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1 typical application features description precision , gain selectable high side current sense amplifier the lt ? 6100 is a complete micropower, precision, high side current sense amplifier. the LT6100 monitors unidi- rectional currents via the voltage across an external sense resistor. fixed gains of 10, 12.5, 20, 25, 40, 50v/v are obtained by simply strapping or floating two gain select pins. gain accuracy is better than 0.5% for all gains. the LT6100 sense inputs have a voltage range that extends from 4.1v to 48v, and can withstand a differential voltage of the full supply. this makes it possible to monitor the voltage across a mosfet switch or a fuse. the part can also withstand a reverse battery condition on the inputs. input offset is a low 300v. cmrr and psrr are in ex- cess of 105db, resulting in a wide dynamic range . a filter pin is provided to easily implement signal filtering with a single capacitor. the LT6100 has a separate supply input, which operates from 2.7v to 36v and draws only 60a. when v cc is powered down, the sense pins are biased off. this pre- vents loading of the monitored circuit , irrespective of the sense voltage. the LT6100 is available in an 8-lead dfn and msop package. 0a to 33a high side current monitor with 12khz frequency rolloff applications n input offset voltage: 300v (max) n sense inputs up to 48v n 0.5% gain accuracy n pin selectable gain: 10, 12.5, 20, 25, 40, 50v/v n separate power supply: 2.7v to 36v n operating current: 60a n sense input current (v cc powered down): 1na n reverse battery protected to C48v n buffered output n noise filtering input n C40 c to 125c operating temperature range n available in 8-lead dfn and msop packages n battery monitoring n fuse monitoring n portable and cellular phones n portable test/measurement systems v ee v out 4 fil a4 v cc v s + r sense 3m 8 v s ? 1 3v configured for gain = 25v/v 4.4v to 48v supply a2 7 2 6 LT6100 3 5 6100 ta01a v out = 2.5v i sense = 33a 220pf load v s sense input voltage (v) ?1.5 input offset voltage (mv) ?0.5 0.5 1.5 ?1.0 0 1.0 10 20 30 40 6100 ta01b 50 50 15 25 35 45 v sense = 100mv v cc = 3v t a = 25c input offset voltage vs v s sense input voltage l, lt , lt c , lt m , linear technology, the linear logo and over-the- top are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. LT6100 6100fd for more information www.linear.com/LT6100
2 absolute maximum ratings differential sense voltage ...................................... 48 v total v s + , v s C to v ee ............................................... 48 v total v cc supply voltage from v ee ......................... 36 v output voltage ............................... ( v ee ) to ( v ee + 36 v ) output short - circuit duration ( note 3) ........ continuous operating temperature range ( note 4) lt 6100 c ............................................ C40 c to 85 c lt 6100 i .............................................. C40 c to 85 c lt 6100 h .......................................... C40 c to 125 c (notes 1, 2) package/ order information top view 9 dd package 8-lead (3mm 3mm) plastic dfn 5 6 7 8 4 3 2 1v s ? v cc fil v ee v s + a4 a2 v out t jmax = 125c, ja = 43c/w exposed pad (pin 9) is v ee , must be soldered to pcb 1 2 3 4 v s ? v cc fil v ee 8 7 6 5 v s + a4 a2 v out top view ms8 package 8-lead plastic msop t jmax = 150c, ja = 250c/w specified temperature range ( note 5) lt 6100 c ................................................ 0 c to 70 c lt 6100 i .............................................. C40 c to 85 c lt 6100 h .......................................... C40 c to 125 c storage temperature range ........................................... dfn .................................................... C65 c to 125 c msop ................................................ C65 c to 150 c lead temperature ( soldering , 10 sec ) msop .............................................................. 