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max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers evaluation kit available 19-5015; rev 6; 1/15 general description the max9918/max9919/max9920 are single-supply,high-accuracy current-sense amplifiers with a high input common-mode range that extends from -20v to +75v. these amplifiers are well suited for current monitoring of inductive loads such as motors and solenoids, where common-mode voltages can become negative due to inductive kickback, reverse-battery conditions, or transient events. the max9918/max9920 feature adjustable gain set by an external resistive-divider network. the max9919 features fixed gains of 45v/v (max9919f) and 90v/v (max9919n). the max9918/max9919/max9920 operate as unidirectional amplifiers when v refin = gnd and as bidirectional amplifiers when v refin = v cc /2. the max9920 attenuates the input signal by a factor of 4at the input level-shifting stage allowing the device to sense voltages up to 200mv (unidirectional operation) or 100mv (bidirectional operation). the max9918/max9919/max9920 operate with a single 5v supply voltage, are fully specified over the -40c to +125c automotive temperature range, and are available in an 8-pin soic package. applications h-bridge motor current sensingsolenoid current sensing current monitoring of inductive loads high- and low-side precision current sensing super-capacitor charge/discharge monitoring precision high-voltage current monitoring benefits and features ? reduce protective clamping for high inductive kickback voltage ? -20v to +75v input common-mode voltage range ? supports wide range of precision ac and dc current sensing applications ? uni- or bidirectional current sensing ? 0.6% (max) gain accuracy error ? 400v (max) input offset voltage ? 120khz, -3db bandwidth (max9919n) ? reference input for bidirectional out ? rail-to-rail output ? saves board space ? 8-pin soic package ? single-supply operation (4.5v to 5.5v) m 2b 1b adc ref a input stage level shifter r sense v batt adjustable gain v cc v cc rs+ rs- fb out refin r2 r1 gnd gnd shdn 2b 1a max9918max9920 c typical operating circuit ordering information/ selector guide part v sense (mv) gain (v/v) pin-package max9918 asa+ 50 adjustable 8 so-ep* max9918asa/v+ 50 adjustable 8 so-ep* max9919 fasa+ 50 45 8 so-ep* max9919fasa/v+ 50 45 8 so-ep* MAX9919NASA+ 50 90 8 so-ep* MAX9919NASA/v+ 50 90 8 so-ep* max9920 asa+ 200 adjustable 8 so-ep* max9920asa/v+ 200 adjustable 8 so-ep* note: all devices operate over the -40c to +125c temperature range. + denotes a lead(pb)-free/rohs-compliant package. /v denotes an automotive qualified part. * ep = exposed pad. downloaded from: http:///
max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers maxim integrated | 2 www.maximintegrated.com absolute maximum ratings electrical characteristics (v cc = 5v, v rs+ = v rs- = +14v, v sense = (v rs+ - v rs- ) = 0v, v shdn = v gnd = 0v, v refin = v cc /2, r l = 100k ; for max9918, a v = 90v/v, r2/r1 = 89k /1k ; for max9920, a v = 20v/v, r2/r1 = 79k /1k ; t a = -40c to +125c, unless otherwise noted. typical val- ues are at t a = +25c.) (note 1) stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc to gnd ..............................................................-0.3v to +6v rs+, rs- to gnd (v cc = 5v) ..................................-30v to +80v rs+, rs- to gnd (v cc = 0v) .............-15v to +80v (15 minutes) differential input voltage (v rs+ - v rs- ) (max9918/max9919).................................15v (continuous) differential input voltage (v rs+ - v rs- ) (max9920) .............................5v (continuous) refin, fb, out to gnd.............................