Precision Uni-/Bidirectional, Current-Sense Amplifiers

Transcription

1 /MAX9919/MAX992 General Description The /MAX9919/MAX992 are single-supply, high-accuracy current-sense amplifiers with a high input common-mode range that extends from -2V 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 /MAX992 feature adjustable gain set by an external resistive-divider network. The MAX9919 features fixed gains of 45V/V (MAX9919F) and 9V/V (MAX9919N). The /MAX9919/MAX992 operate as unidirectional amplifiers when V REFIN = GND and as bidirectional amplifiers when V REFIN = V CC /2. The MAX992 attenuates the input signal by a factor of 4 at the input level-shifting stage allowing the device to sense voltages up to 2mV (unidirectional operation) or ±1mV (bidirectional operation). The /MAX9919/MAX992 operate with a single 5V supply voltage, are fully specified over the -4 C to automotive temperature range, and are available in an 8-pin SOIC package. Applications H-Bridge Motor Current Sensing Solenoid Current Sensing Current Monitoring of Inductive Loads High- and Low-Side Precision Current Sensing Super-Capacitor Charge/Discharge Monitoring Precision High-Voltage Current Monitoring Typical Operating Circuit Features Reduce Protective Clamping for High Inductive Kickback Voltage -2V to +75V Input Common-Mode Voltage Range Supports Wide Range of Precision AC and DC Current Sensing Applications Uni- or Bidirectional Current Sensing.6% (max) Gain Accuracy Error 4µV (max) Input Offset Voltage 12kHz, -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) Ordering Information/ Selector Guide PART -2V to +75V Input Range, VSENSE (mv) GAIN (V/V) PIN- PACKAGE ASA+ ±5 Adjustable 8 SO-EP* ASA/V+ ±5 Adjustable 8 SO-EP* MAX9919FASA+ ± SO-EP* MAX9919FASA/V+ ± SO-EP* MAX9919NASA+ ±5 9 8 SO-EP* MAX9919NASA/V+ ±5 9 8 SO-EP* MAX992ASA+ ±2 Adjustable 8 SO-EP* MAX992ASA/V+ ±2 Adjustable 8 SO-EP* Note: All devices operate over the -4 C to temperature range. +Denotes a lead(pb)-free/rohs-compliant package. /V denotes an automotive qualified part. *EP = Exposed pad. V BATT V CC V CC ø1a R SENSE M ø2b RS+ MAX992 A OUT FB R2 ADC ø2b RSø1B INPUT STAGE LEVEL SHIFTER SHDN GND ADJUSTABLE GAIN REFIN R1 REF µc GND ; Rev 7; 1/17

2 /MAX9919/MAX992-2V to +75V Input Range, Absolute Maximum Ratings V CC to GND...-.3V to +6V RS+, RS- to GND (V CC = 5V)...-3V to +8V RS+, RS- to GND (V CC = V)...-15V to +8V (15 minutes) Differential Input Voltage (V RS+ - V RS- ) (/MAX9919)...±15V (Continuous) Differential Input Voltage (V RS+ - V RS- ) (MAX992)...±5V (Continuous) REFIN, FB, OUT to GND V to (V CC +.3V) SHDN to GND...-.3V to +2V **As per JEDEC51 Standard (multilayer board). Package Thermal Characteristics (Note 1) Output Short Circuit to V CC or GND...Continuous Continuous Current into Any Pin (Not to exceed package power dissipation)...±2ma Continuous Power Dissipation (T A = +7 C) 8-Pin SO-EP (derate 24.4mW/ C above +7 C) mW** Junction Temperature C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s)...+3 C Soldering Temperature (reflow) C SO-EP Junction-to-Ambient Thermal Resistance (θ JA )...41 C/W Junction-to-Case Thermal Resistance (θ JC )...7 C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to 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. Electrical Characteristics (V CC = 5V, +14V, V SENSE = (V RS+ - V RS- ) = V, V SHDN = V GND = V, V REFIN = V CC /2, R L = 1kΩ; for, A V = 9V/V, R2/R1 = 89kΩ/1kΩ; for MAX992, A V = 2V/V, R2/R1 = 79kΩ/1kΩ; T A = -4 C to, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS T A = +25 C ±.14 ±.4 +14V, V REFIN T A = -4 C to = V ±.7 Input Offset Voltage (Note 2) V OS MAX9919_ MAX992-2V, V REFIN = V +14V, V REFIN = V -2V, V REFIN = V +14V, V REFIN = V -2V, V REFIN = V T A = +25 C ±.8 ±.4 T A = -4 C to ±1.3 T A = +25 C ±.18 ±.4 T A = -4 C to ±.9 T A = +25 C ±.11 ±.4 T A = -4 C to ±1. T A = +25 C ±.48 ±1.2 T A = -4 C to ±3. T A = +25 C ±.1 ±.9 T A = -4 C to ±3.5 mv Maxim Integrated 2