300 c order information lead free finish tape and reel part marking* package description specified temperature range LT6100cdd#pbf LT6100cdd#trpbf lbmw 8-lead (3mm 3mm) plastic dfn 0c to 70c LT6100idd#pbf LT6100idd#trpbf lbmw 8-lead (3mm 3mm) plastic dfn C40c to 85c LT6100hdd#pbf LT6100hdd#trpbf lbmw 8-lead (3mm 3mm) plastic dfn C40c to 125c LT6100cms8#pbf LT6100cms8#trpbf ltbmv 8-lead plastic ms8 0c to 70c lt 6100ims8#pbf LT6100ims8#trpbf ltbmv 8-lead plastic ms8 C40c to 85c LT6100hms8#pbf LT6100hms8#trpbf ltbmv 8-lead plastic ms8 C40c to 125c consult lt c marketing for parts specified with wider operating temperature ranges. *the temperature grade is identified by a label on the shipping container. consult lt c marketing for information on nonstandard 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/ LT6100 6100fd for more information www.linear.com/LT6100
3 electrical characteristics the l denotes specifications which apply over the temperature range 0c t a 70c (LT6100c), otherwise specifications are t a = 25c. v cc = 5v, v ee = 0v, v s + = v cc + 1.4v unless otherwise specified. (note 5) symbol parameter conditions min typ max units v s C , v s + sense amplifier supply voltage v cc = 2.7v l 4.1 48 v v sense input sense voltage full scale v sense = v s + C v s C , v cc = 3v, a v = 10v/v v sense = v s + C v s C , v cc = 5v, a v = 10v/v l l 110 300 mv mv v os input offset voltage (ms package) i out = 0 l C300 C500 80 300 500 v v input offset voltage (dd package) i out = 0 l C350 C550 80 350 550 v v v os tc temperature coefficient of v os (note 6) l 0.5 3 v/c a v gain, v out /v sense v sense = 50mv to 80mv, a v = 10v/v LT6100ms8 LT6100dd8 l 9.95 9.94 9.90 10.05 10.06 10.10 v/v v/v v/v v s = 48v, v sense = 50mv to 80mv, a v = 10v/v l 9.90 10.10 v/v output voltage gain error ( note 7) v sense = 50mv to 80mv, a v = 10, 12.5, 20, 25, 40, 50v/v LT6100ms8 LT6100dd8 l C0.5 C0.6 C1.0 0.5 0.6 1.0 % % % v s = 48v, v sense = 50mv to 80mv, a v = 10, 12.5, 20, 25, 40, 50v/v l C1.0 1.0 % v s cmrr v s sense input common mode rejection ratio v sense = 50mv, v cc = 2.7v, v s = 4.1v to 36v l 105 100 120 120 db db v cc psrr v cc supply rejection ratio v sense = 50mv, v s = 36v, v cc = 3v to 30v l 105 100 120 120 db db v cc supply voltage v cc l 2.7 36 v bw bandwidth a v = 10v/v, f o = C3db, v cc = 15v a v = 50v/v, f o = C3db, v cc = 15v 100 20 150 50 khz khz t s output settling to 1% final value v sense = 10mv to 100mv 15 s i s + (o) , i s C (o) sense input current v sense = 0v l 4.5 10 a i cc(o) v cc supply current v sense = 0v l 60 130 a sr slew rate (note 8) v cc = 15v, v sense = 26mv to 380mv, a v = 50v/v l 0.03 0.02 0.05 0.05 v/s v/s i sc short- circuit current i sc + , i sc C 8 15 ma reverse v s supply i s( total) = C200a, v cc = open l 50 60 v v o(min) minimum output voltage v sense = 0v, no load v sense = v s + C v s C = C100mv, a v = 50v/v, no load l 15 15 30 25 mv mv v o(max) output high (referred to v cc ) a v = 50v/v, v sense = 100mv, i l = 0 v sense = 100mv, i l = 100a v sense = 100mv, i l = 500a v sense = 100mv, i l = 1ma l l l l 75 85 125 175 125 150 250 400 mv mv mv mv i s + , i s C (off) sense input current (power down) v cc = 0v, v s = 48v, v sense = 0v l 0.001 1 a LT6100 6100fd for more information www.linear.com/LT6100
4 electrical characteristics the l denotes specifications which apply over the temperature range C40c t a 85c (LT6100i), otherwise specifications are t a = 25c. v cc = 5v, v ee = 0v, v s + = v cc + 1.4v unless otherwise specified. (note 5) symbol parameter conditions min typ max units v s C , v s + sense amplifier supply voltage v cc = 2.7v l 4.1 48 v v sense input sense voltage full scale v sense = v s + C v s C , v cc = 3v, a v = 10v/v v sense = v s + C v s C , v cc = 5v, a v = 10v/v l l 110 300 mv mv v os input offset voltage (ms package) i out = 0 l C300 C550 80 300 550 v v input offset voltage (dd package) i out = 0 l C350 C600 80 350 600 v v v os tc temperature coefficient of v os (note 6) l 0.5 3 v/c a v gain, v