-0.3v to (v cc + 0.3v) shdn to gnd.........................................................-0.3v to +20v output short circuit to v cc or gnd...........................continuous continuous current into any pin (not to exceed package power dissipation) ................20ma continuous power dissipation (t a = +70c) 8-pin so-ep (derate 24.4mw/c above +70c) .....1951.2mw** junction temperature ......................................................+150c storage temperature range .............................-65c to +150c lead temperature (soldering, 10s) .................................+300c soldering temperature (reflow) .......................................+260c package thermal characteristics (note 1) so-ep junction-to-ambient thermal resistance ( ja ) ...........41c/w parameter symbol conditions min typ max units t a = +25c 0.14 0.4 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 0.7 t a = +25c 0.08 0.4 max9918 v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 1.3 t a = +25c 0.18 0.4 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 0.9 t a = +25c 0.11 0.4 max9919_ v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 1.0 t a = +25c 0.48 1.2 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 3.0 t a = +25c 0.10 0.9 input offset voltage (note 2) v os max9920 v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 3.5 mv note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layerboard. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . ** as per jedec51 standard (multilayer board). downloaded from: http:///
-20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 3 www.maximintegrated.com parameters symbol conditions min typ max units v rs+ = v rs- = +14v 1.2 max9918 v rs+ = v rs- = -2v 3.3 v rs+ = v rs- = +14v 1.8 max9919_ v rs+ = v rs- = -2v 1.8 v rs+ = v rs- = +14v 2.4 input offset voltage drift(note 3) v osd max9920 v rs+ = v rs- = -2v 8.8 v/c common-mode range v cm inferred from cmrr tests -20 +75 v -2v v cm +14v 80 m ax 9918, m ax 9919 -20v v cm +75v 96 -2v v cm +14v 72 common-mode rejection ratio(note 3) cmrr max9920 -20v v cm +75v 86 db t a = +25c 175 input bias current i rs+ , i rs- -20v v cm +75v t a = -40c to +125c 250 a input offset current ( i rs + - i rs - ) 0 8 a input leakage current inshutdown -20v v cm +75v, v shdn = v cc = 5v 30 a input leakage current v rs+ = v rs- = +14v, +75v, v cc = 0v 30 a common mode 300 k max9918,max9919_ differential 715 common mode 330 k input resistance max9920 differential 224 max9918, max9919_ 50 full-scale sense voltage (note 4) v sense inferred from gainerror test max9920 200 mv max9918, max9920 adj max9919f 45 gain (notes 2, 4) g max9919n 90 v/v max9918 30 minimum adjustable gain g adj max9920 7.5 v/v electrical characteristics (continued) (v cc = 5v, v rs+ = v rs- = +14v, v sense = (v rs+ - v rs- ) = 0v, v shdn = v gnd = 0v, v refin = v cc /2, r l = 100k ; for max9918, a v = 90v/v, r2/r1 = 89k /1k ; for max9920, a v = 20v/v, r2/r1 = 79k /1k ; t a = -40c to +125c, unless otherwise noted. typical val- ues are at t a = +25c.) (note 1) downloaded from: http:///
