltage 4 0 20 50 8 12 10 40 30 610 14 16 18 supply voltage ( v) 3db bandwidth (mhz) 1210 g05 peaking 1db r f = 560 w r f = 1k r f = 1.5k a v = 10 r l = 10 w r f = 680 w bandwidth and feedback resistance vs capacitive load for peaking 5db differential phase vs supply voltage supply voltage ( v) 5 differential phase (deg) 0.6 0.5 0.4 0.3 0.2 0.1 0 13 1210 g07 7 9 11 15 r f = r g = 750 w a v = 2 r l = 10 w r l = 50 w r l = 15 w r l = 30 w differential gain vs supply voltage supply voltage ( v) 5 differential gain (%) 0.5 0.4 0.3 0.2 0.1 0 13 1210 g08 7 9 11 15 r f = r g = 750 w a v = 2 r l = 10 w r l = 15 w r l = 30 w r l = 50 w spot noise voltage and current vs frequency capacitive load (pf) 100 feedback resistance ( w ) 1k 10k 100 10 1 10000 1210 g03 1000 bandwidth feedback resistance a v = 2 r l = v s = 15v c comp = 0.01 m f 1 10 100 3db bandwidth (mhz) capacitive load (pf) feedback resistance ( w ) 1 1210 g06 10 100 1000 10000 0 3db bandwidth (mhz) 1k 10k 0 100 10 100 1 feedback resistance bandwidth a v = +2 r l = v s = 15v c comp = 0.01 m f frequency (hz) 10 1 10 100 100 100k 1210 g09 1k 10k spot noise (nv/ ? hz or pa/ ? hz) e n ? n +i n bandwidth vs supply voltage bandwidth and feedback resistance vs capacitive load for peaking 1db bandwidth vs supply voltage
6 lt1210 supply current vs supply voltage 4 8 12 40 38 36 34 32 30 28 26 24 22 20 610 14 16 18 supply voltage ( v) supply current (ma) 1210 g10 t a = 25 c t a = 85 c t a = 125 c r sd = 0 w t a = 40 c supply current vs ambient temperature, v s = 5v temperature ( c) ?0 supply current (ma) 40 35 30 25 20 15 10 5 0 0 50 75 1210 g11 ?5 25 100 125 a v = 1 r l = r sd = 0 w r sd = 7.5k r sd = 15k supply current vs ambient temperature, v s = 15v temperature ( c) ?0 supply current (ma) 40 35 30 25 20 15 10 5 0 0 50 75 1210 g12 ?5 25 100 125 a v = 1 r l = r sd = 0 w r sd = 47.5k r sd = 82.5k supply current vs shutdown pin current shutdown pin current ( m a) 0 supply current (ma) 40 35 30 25 20 15 10 5 0 400 1210 g13 100 200 300 500 v s = 15v temperature ( c) ?0 v common mode range (v) 0.5 1.5 2.0 2.0 75 v + 1210 g14 1.0 0 125 1.5 1.0 0.5 50 ?5 100 25 input common mode limit vs junction temperature output short-circuit current vs junction temperature output saturation voltage vs junction temperature temperature ( c) ?0 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 25 75 1210 g15 ?5 0 50 100 125 output short-circuit current (a) sourcing sinking temperature ( c) ?0 output saturation voltage (v) 4 3 2 1 v 75 v + ? ? ? ? 1210 g16 0 125 50 25 100 25 v s = 15v r l = 2k r l = 10 w r l = 10 w r l = 2k power supply rejection ratio vs frequency frequency (hz) 20 power supply rejection (db) 40 60 70 10k 1m 10m 100m 1210 g17 0 100k 50 30 10 r l = 50 w v s = 15v r f = r g = 1k negative positive supply current vs large-signal output frequency (no load) frequency (hz) 10k supply current (ma) 100 90 80 70 60 50 40 30 20 100k 1m 10m 1210 g18 a v = 2 r l = v s = 15v v out = 20v p-p typical perfor a ce characteristics wu
7 lt1210 frequency (hz) output impedance ( w ) 100 10 1 0.1 0.01 100k 10m 100m 1210 g19 1m v s = 15v i o = 0ma r sd = 82.5k r sd = 0 w output impedance vs frequency frequency (hz) large-signal voltage gain (db) 18 15 12 9 6 3 0 10 3 10 5 10 7 1210 g21 10 4 10 6 10 8 a v = 4, r l = 10 w r f = 680 w , r g = 220 w v s = 15v, v in = 5v p-p large-signal voltage gain vs frequency frequency (mhz) 0 3rd order intercept (dbm) 2 468 1210 g22 10 56 54 52 50 48 46 44 42 40 v s = 15v r l = 10 w r f = 680 w r g = 220 w output impedance in shutdown vs frequency frequency (hz) output impedance ( w ) 10k 1k 100 10 1 100k 10m 100m 1210 g20 1m 3rd order intercept vs frequency test circuit for 3rd order intercept typical perfor a ce characteristics wu + 10 w lt1210 1210 tc01 220 w 680 w p o measure intercept at p o