out /v sense v sense = 50mv to 80mv, a v = 10v/v LT6100ms8 LT6100dd8 l 9.95 9.94 9.90 10.05 10.06 10.10 v/v v/v v/v v s = 48v, v sense = 50mv to 80mv, a v = 10v/v l 9.90 10.10 v/v output voltage gain error ( note 7) v sense = 50mv to 80mv, a v = 10, 12.5, 20, 25, 40, 50v/v LT6100ms8 LT6100dd8 l C0.5 C0.6 C1.0 0.5 0.6 1.0 % % % v s = 48v, v sense = 50mv to 80mv, a v = 10, 12.5, 20, 25, 40, 50v/v l C1.0 1.0 % v s cmrr v s sense input common mode rejection ratio v sense = 50mv, v cc = 2.7v, v s = 4.1v to 36v l 105 100 120 120 db db v cc psrr v cc supply rejection ratio v sense = 50mv, v s = 36v, v cc = 3v to 30v l 105 100 120 120 db db v cc supply voltage v cc l 2.7 36 v bw bandwidth a v = 10v/v, f o = C3db, v cc = 15v a v = 50v/v, f o = C3db, v cc = 15v 100 20 150 50 khz khz t s output settling to 1% final value v sense = 10mv to 100mv 15 s i s + (o) , i s C (o) sense input current v sense = 0v l 4.5 10 a i cc(o) supply current v sense = 0v l 60 145 a sr slew rate (note 8) v cc = 15v, v sense = 26mv to 380mv, a v = 50v/v l 0.03 0.02 0.05 0.05 v/s v/s i sc short- circuit current i sc + , i sc C 8 15 ma reverse v s supply i s( total) = C200a, v cc = open l 50 60 v v o(min) minimum output voltage v sense = 0v, no load v sense = v s + C v s C = C100mv, a v = 50v/v, no load l 15 15 30 25 mv mv v o(max) output high (referred to v cc ) a v = 50v/v, v sense = 100mv, i l = 0 v sense = 100mv, i l = 100a v sense = 100mv, i l = 500a v sense = 100mv, i l = 1ma l l l l 75 85 125 175 125 150 250 400 mv mv mv mv i s + , i s C (off) sense input current (power down) v cc = 0v, v s = 48v, v sense = 0v l 0.001 1 a LT6100 6100fd for more information www.linear.com/LT6100
5 electrical characteristics the l denotes specifications which apply over the temperature range C40c t a 125c (LT6100h), otherwise specifications are t a = 25c. v cc = 5v, v ee = 0v, v s + = v cc + 1.4v unless otherwise specified. (note 5) symbol parameter conditions min typ max units v s C , v s + sense amplifier supply voltage v cc = 2.7v l 4.1 48 v v sense input sense voltage full scale v sense = v s + C v s C , v cc = 3v, a v = 10v/v v sense = v s + C v s C , v cc = 5v, av = 10v/v l l 110 300 mv mv v os input offset voltage (ms package) i out = 0 l C300 C600 80 300 600 v v input offset voltage (dd package) i out = 0 l C350 C650 80 350 650 v v v os tc temperature coefficient of v os (note 6) l 0.5 5 v/c a v gain, v out /v sense v sense = 50mv to 80mv, a v = 10v/v LT6100ms8 LT6100dd8 l 9.95 9.94 9.90 10.05 10.06 10.10 v/v v/v v/v v s = 48v, v sense = 50mv to 80mv, a v = 10v/v l 9.90 10.10 v/v output voltage gain error (note 7) v sense = 50mv to 80mv, av = 10, 12.5, 20, 25, 40, 50v/v LT6100ms8 LT6100dd8 l C0.5 C0.6 C1.0 0.5 0.6 1.0 % % % v s = 48v, v sense = 50mv to 80mv, a v = 10, 12.5, 20, 25, 40, 50v/v l C1.0 1.0 % v s cmrr v s sense input common mode rejection ratio v sense = 50mv, v cc = 2.7v, v s = 4.1v to 36v l 105 100 120 120 db db v cc psrr v cc supply rejection ratio v sense = 50mv, v s = 36v, v cc = 3v to 30v l 105 95 120 120 db db v cc supply voltage v cc l 2.7 36 v bw bandwidth a v = 10v/v, f o = C3db, v cc = 15v a v = 50v/v, f o = C3db, v cc = 15v 100 20 150 50 khz khz t s output settling to 1% final value v sense = 10mv to 100mv 15 s i s + (o) , i s C (o ) sense input current v sense = 0v l 4.5 10 a i cc(o) supply current v sense = 0v l 60 170 a sr slew rate (note 8) v cc = 15v, v sense = 26mv to 380mv, a v = 50v/v l 0.03 0.02 0.05 0.05 v/s v/s i sc short- circuit current i sc + , i sc C 8 15 ma reverse v s supply i s( total) = C200a, v cc = open l 50 60 v v o(min) minimum output voltage v sense = 0v, no load v sense = v s + C v s C = C100mv, a v = 50v/v, no load l 15 15 35 25 mv mv v o(max) output high (referred to v cc ) a v = 50v/v, v sense = 100mv, i l = 0 v sense = 100mv, i l = 100a v sense = 100mv, i l = 500a v sense = 100mv, i l = 1ma l l l l 75 85 125 175 140 160 250 400 mv mv mv mv i s + , i s C (off) sense input current (power down) v cc = 0v, v s = 48v, v sense = 0v l 0.001 1 a LT6100 6100fd for more information www.linear.com/LT6100