3 /MAX9919/MAX992-2V to +75V Input Range, Electrical Characteristics (continued) (V CC = 5V, +14V, V SENSE = (V RS+ - V RS- ) = V, V SHDN = V GND = V, V REFIN = V CC /2, R L = 1kΩ; for, A V = 9V/V, R2/R1 = 89kΩ/1kΩ; for MAX992, A V = 2V/V, R2/R1 = 79kΩ/1kΩ; T A = -4 C to, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS +14V ±1.2-2V ±3.3 Input Offset Voltage Drift +14V ±1.8 V (Note 3) OSD MAX9919_ µv/ C -2V ± V ±2.4 MAX992-2V ±8.8 Common-Mode Range V CM Inferred from CMRR tests V, -2V V CM +14V 8 MAX9919 Common-Mode Rejection Ratio -2V V CM +75V 96 CMRR db (Note 3) -2V V CM +14V 72 MAX992-2V V CM +75V 86 Input Bias Current I RS+, I RS- -2V V CM +75V T A = +25 C ±175 µa T A = -4 C to ±25 Input Offset Current (I RS+ - I RS- ) ±8 µa Input Leakage Current in Shutdown -2V V CM +75V, V SHDN = V CC = 5V ±3 µa Input Leakage Current +14V, +75V, V CC = V ±3 µa, Common mode 3 kω MAX9919_ Differential 715 Ω Input Resistance Common mode 33 kω MAX992 Differential 224 Ω Full-Scale Sense Voltage Inferred from gain, MAX9919_ 5 V (Note 4) SENSE error test MAX992 2 mv, MAX992 Adj Gain (Notes 2, 4) G MAX9919F 45 V/V MAX9919N 9 3 Minimum Adjustable Gain G ADJ MAX V/V Maxim Integrated 3

4 /MAX9919/MAX992-2V to +75V Input Range, Electrical Characteristics (continued) (V CC = 5V, +14V, V SENSE = (V RS+ - V RS- ) = V, V SHDN = V GND = V, V REFIN = V CC /2, R L = 1kΩ; for, A V = 9V/V, R2/R1 = 89kΩ/1kΩ; for MAX992, A V = 2V/V, R2/R1 = 79kΩ/1kΩ; T A = -4 C to, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS +14V T A = +25 C, V REFIN = V T A = -4 C to, V REFIN = V ±.8 ±.6 ±1.2-2V, V REFIN = V T A = +25 C ±.2 ±.6 T A = -4 C to ±1. Gain Error (Note 2) GE MAX9919F MAX9919N +14V, V REFIN = V -2V, V REFIN = V +14V, V REFIN = V -2V, V REFIN = V T A = +25 C ±.13 ±.45 T A = -4 C to ±1.2 T A = +25 C ±.1 ±.45 T A = -4 C to ±.9 T A = +25 C ±.16 ±.6 T A = -4 C to ±1.2 T A = +25 C ±.11 ±.6 T A = -4 C to ±1. % MAX V, V REFIN = V -2V, V REFIN = V T A = +25 C ±.29 ±1. T A = -4 C to ±1.7 T A = +25 C ±.24 ±1. T A = -4 C to ±1.7 Output-Voltage High (Note 4) V CC - V OH, MAX9919_, V SENSE = 4mV for V SENSE = 2mV for MAX992 Output-Voltage Low (Note 4) V OL, MAX9919_, V SENSE = -4mV for V SENSE = -2mV for MAX992 R L = 1kΩ to GND 3 1 R L = 1kΩ to GND 12 4 R L = 1kΩ to V CC 3 1 RL = 1kΩ to V CC 1 4 OUT shorted to V CC 44 Short-Circuit Current I SC ma OUT shorted to GND 41 Output Resistance R OUT.1 Ω REFIN Voltage Range Inferred from REFIN CMRR test, MAX9919_ V CC /2 MAX992 V CC /2 V CC V CC mv mv V Maxim Integrated 4