max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers maxim integrated | 4 www.maximintegrated.com electrical characteristics (continued) (v cc = 5v, v rs+ = v rs- = +14v, v sense = (v rs+ - v rs- ) = 0v, v shdn = v gnd = 0v, v refin = v cc /2, r l = 100k ; for max9918, a v = 90v/v, r2/r1 = 89k /1k ; for max9920, a v = 20v/v, r2/r1 = 79k /1k ; t a = -40c to +125c, unless otherwise noted. typical val- ues are at t a = +25c.) (note 1) parameter symbol conditions min typ max units t a = +25c, v refin = 0v 0.08 0.6 v rs+ = v rs- = +14v t a = -40c to +125c,v refin = 0v 1.2 t a = +25c 0.02 0.6 max9918 v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 1.0 t a = +25c 0.13 0.45 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 1.2 t a = +25c 0.10 0.45 max9919f v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 0.9 t a = +25c 0.16 0.6 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 1.2 t a = +25c 0.11 0.6 max9919n v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 1.0 t a = +25c 0.29 1.0 v rs+ = v rs- = +14v, v refin = 0v t a = -40c to +125c 1.7 t a = +25c 0.24 1.0 gain error(note 2) ge max9920 v rs+ = v rs- = -2v, v refin = 0v t a = -40c to +125c 1.7 % fb input bias current i fb max9918, max9920 5 15 na r l = 100k to gnd 3 10 output-voltage high (note 4) v cc - v oh v sense = 200mv for max9918, max9919_,v sense = 400mv for max9920 r l = 10k to gnd 12 40 mv r l = 100k to v cc 31 0 output-voltage low (note 4) v ol v sense = -200mv for max9918, max9919_,v sense = -400mv for max9920 r l = 10k to v cc 10 40 mv out shorted to v cc 44 short-circuit current i sc out shorted to gnd 41 ma output resistance r out 0.1 m ax 9918, m ax9919_ 0 v cc /2 v cc - 1.9 refin voltage range inferred from refincmrr test max9920 0 v cc /2 v cc - 2.4 v downloaded from: http:///
-20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 5 www.maximintegrated.com electrical characteristics (continued) (v cc = 5v, v rs+ = v rs- = +14v, v sense = (v rs+ - v rs- ) = 0v, v shdn = v gnd = 0v, v refin = v cc /2, r l = 100k ; for max9918, a v = 90v/v, r2/r1 = 89k /1k ; for max9920, a v = 20v/v, r2/r1 = 79k /1k ; t a = -40c to +125c, unless otherwise noted. typical val- ues are at t a = +25c.) (note 1) parameters symbol conditions min typ max units max9918, max9919_ 0v v refin (v cc - 1.9v) 82 103 refin common-mode rejectionratio re fin c m r r max9920 0v v refin (v cc - 2.4v) 75 90 db m ax 9918, m ax 9919_, v rs + = v rs - = 50m v 100 refin current i refin max9920, v rs+ = v rs- = 200mv 100 a shdn logic-high v ih 2.0 v shdn logic-low v il 0.8 v shdn logic input current 0 v shdn v cc 5 a supply voltage range v cc inferred from psrr test 4.5 5.5 v max9918, max9919_ 4.5v v cc 5.5v 74 103 power-supply rejection ratio(note 3) psrr max9920 4.5v v cc 5.5v 68 100 db t a = +25c 0.7 1.2 v rs+ = v rs- = +14v t a = - 40c to + 125c 1.5 t a = +25c 1.0 1.6 supply current i cc v rs+ = v rs- = -2v t a = - 40c to + 125c 2.2 ma shutdown supply current i cc_shdn v shdn = v cc = 5v 0.5 10 a max9918, v sense = 50mv 75 max9919f, v sense = 50mv 250 max9919n, v sense = 50mv 120 small signal -3db bandwidth bw max9920, v sense = 200mv 230 khz max9918 0.6 max9919f 0.9 max9919n 3.0 slew rate sr max9920 1.5 v/s v sense = 5mv to 50mv step 12 max9918 v sense = 50mv to 5mv step 7 v sense = 5mv to 50mv step 3.5 max9919f v sense = 50mv to 5mv step 2.5 v sense = 5mv to 50mv step 3.5 max9919n v sense = 50mv to 5mv step 3 v s e n s e = 20m v to 200m v step 5 1% settling time from v sense step max9920 v s e n s e = 200m v to 20m v step 3 s downloaded from: http:///