6 typical performance characteristics output voltage vs sense voltage output voltage vs sense voltage gain vs temperature input offset voltage vs temperature input offset voltage vs v s + input voltage input offset voltage vs v cc supply voltage temperature (c) ?40 input offset voltage (v) 400 300 200 100 0 ?100 ?200 ?300 ? 400 80 6100 g21 ?10 20 50 125 65 ?25 5 35 11095 9 typical units v s = 6.4v v cc = 5v v s + input voltage (v) 0 ?3.5 input offset voltage (mv) ?3.0 ?2.0 ?1.5 ?1.0 1.5 0 20 40 50 6100 g01 ?2.5 0.5 1.0 ?0.5 10 30 t a = ?40c v sense = 100mv v cc = 3v t a = 125c t a = 25c t a = 85c v cc supply voltage (v) 0 input offset voltage (v) 200 250 300 30 6100 g02 150 100 10 20 5 35 15 25 40 50 0 350 v sense = 100mv v s + = 48v t a = ?40c t a = 125c t a = 25c t a = 85c sense voltage (v s + ? v s ? )(mv) ?150 0 output voltage (v) 0.2 0.6 0.8 1.0 30 90 1.8 6100 g03 0.4 ?90 ?30 150 1.2 1.4 1.6 v s + = 4.4v to 48v v cc = 3v a v = 10v/v t a = ?40c to 125c t a = ?40c v s = 4.4v t a = ?40c v s > 4.6v sense voltage (v s + ? v s ? ) (mv) 0 0 output voltage (v) 0.5 1.5 2.0 2.5 3.5 6100 g04 1.0 3.0 120 300 60 180 240 v s + = 6.4v to 48v v cc = 5v t a = ?40c to 125c t a = ?40c v s = 6.4v t a = ?40c v s > 6.6v temperature (c) ?40 gain (v/v) 49.98 49.96 49.94 49.92 49.90 49.88 50 65 80 11095 50.06 6100 g05 ?25 ?10 5 20 35 125 50.00 50.02 50.04 7 typical units v sense = 50mv to 80mv v s + = 6.4v to 48v v cc = 5v a v = 50v/v electrical characteristics 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: esd (electrostatic discharge) sensitive devices. extensive use of esd protection devices are used internal to the LT6100, however, high electrostatic discharge can damage or degrade the device. use proper esd handling precautions . note 3: a heat sink may be required to keep the junction temperature below absolute maximum ratings. note 4: the LT6100c/LT6100i are guaranteed functional over the operating temperature range of C40c to 85c. the LT6100h is guaranteed functional over the operating temperature range of C40c to 125c. note 5: the LT6100c is guaranteed to meet specified performance from 0c to 70c. the lt 6100c is designed, characterized and expected to meet specified performance from C40c to 85c but is not tested or a sampled at these temperatures. the LT6100i is guaranteed to meet specified performance from C40c to 85c. the LT6100h is guaranteed to meet specified performance from C40c to 125c. note 6: this parameter is not 100% tested. note 7: gain error for a v = 12.5, 25v/v is guaranteed by the other gain error tests. note 8: slew rate is measured on the output between 3.5v and 13.5v. LT6100 6100fd for more information www.linear.com/LT6100
7 negative sense input current vs sense voltage positive sense input current vs sense voltage output positive swing vs load current typical performance characteristics cmrr vs frequency v cc psrr vs frequency gain error vs v sense v cc supply current vs v s input voltage op amp output impedance vs frequency gain vs frequency sense voltage (v s + ? v s ? ) (mv) ?110 negative sense input current (a) 8 10 12 110 6100 g06 6 4 0 ?70 ?30 30 70 2 v s + = 4.4v to 48v v cc = 3v t a = 125c t a = ?40c t a = 85c t a = 25c sense voltage (v s + ? v s ? ) (mv) ?110 positive sense input current (a) 20 25 30 110 6100 g07 10 ?5 ?70 ?30 30 70 35 15 5 0 v s + = 4.4v to 48v v cc = 3v t a = 125c t a = ?40c t a = 85c t a = 25c load current (ma) 0 0 output positive swing (mv) 50 150 200 250 350 0.1 0.5 0.7 6100 g08 100 300 0.4 0.9 1.0 0.2 0.3 0.6 0.8 v s + = 6.4v v cc = 5v v sense = 150mv a v = 50v/v t a = 125c t a = ?40c t a = 25c t a = 85c total v s input voltage (v) 0 v cc supply current (a) 120 160 200 40 6100 g09 80 40 100 140 180 60 20 0 10 20 30 50 v sense = 0v v cc = 3v t a = 125c t a = ?40c t a = 25c t a = 85c frequency (hz) 1k 0.1 output impedance () 100 1k 10k 10k 100k 1m 6100 g23 10 1 g2 = 5v/v g2 = 1v/v g2 = 2v/v