8 lt1210 u s a o pp l ic at i wu u i for atio the lt1210 is a 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 less than 1db of peaking for various resistive loads and oper- ating 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 1db of peaking and a dashed line when the response has 1db 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 capacitive loads section). capacitive loads the lt1210 includes an optional compensation network for driving capacitive loads. this network eliminates most of the output stage peaking associated with capacitive loads, allowing the frequency response to be flattened. figure 1 shows the effect of the network on a 200pf load. without the optional compensation, there is a 6db 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 greatly reduces the peaking. a lower value feedback resistor can now be used, resulting in a response which is flat to 1db to 40mhz. the network has the greatest effect for c l in the range of 0pf to 1000pf. the graphs of bandwidth and feedback resistance vs capacitive load can be used to select the appropriate value of feedback resistor. the values shown are for 1db 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 capaci- frequency (mhz) 1 ? voltage gain (db) ? 2 6 10 10 100 1210 f01 ? 0 4 8 12 14 v s = 15v c l = 200pf r f = 1.5k compensation r f = 3.4k no compensation r f = 3.4k compensation figure 1 tance. also shown is the C 3db bandwidth with the sug- gested 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 10 w load, the bandwidth drops from 35mhz to 26mhz 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 pin must be connected to ground or v C . the shutdown pin can be used to either turn off the biasing for the amplifier, reducing the quiescent current to less than 200 m a, or to control the quiescent current in normal operation. the total bias current in the lt1210 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 part is shut down. in the shutdown mode, the output looks like a 70pf capacitor and the supply current is typically less than 100 m a. the shutdown pin is referenced to the posi- tive supply through an internal bias circuit (see the simpli- fied 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 lt1210. the switching time between the active and shut- down states is about 1 m s. a 24k pull-up resistor speeds
9 lt1210 u s a o pp l ic at i wu u i for atio figure 2. shutdown interface + lt1210 sd 15v 15v r f r g v in 5v 24k enable v out 1210 f02 15v 74c906 up the turn-off time and ensures that the lt1210 is completely turned off. because the pin is referenced to the positive supply, the logic used should have a break- down 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 3. shutdown operation a v = 1 r f = 825 w r l = 50 w r pull-up = 24k v in = 1v p-p v s = 15v v out enable 1210 f03 for applications where the full bandwidth of the amplifier is not required, the quiescent current of the device may be reduced by connecting a resistor from the shutdown pin to ground. the quiescent current will be approximately 65 times the current in the shutdown pin. the voltage across the resistor in this condition is v + C 3v be . for example, a 82k resistor will set the quiescent supply current to 9ma with v s = 15v. the photos in 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 9ma in the inverting configuration without much change in re- sponse. in noninverting mode, however, the slew rate is reduced as the quiescent current is reduced. 1210 f04a r f = 750 w r l = 10 w i q = 9ma, 18ma, 36ma v s = 15v figure 4b. large-signal response vs i q , a v = 2 r f = 750 w r l = 10 w figure 4a. large-signal response vs i q , a v = C1 1210 f04b i q = 9ma, 18ma, 36ma 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, 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