max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers maxim integrated | 6 www.maximintegrated.com electrical characteristics (continued) (v cc = 5v, v rs+ = v rs- = +14v, v sense = (v rs+ - v rs- ) = 0v, v shdn = v gnd = 0v, v refin = v cc /2, r l = 100k ; for max9918, a v = 90v/v, r2/r1 = 89k /1k ; for max9920, a v = 20v/v, r2/r1 = 79k /1k ; t a = -40c to +125c, unless otherwise noted. typical val- ues are at t a = +25c.) (note 1) parameters symbol conditions min typ max units v cm = -2v to +14v step 2.5 max9918,v sense = 50mv v cm = +14v to -2v step 0.5 v cm = -2v to +14v step 2.5 max9919f,v sense = 50mv v cm = +14v to -2v step 0.5 v cm = -2v to +14v step 3.5 max9919n,v sense = 50mv v cm = +14v to -2v step 3.5 v cm = -2v to +14v step 0.25 1% settling time from v cm step max9920,v sense = 200mv v cm = +14v to -2v step 2.5 s max9918, v sense = 50mv, 1% settling 4.5 max9919f, v sense = 50mv, 1% settling 5 max9919n, v sense = 50mv, 1% settling 6 power-up time max9920, v sense = 200mv, 1% settling 5 s max capacitive load stability no sustained oscillations (note 5) 50 pf max9918, max9919_ 60 input-referred noise voltagedensity e n 10khz max9920 174 nv/ hz note 1: all devices are 100% production tested at t a = +25c. all temperature limits are guaranteed by design. note 2: v os is extrapolated from two point gain error tests. measurements are made at v sense = 5mv and 50mv for max9918/max9919n/max9919f, and v sense = 20mv and 200mv for max9920. note 3: extrapolated v os as described above in note 2 is used to calculate v os drift, cmrr, and psrr. note 4: out should be 100mv away from either rail to achieve rated accuracy, or limited by a v sense of 50mv for the max9918/max9919n/max9919f and 200mv for the max9920. note 5: not production tested. guaranteed by design. downloaded from: http:///
-20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 7 www.maximintegrated.com typical operating characteristics (v cc = 5v, t a = +25c, unless otherwise noted.) v os (v rs+ = +14v) max9918 toc01 offset voltage ( f v) n (%) 240 320 -240-160 -80 0 80 160 -320 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0 -400 400 v os drift (v rs+ = +14v) max9918 toc02 offset voltage ( f v/ c) n (%) 3 2 1 0 -1 -2 -3 0.05 0.10 0.15 0.20 0.25 0.30 0 -4 4 v os (v rs+ = -2v) max9918 toc03 offset voltage ( f v) n (%) 320 240 160 800 -80 -160 -240 -320 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 -400 400 v os drift (v rs+ = -2v) max9918 toc04 offset voltage ( f v/ c) n (%) 8 46 -6 -4 -2 0 2 -8 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0 -10 10 v os vs. v cm max9918 toc05 v cm (v) v os (uv) 70 60 40 50 0 10 20 30 -10 -400 -300 -200 -100 0 100 200 300 400 500 -500 -20 80 t a = -40c t a = +25c max9918asav cc = 5v v ref = v gnd t a = +125c v os vs. v cc max9918 toc06 v cc (v) vos ( f v) 5.4 5.3 5.1 5.2 4.7 4.8 4.9 5.0 4.6 -75 -50 -25 0 25 50 75 100 125 -100 4.5 5.5 max9918asav cc = 5v v ref = v gnd v cm = -2v v cm = 14v 0 0.1 0.2 0.3 -0.4 -0.3 -0.2 -0.1 0.4 gain error (v rs+ = +14v, max9919f, a v = +45v/v) max9918 toc07 gain error (%) n (%) 0.1 0.2 0.3 0.4 0.5 0.6 0 0 0.1 0.2 0.3 -0.4 -0.3 -0.2 -0.1 0.4 gain error (%) max9918 toc08 n (%) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 gain error (v rs+ = +14v, max9919n, a v = +90v/v) 0 0.1 0.2 0.3 -0.4 -0.3 -0.2 -0.1 0.4 gain error (v rs+ = -2v, max9919f, a v = +45v/v) max9918 toc09 gain error (%) n (%) 0.1 0.2 0.3 0.4 0.5 0.6 0 downloaded from: http:///
maxim integrated | 8 www.maximintegrated.com max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) 0 0.1 0.2 0.3 -0.4 -0.3 -0.2 -0.1 0.4 gain error (v rs+ = -2v, max9919n, a v = +90v/v) max9918 toc10 gain error (%) n (%) 0.1 0.2 0.3 0.4 0.5 0.6 0 gain error vs. v cm max9918 toc11 v cm (v) ge (%) 70 60 40 50 0 10 20 30 -10 -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2.0 -2.0 -20 80 max9918asav cc = 5v v ref = v gnd t a = +125 n c t a = +25 n c t a = -40 n c gain error vs. v cc max9918 toc12 v cc (v) gain error (%) 5.3 5.1 4.9 4.7 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -0.5 4.5 5.5 v cm = -2v v cm = 14v linearity vs. v sense