v s + , v s ? = 6.5v v cc = 5v v ee = ?5v fil = 0v frequency (hz) 100 ?10 gain (db) 0 10 20 30 1k 10k 100k 1m 10m 6100 g10 ?20 ?30 ?40 ?50 40 50 a v = 50 a v = 10 v s = 12.1v v cc = 10v frequency (hz) 10 40 cmrr (db) 60 80 100 1k 10k 100k 1m 6100 g11 20 0 100 120 140 v s = 6.4v v cc = 5v frequency (hz) 10.1 10 v cc psrr (db) 100 1k 10k 100k 1m 6100 g12 10 ?10 50 30 70 90 110 130 150 v s = 10v v sense = 100mv v cc = 5v v sense (mv) 0 ?3 gain error (%) ?2 ?1 0 1 50 100 150 200 6100 g24 250 300 v s + = 6.4v v cc = 5v a v = 10v/v t a = 25c LT6100 6100fd for more information www.linear.com/LT6100
8 typical performance characteristics step response at v sense = 0v to 10mv step response at v sense = 0v to 10mv step response at v sense = 0v to 130mv 10v v ? 20mv/div v out 50mv/div 0v 50s/div v s + = 10v a v = 10v/v c out = 0pf 6100 g15 10v v ? 20mv/div v out 200mv/div 0v 50s/div v s + = 10v a v = 50v/v c l = 0pf 6100 g16 10v 0v 50s/div v s + = 10v a v = 10v/v c out = 1000pf 6100 g17 v ? 50mv/div v out 500mv/div step response at v sense = 0v to 130mv step response at v sense = 0v to 10mv 10v 0v 0.2ms/div v s + = 10v a v = 50v/v c l = 1000pf 6100 g18 v? 100mv/div v out 2v/div 10v 0v 50s/div v s + = 10v a v = 10v/v c l = 1000pf 6100 g19 v? 20mv/div v out 50mv/div sense input current (v cc powered down) vs v s + step response at v sense = 0v to 130mv step response at v sense = 0v to 130mv v s + (v) 0.01 total input current (i s + + i s ? ) (na) 0.1 1 10 0 20 30 40 0.001 10 50 6100 g25 t a = 125c v s + = v s ? t a = 85c t a = 25c t a = ?40c 10v v ? 50mv/div v out 500mv/div 0v 50s/div v s + = 10v a v = 10v/v c l = 0pf 6100 g13 10v v ? 100mv/div v out 2v/div 0v 0.2ms/div v s + = 10v a v = 50v/v c l = 0pf 6100 g14 LT6100 6100fd for more information www.linear.com/LT6100
9 pin functions typical performance characteristics step response at v sense = 0v to 10mv start-up delay 10v 0v 50s/div v s + = 10v a v = 50v/v c l = 1000pf 6100 g20 v? 20mv/div v out 200mv/div 10v 0v 0v 1v 20s/div v cc = 5v v sense = 100mv a v = 10v/v v ee = 0v 6100 g22 v s + v out v s C (pin 1): negative sense input terminal . negative sense voltage input will remain functional for voltages up to 48v. v s C is connected to an internal gain-setting resistor r g1 = 5k. v cc (pin 2): supply voltage input. this power supply pin supplies current to both current sense amplifier and op amp. fil (pin 3): filter pin. connects to an external capacitor to roll off differential noise of the system. pole frequency f C3db = 1/(2r fil c), r fil = r e + r o = 60k. v ee (pin 4): negative supply or ground for single supply operation. v out ( pin 5): voltage output proportional to the magnitude of the current flowing through r sense : v out = a v ? (v sense v os ) v os is the input offset voltage. a v is the total gain of the LT6100. a2 (pin 6): gain select pin. refer to table 1. a4 (pin 7): gain select pin. when pin 7 is shorted to v ee , the total gain is 40v/v. when both pin 6 and pin 7 are shorted to v ee , the total gain is 50v/v. when both pin 6 and pin 7 are opened, the total gain is 10v/v. v s + (pin 8): positive sense input terminal . connecting a supply to v s + and a load to v s C will allow the LT6100 to monitor the current through r sense , refer to figure 1. v s + is connected to an internal gain setting resistor r g2 = 5 k. v s + remains functional for voltages up to 48v. LT6100 6100fd for more information www.linear.com/LT6100
10 functional diagram ? + ? + 8 7 5 1 v s ? load r g1 5k v cc 2.7v to 36v r g2 5k v in (v cc + 1.4v) to 48v r r o 50k r/3 a4 6 a2 3 fil 4 v ee v s + r sense v out 6100 f01 a1 a2 q1 v o1 r e 10k r 25k 2 figure 1. functional diagram LT6100 6100fd for more information www.linear.com/LT6100