10 lt1210 u s a o pp l ic at i wu u i for atio when the lt1210 is used to drive capacitive loads, the available output current can limit the overall slew rate. in the fastest configuration, the lt1210 is capable of a slew rate of over 1v/ns. the current required to slew a capacitor 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 150v/ m s, determined by the current limit of 1.5a. the bandwidth is reduced. the photos in figures 5a, 5b and 5c show the large-signal response of the lt1210 for various gain configurations. the slew rate varies from 770v/ m s for a gain of 1, to 1100v/ m s for a gain of C 1. 1210 f05c r f = r g = 750 w r l = 10 w figure 5c. large-signal response, a v = 2 figure 5a. large-signal response, a v = 1 1210 f05a r f = 825 w r l = 10 w v s = 15v r f = r g = 750 w r l = 10 w v s = 15v 1210 f05b 1210 f06 r f = r g = 3k r l = v s = 15v 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. 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. figure 5b. large-signal response, a v = C1 figure 6. large-signal response, c l = 10,000pf v s = 15v
11 lt1210 u s a o pp l ic at i wu u i for atio power supplies the lt1210 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. power supply bypassing to obtain the maximum output and the minimum distor- tion from the lt1210, the power supply rails should be well bypassed. for example, with the output stage pouring 1a current peaks into the load, a 1 w power supply imped- ance will cause a droop of 1v, reducing the available output swing by that amount. surface mount tantalum and ceramic capacitors make excellent low esr bypass ele- ments when placed close to the chip. for frequencies above 100khz, use 1 m f and 100nf ceramic capacitors. if significant power must be delivered below 100khz, capacitive reactance becomes the limiting factor. larger ceramic or tantalum capacitors, such as 4.7 m f, are recom- mended in place of the 1 m f unit mentioned above. inadequate bypassing is evidenced by reduced output swing and distorted clipping effects when the output is driven to the rails. if this is observed, check the supply pins of the device for ripple directly related to the output waveform. significant supply modulation indicates poor bypassing. thermal considerations the lt1210 contains a thermal shutdown feature which protects against excessive internal (junction) tempera- ture. if the junction temperature of the device exceeds the protection threshold, the device will begin cycling be- tween 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 tem- perature until the device begins thermal shutdown gives a good indication of how much margin there is in the thermal design. copper area for surface mount devices 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 electri- cally 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 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. tables 1 and 2 list thermal resistance for each package. for the to-220 package, thermal resistance is given for junc- tion-to-case only since this package is usually mounted to a heat sink. measured values of thermal resistance for several different board sizes and copper areas are listed for each surface mount package. all measurements were taken in still air on 3/32" fr-4 board with 2 oz copper. this data can be used as a rough guideline in estimating thermal resistance. the thermal resistance for each appli- cation will be affected by thermal interactions with other components as well as board size and shape. table 1. r package, 7-lead dd thermal resistance topside* backside board area (junction-to-ambient) 2500 sq. mm 2500 sq. mm 2500 sq. mm 25 c/w 1000 sq. mm 2500 sq. mm 2500 sq. mm 27 c/w 125 sq. mm 2500 sq. mm 2500 sq. mm 35 c/w *tab of device attached to topside copper table 2. fused 16-lead so package thermal resistance topside backside board 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 copper area