max9918 toc13 linearity (%) 20 10 0 -10 -20 -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0.25 -0.25 -30 30 v cm = -2v v cc = 5v v refin = v cc /2 a v = 90v/v bidirectional t a = -40c v sense (mv) t a = +25c t a = +125c linearity vs. v sense max9918 toc14 linearity (%) 20 10 0 -10 -20 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.10 -0.10 -30 30 v cm = +14v v cc = 5v v refin = v cc /2 a v = 90v/v bidirectional t a = -40c t a = +25c t a = +125c v sense (mv) linearity vs. v sense max9918 toc15 linearity (%) 70 60 40 50 20 30 10 08 0 v cm = -2v v cc = 5v v refin = v gnd a v = 90v/v unidirectional t a = -40c t a = +25c t a = +125c -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.10 -0.10 v sense (mv) downloaded from: http:///
maxim integrated | 9 www.maximintegrated.com -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) v out - v refin vs. v sense max9918 toc19 v out - v refin (v) 70 60 40 50 0 10 20 30 -10 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 -1.0 -20 80 max9918, v refin = 0v unidirectional,gain = 90v/v -2v v cm : solid line 14v v cm : dashed line v sense (mv) v out - v refin vs. v sense max9918 toc20 v sense (mv) v out - v refin (v) 30 20 0 10 -20 -10 -30 -2.5 -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 -3.0 -40 40 max9918, v refin = v cc /2 bidirectional,gain = 90v/v -2v v cm : solid line 14v v cm : dashed line v oh /v ol vs. i oh max9918 toc21 i oh (ma) v oh and v ol (mv) 9 8 7 6 5 4 3 2 1 50 100 150 200 250 300 350 0 01 0 v cc - v oh v cm = +14v v ol linearity vs. v sense max9918 toc16 v sense (mv) linearity (%) 65 6055 40 45 50 10 15 20 25 30 35 5 -0.08 0.02 0.04 0.06 0 -0.02-0.04 -0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 -0.10 07 0 v cm = +14v v cc = 5v v refin = v gnd a v = 90v/v unidirectional t a = -40c t a = +25c t a = +125c linearity vs. v sense max9918 toc17 v sense (mv) linearity (%) 80 60 02040 -60 -40 -20 -80 -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0.25 -0.25 -100 100 v cm = -2v v cc = 5v v refin = v cc /2 a v = 30v/v bidirectional t a = +25c t a = +125c t a = -40c linearity vs. v sense max9918 toc18 v sense (mv) linearity (%) 80 60 02040 -60 -40 -20 -80 -100 100 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.10 -0.10 v cm = +14v v cc = 5v v refin = v cc /2 a v = 30v/v bidirectional t a = +25c t a = +125c t a = -40c downloaded from: http:///
maxim integrated | 10 www.maximintegrated.com max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) i cc vs. v cc max9918 toc22 v cc (v) i cc (ma) 5.4 5.3 5.1 5.2 4.7 4.8 4.9 5.0 4.6 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 4.5 5.5 v cm = 14v v sense = 0v v cm = -2v i cc vs.v cm max9918 toc23 v cm (v) i cc (ma) 70 60 40 50 0 10 20 30 -10 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.60.4 -20 80 t a = +125 n c t a = +25 n c t a = -40 n c v sense = 0v (dash) v sense + 50mv (solid) i bias vs. v cm max9918 toc24 v cm (v) i bais ( f a) 70 60 40 50 0 10 20 30 -10 -80 -60 -40 -20 0 20 40 60 80 100 -100 -20 80 max9918v cc = 5v input leakage current vs. v cm max9918 toc25 v cm (v) input leakage current ( f a) 60 40 20 0 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 -50 -20 80 in+ - in- = 50mvv cc = v shdn = 0v v refin = 0v t a = +125 n c t a = +25 n c t a = -40 n c differential r in vs. v cm max9918 toc26 v cm (v) differential r in ( i ) 55 40 25 10 -5 100 200 300 400 500 600 700 800 900 1000 0 -20 70 gain vs. frequency max9918 toc27 frequency (mhz) gain (db) 1 0.1 0.01 -30 -20 -10 0 10 20 30 40 50 -40 0.001 10 max9918v cm = 14v gain = 90v/v gain vs. frequency max9918 toc28 frequency (mhz) gain (db) 1 0.1 0.01 -50 -40 -30 -20 -10 0 10 20 30 40 -60 0.001 10 max9920v cm = 14v gain = 20v/v gain vs. frequency max9918 toc29 frequency (mhz) gain (db) 10 1 0.1 0.01 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 -100 0.001 100 max9918v cm = 14v gain = 90v/v v cm = -2v v cm = 14v psrr vs. frequency max9918 toc30 frequency (khz) psrr (db) 1k 100 10 1 0.1 0.01 0.001 -120 -100 -80 -60 -40 -20 0 -140 0.0001 10k max9918v cm = 14v v sense = 50mv downloaded from: http:///