11 the LT6100 high side current sense amplifier (figure 1) provides accurate unidirectional monitoring of current through a user-selected sense resistor. the LT6100 fea- tures a fully specified 4.1v to 48v input common mode range. a high psrr v cc supply (2.7v to 36v) powers the current sense amplifier and the internal op amp circuitry . the input sense voltage is level shifted from the positive sense power supply to the ground reference and amplified by a user-selected gain to the output. the buffered output voltage is directly proportional to the current flowing through the sense resistor. theory of operation (refer to figure 1) current from the source at v s + flows through r sense to the load at v s C , creating a sense voltage, v sense . inputs v s + and v s C apply the sense voltage to r g2 . the opposite ends of resistors r g1 and r g2 are forced to be at equal potentials by the voltage gain of amplifier a1. the current through r g2 is forced to flow through transistor q1 and is sourced to node v o 1 . the current from r g 2 flowing through resistor r o gives a voltage gain of ten, v o1 /v sense = r o / r g2 = 10 v/v. the sense amplifier output at v o1 is ampli- fied again by amplifier a2. the inputs of amplifier a2 can operate to ground which ensures that small sense voltage signals are detected. amplifier a2 can be programmed to different gains via pin 6 and pin 7. thus, the total gain of the system becomes a v = 10 ? a2 and v out = v sense ? a v . gain setting the LT6100 gain is set by strapping (or floating) the two gain pins (see table 1). this feature allows the user to zoom in by increasing the gain for accurate measure- ment of low currents. a v = 10v/v ? g2, g2 is the gain of op amp a2. table 1. gain set with pin 6 and pin 7 a2 (pin 6) a4 (pin 7) g2 a v open open 1 10 v ee out 1.25 12.5 v ee open 2 20 out v ee 2.5 25 open v ee 4 40 v ee v ee 5 50 selection of external current sense resistor external r sense resistor selection is a delicate trade-off between power dissipation in the resistor and current mea- surement accuracy. the maximum sense voltage may be as large as 300mv to get maximum dynamic range. for high current applications, the user may want to minimize the sense voltage to minimize the power dissipation in the sense resistor. the LT6100s low input offset voltage of 80v allows for high resolution of low sense voltages. this allows limiting the maximum sense voltage while still providing high resolution current monitoring. kelvin connection of the LT6100s v s + and v s C inputs to the sense resistor should be used to provide the highest accuracy in high current applications. solder connections and pc board interconnect resistance ( approximately 0.5m per square) can be a large error in high current systems. a 5a application might choose a 20m sense resistor to give a 100mv full-scale input to the LT6100. input offset voltage will limit resolution to 4ma. neglect- ing contact resistance at solder joints, even one square of pc board copper at each resistor end will cause an error of 5%. this error will grow proportionately higher as monitored current levels rise. applications information LT6100 6100fd for more information www.linear.com/LT6100
12 applications information noise filtering the LT6100 provides signal filtering via pin fil that is internally connected to the resistors r e and r o . this pin may be used to filter the input signal entering the LT6100s internal op amp, and should be used when fast ripple cur - rent or transients flow through the sense resistor. high frequency signals above the 300khz bandwidth of the LT6100s internal amplifier will cause errors. a capacitor connected between fil and v ee creates a single pole low pass filter with corner frequency: f C3db = 1/(2r fil c) where r fil = 60 k. a 220pf capacitor creates a pole at 12khz, a good choice for many applications. output signal range the LT6100 s output signal is developed by current through r g 2 into output resistor r o . the current is v sense / r g 2 . the sense amplifier output, v o1 , is buffered by the internal op amp so that connecting the output pins to other systems will preserve signal accuracy. for zero v sense , internal circuit saturation with loss of accuracy occurs