12 lt1210 u s a o pp l ic at i wu u i for atio then: t j = (0.56w)(46 c/w) + 70 c = 96 c for the so package with 1000 sq. mm topside heat sinking t j = (0.56w)(27 c/w) + 70 c = 85 c for the r package with 1000 sq. mm topside heat sinking since the maximum junction temperature is 150 c, both packages are clearly acceptable. + lt1210 sd ?5v 15v 24k 10k 5v 2n3904 1210 ta04 cmos logic to shutdown interface precision 10 high current amplifier + lt1097 + lt1210 v in sd comp 0.01 m f 3k 330 w 9.09k 1k out output offset: < 500 m v slew rate: 2v/ m s bandwidth: 4mhz stable with c l < 10nf 1210 ta03 500pf typical applicatio n s u t7 package, 7-lead to-220 thermal resistance (junction-to-case) = 5 c/w calculating junction temperature the junction temperature can be calculated from the equation: t j = (p d )( q ja ) + t a 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 7 for the so and r packages 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. p d = (76ma)(10v) C (1.4v) 2 / 10 = 0.56w + lt1210 sd 5v ?v 680 w 220 w 10 w 0v 2v v o v o = 1.4v rms 76ma 1210 f07 ?v a figure 7
13 lt1210 typical applicatio n s u distribution amplifier buffer a v = 1 + lt1210 sd 75 w v in r f r g 75 w 75 w 75 w 75 w 75 w cable 1210 ta05 + lt1210 sd 0.01 m f* v out r f ** v in 1210 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 si plified sche atic w w 1210 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
14 lt1210 package descriptio n u dimensions in inches (millimeters) unless otherwise noted. r package 7-lead plastic dd pak (ltc dwg # 05-08-1462) s package 16-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) 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 * ** r (dd7) 0396 0.026 ?0.036 (0.660 ?0.914) 0.143 +0.012 0.020 () 3.632 +0.305 0.508 0.040 ?0.060 (1.016 ?1.524) 0.013 ?0.023 (0.330 ?0.584) 0.095 ?0.115 (2.413 ?2.921) 0.004 +0.008 0.004 () 0.102 +0.203 0.102 0.050 0.012 (1.270 0.305) 0.059 (1.499) typ 0.045 ?0.055 (1.143 ?1.397) 0.165 ?0.180 (4.191 ?4.572) 0.330 ?0.370 (8.382 ?9.398) 0.060 (1.524) typ 0.390 ?0.415 (9.906 ?10.541) 15 typ 0.300 (7.620) 0.075 (1.905) 0.183 (4.648) 0.060 (1.524) 0.060 (1.524) 0.256 (6.502) bottom view of dd pak hatched area is solder plated copper heat sink
15 lt1210 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 its circuits as described herein will not infringe on existing patent rights. package descriptio n u dimensions in inches (millimeters) unless otherwise noted. 0.040 ?0.060 (1.016 ?1.524) 0.026 ?0.036 (0.660 ?0.914) t7 (to-220) (formed) 0695 0.135 ?0.165 (3.429 ?4.191) 0.700 ?0.728 (17.780 ?18.491) 0.045 ?0.055 (1.143 ?1.397) 0.165 ?0.180 (4.293 ?4.572) 0.095 ?0.115 (2.413 ?2.921) 0.013 ?0.023 (0.330 ?0.584) 0.620 (15.75) typ 0.155 ?0.195 (3.937 ?4.953) 0.152 ?0.202 (3.860 ?5.130) 0.260 ?0.320 (6.604 ?8.128) 0.147 ?0.155 (3.734 ?3.937) dia 0.390 ?0.415 (9.906 ?10.541) 0.330 ?0.370 (8.382 ?9.398) 0.460 ?0.500 (11.684 ?12.700) 0.570 ?0.620 (14.478 ?15.748) 0.230 ?0.270 (5.842 ?6.858) t7 package 7-lead plastic to-220 (standard) (ltc dwg # 05-08-1422)
16 lt1210 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 0796 7k ? printed in usa typical applicatio n u related parts part number description comments lt1010 fast 150ma power buffer 20mhz bandwidth, 75v/ m s slew rate lt1166 power output stage automatic bias system sets class ab bias currents for high voltage/high power output stages lt1206 single 250ma, 60mhz current feedback amplifier shutdown function, stable with c l = 10,000pf, 900v/ m s slew rate lt1207 dual 250ma, 60mhz current feedback amplifier dual version of lt1206 lt1227 single 140mhz current feedback amplifier shutdown function, 1100v/ m s slew rate lt1360 single 50mhz, 800v/ m s op amp voltage feedback, stable with c l = 10,000pf lt1363 single 70mhz, 1000v/ m s op amp voltage feedback, stable with c l = 10,000pf wideband 9w bridge amplifier + lt1210 sd 10nf 1 1 1 1 1 t1* 1 r l 50 w 9w p o 9w 680 w 220 w 100nf 910 w * coiltronics versa-pac tm ctx-01-13033-x2 or equivalent 15v 15v 15v 15v input 5v p-p 1210 ta07 + lt1210 sd 10nf frequency (hz) gain (db) 26 23 20 17 14 11 8 5 2 ? ? 10k 1m 10m 100m 1210 ta08 100k frequency response versa-pac is a trademark of coiltronics, inc.

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