maxim integrated | 11 www.maximintegrated.com -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) small-signal transient (gain = 45v/v) max9918 toc31 50mv/div 10 f s/div 5mv/div max9918, v cm = 14v v sense = 10mv to 15mv small-signal transient (gain = 90v/v) max9918 toc32 100mv/div 10 f s/div 5mv/div max9918, v cm = 14v v sense = 10mv to 15mv large-signal transient (gain = 45v/v) max9918 toc33 500mv/div 10 f s/div 50mv/div max9918, v cm = 14v v sense = 0v to 50mv large-signal transient (gain = 90v/v) max9918 toc34 1v/div 10 f s/div 50mv/div max9918, v cm = 14v v sense = 0 to 50mv output response to common-mode transient max9918 toc36 v out 100mv/div v cm 50v/div 0 4s/div output ac-coupled full scale at the input common-mode step response max9918 toc35 1v/div 10 f s/div 10v/div max9918, v cm = 14v s sense = ps (50mv) downloaded from: http:///
maxim integrated | 12 www.maximintegrated.com max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) shutdown on/off delay max9918 toc37 1v/div 4 f s/div 5v/div max9918, v cm = 14v v sense = ps (50mv) output overdrive recovery (30v/v) max9918 toc39 2v/div 4 f s/div 200mv/div max9918, v cm = 14v v sense = 2 x ps power-up time max9918 toc38 2v/div 4 f s/div 5v/div max9918, v cm = 14v v sense = ps (50mv) output overdrive recovery (90v/v) max9918 toc40 2v/div 4 f s/div 50mv/div max9918, v cm = 14v v sense = 2 x ps downloaded from: http:///
detailed description the max9918/max9919/max9920 are single-supply,high-accuracy uni-/bidirectional current-sense amplifiers with a high common-mode input range that extends from -20v to +75v. the max9918/max9919/max9920s input stage utilizes a pair of level shifters allowing a wide common-mode operating range when measuring the voltage drop (v sense ) across the current-sense resistor. the first level shifter accommodates the upper common-mode operating range from +2v to +75v. when the common-mode voltage falls below +2v, the second level shifter is used to accommodate negative voltages down to -20v. the level shifters translate v sense to an internal refer- ence voltage where it is then amplified with an instru-mentation amplifier. the instrumentation amplifier configuration provides high precision with input offset voltages of 400v (max). indirect feedback of the instrumentation amplifier allows the gain to be adjusted with an external resistive-divider network on the max9918/max9920. the max9919 is a fixed gain device available with laser-trimmed resistors for gains of 45v/v (max9919f) and 90v/v (max9919n). the max9918/max9919 operate with a full-scale sense voltage of 50mv. the input stage of the max9920 pro- vides an attenuation factor of 4, enabling a full-scale sense voltage of 200mv. -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 13 www.maximintegrated.com pin name function 1 rs+ positive current-sensing input. power side connects to external sense resistor. 2 rs- negative current-sensing input. load side connects to external sense resistor. 3 shdn active-high shutdown input. connect to gnd for normal operation. 4 gnd ground 5 out current-sense output. v out is proportional to v sense . 