at the minimum v out swing, 15mv above v ee . v out may swing positive to within 75mv of v cc or a maximum of 36v, a limit set by internal junction breakdown. within these constraints, an amplified, level shifted representation of the r sense voltage is developed at v out . the output is well behaved driving capacitive loads to 1000pf. sense input signal range the LT6100 has high cmrr over the wide input voltage range of 4.1v to 48v. the minimum operation voltage of the sense amplifier input is 1.4v above v cc . the output remains accurate even when the sense inputs are driven to 48v. figure 2 shows that v os changes very slightly over a wide input range. furthermore, the sense inputs v s + and v s C can collapse to zero volts without incurring any damage to the device. the LT6100 can handle dif- ferential sense voltages up to the voltage of the sense inputs supplies. for example, v s + = 48 v and v s C = 0 v can be a valid condition in a current monitoring application (figure 3) when an overload protection fuse is blown and v s C voltage collapses to ground. under this condition, the output of the LT6100 goes to the positive rail, v oh . there is no phase inversion to cause an erroneous output signal. for the opposite case when v s + collapse to ground with v s C held up at some higher voltage potential, the output will sit at v ol . if both inputs fall below the minimum cm voltage, v cc + 1.4v, the output is indeterminate but the LT6100 will not be damaged. v s input voltage (v) 0 ?3.5 input offset voltage (mv) ?3.0 ?2.0 ?1.5 ?1.0 1.5 0 20 40 50 6100 f02 ?2.5 0.5 1.0 ?0.5 10 30 v sense = 100mv v cc = 3v t a = 25c output v ee out 6100 f03 r sense fuse LT6100 81 v s ? v s + a4 2 v cc a2 3 4 7 c2 0.1f c1 0.1f dc source 5v 6 5 fil to load ? + + figure 2. v os vs v s input voltage figure 3. current monitoring of a fuse protected circuit LT6100 6100fd for more information www.linear.com/LT6100
13 applications information low sense voltage operation figure 4 shows the simplest circuit configuration in which the LT6100 may be used. while v out (output voltage) increases with positive sense current, at v sense = 0 v, the LT6100s buffered output can only swing as low as v ol = 15mv. the accuracy at small sense voltages can be improved by selecting higher gain. when gain of 50v/v is selected, as shown in figure 7, v out leaves the clipped region for a positive v sense greater than 1mv compared to 2.5mv for gain of 10v/v (see figure 6). output v ee out 6100 f04 r sense LT6100 81 v s ? v s + a4 2 v cc a2 3 4 7 c2 0.1f c1 0.1f 3v 6 5 fil to load + 5v + ? + sense voltage (v s + ? v s ? ) (mv) 0 output voltage (v) 0.6 0.8 1.0 90 150 6100 f05 0.4 0.2 0 30 60 120 1.2 1.4 1.6 v s = 4.4v to 48v v cc = 3v a v = 10v/v t a = 25c figure 4. LT6100 load current monitor figure 5. output voltage vs v sense sense voltage (v s + ? v s ? ) (mv) 0 output voltage (v) 0.15 0.20 0.25 15 25 6100 f06 0.10 0.05 0 5 10 20 0.30 0.35 0.40 30 v s = 4.4v to 48v v cc = 3v a v = 10v/v t a = 25c sense voltage (v s + ? v s ? ) (mv) 0 0 output voltage (v) 0.2 0.6 0.8 1.0 20 1.8 6100 f07 0.4 10 5 25 15 30 1.2 1.4 1.6 v s = 4.4v to 48v v cc = 3v a v = 50v/v t a = 25c figure 6. expanded view of output voltage vs v sense , a v = 10v/v figure 7. expanded view of output voltage vs v sense , a v = 50v/v LT6100 6100fd for more information www.linear.com/LT6100
14 applications information power down while connected to a battery another unique benefit of the lt 6100 is that you can leave it connected to a battery even when it is denied power. when the LT6100 loses power or is intentionally powered down, its inputs remain high impedance (see figure 8). this is due to the implementation of linear technology s over- the- top ? input topology at its front end . when powered down, the LT6100 inputs draw less than 1a of current. v out fil v cc power down ok inputs remain hi-z v cc 0v 3v 6100 f08 r sense LT6100 v s ? v s + v ee a2 a4 to load i sense ? + battery 4.1v to 48v + figure 8. input remains hi-z when LT6100 is powered down typical application adjust gain dynamically for enhanced range v out fil v cc 0v (gain = 10) 5v (gain = 50) 6100 ta05 r sense LT6100 v s ? v s + v ee 2n7002 a2 a4 to load 5v i sense from source ? + micro -hotplate voltage and current monitor micro-hotplate boston microsystems mhp100s-005 i hotplate m9 lt1991 5v 6100 ta06 5v m3 m1 p1 p3 p9 10 1% + ? v s ? v ee v cc a2 LT6100 5v current monitor v out = 500mv/ma voltage monitor v out = www.bostonmicrosystems.com v dr + v dr ? a4 v s + v dr + ? v dr ? 