6f b feedback input. connect fb to a resistive-divider network to set the gain for the max9918 andmax9920. see the adjustable gain (max9918/max9920) section for more information. leave fb unconnected for the max9919 for proper operation. 7 refin reference input. set refin to v cc /2 for bidirectional operation. set refin to gnd for unidirectional operation. 8v cc 5v supply voltage input. bypass v cc to gnd with 0.1f capacitor. e p exposed pad. connect to a large-area contiguous ground plane for improved power dissipation. donot use as the only ground connection for the part. 8 so-ep top view max9918max9919 max9920 fb out 8 7 v cc refin 6 5 gnd 12 rs- shdn rs+ 3 4 ep* + *exposed pad. connect ep to solid ground for proper thermal and electrical performance. pin configuration pin description downloaded from: http:///
max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers maxim integrated | 14 www.maximintegrated.com uni-/bidirectional operation the max9918/max9919/max9920 support both unidi- rectional and bidirectional operation. the devices oper- ate in unidirectional mode with v refin = v gnd . the output is then referenced to ground and the output volt-age v out is proportional to the positive voltage drop (v sense ) from rs+ to rs- (figure 1). the max9918/max9919 operate in bidirectional modeby application of a low-source impedance reference voltage in the 0v to v cc - 1.9v range, (typically v cc /2), to refin. for the max9920, the reference voltage rangeis 0v to v cc - 2.4v (typically v cc /2). the output voltage v out relative to v refin is then proportional to the v sense voltage drop from rs+ to rs- (figure 2). i discharge r sense load to adc v cc gnd rs+ rs- refin out 40mv 10mv 30mv 20mv 0 dischargecurrent 0.9v 3.6v 2.7v g = 90v/v 5v 1.8v shdn max9919n v sense v out figure 1. unidirectional operation i discharge r sense i charge load to adc 2.5v v cc gnd rs+ rs- refin out -20mv 10mv 20mv 0 dischargecurrent chargecurrent -1.8v 1.8v 0.9v g = 90v/v v sense 5v -0.9v -10mv shdn v out - v refin max9919n figure 2. bidirectional operation downloaded from: http:///
-20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 15 www.maximintegrated.com shutdown mode drive shdn high to enter low-power shutdown mode. in shutdown mode, the max9918/max9919/max9920 draw 0.5a (typ) of quiescent current. adjustable gain (max9918/max9920) the max9918/max9920 feature externally adjustable gain set by a resistive-divider network circuit using resistors r1 and r2 (see the functional diagram ). the gain frequency compensation is set for a minimum gainof 30v/v for the max9918 and 7.5v/v for the max9920. the gain g for the max9918/max9920 is given by the following equation: applications information component selection ideally, the maximum load current develops the full- scale sense voltage across the current-sense resistor. choose the gain needed to yield the maximum output voltage required for the application: v out = v sense x g where v sense is the full-scale sense voltage, 50mv for the max9918/max9919, or 200mv for the max9920and g is the gain of the device. g is externally adjustable for the max9918/max9920. the max9919 has a fixed gain version of 45v/v (max9919f) or 90v/v (max9919n). in unidirectional applications (v refin = 0v), select the gain of the max9918/max9920 to utilize the full outputrange between gnd and v cc . in bidirectional applica- tions (v refin = v cc /2), select the gain to allow an output voltage range of v cc /2. v out must be at least 100mv from either rail to achieve the rated gain accuracy. sense resistor, r sense choose r sense based on the following criteria: accuracy: a high r sense value allows lower currents to be measured more accurately. this is because off-sets become less significant when the sense voltage is larger. in the linear region (100mv < v out < v cc - 100mv), there are two components to accuracy: inputoffset voltage (v os ) and gain error (ge). use the linear equation to calculate total error: v out = (g ge) x (v sense v os ) for best performance, select r sense to provide approximately 50mv (max9918/max9919) or 200mv(max9920) of sense voltage for the full-scale current in each application. sense resistors of 5m to 100m are available with 1% accuracy or better. efficiency and power dissipation at high current levels, the i 2 r losses in r sense can be significant. take this into consideration when choosingthe resistor value and its power dissipation (wattage) rating. also, the sense resistors value might drift if it is allowed to heat up excessively. the precision v os of the max9918/max9919/max9920 allows the use ofsmall sense resistors to reduce power dissipation and reduce hot spots. inductance: keep inductance low if i sense has a large high-frequency component by using resistors with lowinductance value. power-supply bypassing and grounding bypass the max9918/max9919/max9920s v cc to ground with a 0.1f capacitor. grounding thesedevices requires no special precautions; follow the same cautionary steps that apply to the rest of the sys- tem. high-current systems can experience large volt- age drops across a ground plane, and this drop may add to or subtract from v out . using a differential mea- surement between out and refin prevents this prob-lem. for highest current-measurement accuracy, use a single-point star ground. connect the exposed pad to a solid ground to ensure optimal thermal performance. ( g r r f =+ ? ? ? ? ? ? 1 2 1 o or max and g 9918 1 ) = ++ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? r r for max 2 1 4 9920 () downloaded from: http:///
max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers maxim integrated | 16 www.maximintegrated.com a input input stage/ level shifter fixed gain g = 45v/v or 90v/v v cc rs+ rs- fb out refin r2 r1 gnd shdn max9919f i load 50mv (typ) r sense a input input stage/ level shifter adjustable gain v cc rs+ rs- fb out refin r2 r1 gnd shdn max9918max9920 i load max991850mv (typ) max9920 200mv (typ) r sense gain is set by external resistors, r1 and r2g = [1+(r2/r1)] for max9918 g = [1+(r2/r1)]/4 for max9920 functional diagram chip information process: bicmos downloaded from: http:///
-20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers max9918/max9919/max9920 maxim integrated | 17 www.maximintegrated.com package type package code outline no. land pattern no. 8 so-ep s8e+14 21-0111 90-0151 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. downloaded from: http:///
maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. ? 2015 maxim integrated products, inc. | 18 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. max9918/max9919/max9920 -20v to +75v input range, precision uni-/bidirectional, current-sense amplifiers revision history revision number revision date description pages changed 0 10/09 initial release 1 1/10 updated functional diagram 16 2 12/10 added automotive qualified part 1 3 6/11 added max9920asa/v+ to data sheet 1 4 7/11 added automotive qualified parts for the MAX9919NASA/v+ and the max9920asa/v+ 1 5 1/13 added automotive qualified part for the max9919fasa/v+ 1 6 1/15 updated applications and benefits and features section 1 downloaded from: http:///

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