10 LT6100 6100fd for more information www.linear.com/LT6100
15 package description package description please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-1) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on top and bottom of package 0.40 0.10 bottom view?exposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.125 typ 2.38 0.10 1 4 8 5 pin 1 top mark (note 6) 0.200 ref 0.00 ? 0.05 (dd8) dfn 0509 rev c 0.25 0.05 2.38 0.05 recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 1.65 0.05 (2 sides) 2.10 0.05 0.50 bsc 0.70 0.05 3.5 0.05 package outline 0.25 0.05 0.50 bsc dd package 8-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1698 rev c) LT6100 6100fd for more information www.linear.com/LT6100
16 package description package description please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. msop (ms8) 0213 rev g 0.53 0.152 (.021 .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 0.0508 (.004 .002) 0.86 (.034) ref 0.65 (.0256) bsc 0 ? 6 typ detail ?a? detail ?a? gauge plane 1 2 3 4 4.90 0.152 (.193 .006) 8 7 6 5 3.00 0.102 (.118 .004) (note 3) 3.00 0.102 (.118 .004) (note 4) 0.52 (.0205) ref 5.10 (.201) min 3.20 ? 3.45 (.126 ? .136) 0.889 0.127 (.035 .005) recommended solder pad layout 0.42 0.038 (.0165 .0015) typ 0.65 (.0256) bsc ms8 package 8-lead plastic msop (reference ltc dwg # 05-08-1660 rev g) LT6100 6100fd for more information www.linear.com/LT6100
17 revision history rev date description page number c 11/12 corrected value in output signal range section. 11 d 07/14 corrected part numbers in order information corrected specified temperature range for LT6100c updated format of order information added web links 2 2 2 all (revision history begins at rev c) 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. LT6100 6100fd for more information www.linear.com/LT6100
18 ? linear technology corporation 2005 lt 0714 rev d ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/LT6100 related parts typical applications 800ma/1a white led current regulator v in d1: diodes inc. d2: lumileds lxml-pw09 white emitter l1: sumida cdrh6d28-3r0 0.1f 22f 16v cer 1210 4.99k 6100 ta02 124k 8.2k mmbt2222 lt3436 d1 b130 l1 3h shdn v sw fb gnd led on v in 3.3v to 4.2v single li-ion 4.7f 6.3v cer v c v s + 0.030 d2 led warning! very bright do not observe directly led current v out v ee a4 LT6100 open: 1a closed: 800ma a2 v s ? v cc + ? filtered gain of 20 current sense gain of 50 current sense v out 20 r sense i sense ?3db at 2.6khz fil v cc 6100 ta03 r sense LT6100 v s ? v s + v ee a2 a4 3v 1000pf v supply 4.4v to 48v i sense load ? + v out 50 r sense i sense fil v cc 6100 ta04 r sense LT6100 v s ? v s + v ee a2 a4 5v v supply 6.4v to 48v i sense ? + load part number description comments lt c ? 1043 dual precision instrumentation switched capacitor building block 120db cmrr, 3v to 18v operation lt1490/lt1491 dual and quad micropower rail-to-rail input and output op amps 50a amplifier, 2.7v to 40v operation, over-the- top inputs lt1620/lt1621 rail-to-rail current sense amplifiers accurate output current programming, battery charging to 32v lt1787 precision bidirectional, high side current sense amplifier 75v v os , 60 v, 60a operation ltc6101/ltc6101hv high voltage, high side, precision current sense amplifiers 4v to 60v/5v to 100v, gain configurable, sot-23 LT6100 6100fd for more information www.linear.com/LT6100

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