5 /MAX9919/MAX992-2V to +75V Input Range, Electrical Characteristics (continued) (V CC = 5V, +14V, V SENSE = (V RS+ - V RS- ) = V, V SHDN = V GND = V, V REFIN = V CC /2, R L = 1kΩ; for, A V = 9V/V, R2/R1 = 89kΩ/1kΩ; for MAX992, A V = 2V/V, R2/R1 = 79kΩ/1kΩ; T A = -4 C to, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS REFIN Common-Mode Rejection Ratio REFIN CMRR, MAX9919_ MAX992 V V REFIN (V CC - 1.9V) V V REFIN (V CC - 2.4V) , MAX9919_, ±5mV ±1 REFIN Current I REFIN MAX992, ±2mV ±1 µa SHDN Logic-High V IH 2. V SHDN Logic-Low V IL.8 V SHDN Logic Input Current V SHDN V CC 5 µa Supply Voltage Range V CC Inferred from PSRR test V Power-Supply Rejection Ratio, MAX9919_ 4.5V V CC 5.5V PSRR (Note 3) MAX V V CC 5.5V 68 1 db Supply Current I CC +14V T A = +25 C T A = -4 C to 1.5-2V T A = +25 C T A = -4 C to 2.2 ma Shutdown Supply Current I CC_SHDN V SHDN = V CC = 5V.5 1 µa, V SENSE = 5mV 75 Small Signal -3dB Bandwidth BW MAX9919F, V SENSE = 5mV 25 MAX9919N, V SENSE = 5mV 12 khz MAX992, V SENSE = 2mV 23.6 Slew Rate SR MAX9919F.9 MAX9919N 3. V/µs MAX V SENSE = 5mV to 5mV step 12 V SENSE = 5mV to 5mV step 7 1% Settling Time from V SENSE Step MAX9919F V SENSE = 5mV to 5mV step 3.5 V SENSE = 5mV to 5mV step 2.5 MAX9919N V SENSE = 5mV to 5mV step 3.5 V SENSE = 5mV to 5mV step 3 V SENSE = 2mV to 2mV step 5 MAX992 V SENSE = 2mV to 2mV step 3 db µs Maxim Integrated 5

6 /MAX9919/MAX992-2V to +75V Input Range, Electrical Characteristics (continued) (V CC = 5V, +14V, V SENSE = (V RS+ - V RS- ) = V, V SHDN = V GND = V, V REFIN = V CC /2, R L = 1kΩ; for, A V = 9V/V, R2/R1 = 89kΩ/1kΩ; for MAX992, A V = 2V/V, R2/R1 = 79kΩ/1kΩ; T A = -4 C to, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS, V CM = -2V to +14V step 2.5 V SENSE = 5mV V CM = +14V to -2V step.5 MAX9919F, V CM = -2V to +14V step 2.5 1% Settling Time from VCM Step V SENSE = 5mV V CM = +14V to -2V step.5 MAX9919N, V CM = -2V to +14V step 3.5 µs V SENSE = 5mV V CM = +14V to -2V step 3.5 MAX992, V CM = -2V to +14V step.25 V SENSE = 2mV V CM = +14V to -2V step 2.5, V SENSE = 5mV, 1% settling 4.5 Power-Up Time MAX9919F, V SENSE = 5mV, 1% settling 5 MAX9919N, V SENSE = 5mV, 1% settling 6 µs MAX992, V SENSE = 2mV, 1% settling 5 Max Capacitive Load Stability No sustained oscillations (Note 5) 5 pf Input-Referred Noise Voltage, MAX9919_ 6 e Density n 1kHz MAX nv/ Hz Note 1: All devices are 1% production tested at T A = +25 C. 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 5mV for / MAX9919N/MAX9919F, and V SENSE = 2mV and 2mV for MAX992. 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 1mV away from either rail to achieve rated accuracy, or limited by a V SENSE of 5mV for the / MAX9919N/MAX9919F and 2mV for the MAX992. Note 5: Not production tested. Guaranteed by design. Maxim Integrated 6

7 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (V CC = 5V, T A = +25 C, unless otherwise noted.) V OS (V RS+ = +14V) toc V OS DRIFT (V RS+ = +14V) toc V OS (V RS+ = -2V) toc3 N (%) N (%) N (%) OFFSET VOLTAGE (µv) OFFSET VOLTAGE (µv/ C) OFFSET VOLTAGE (µv) N (%) V OS DRIFT (V RS+ = -2V) OFFSET VOLTAGE (µv/ C) toc4 VOS (µv) V OS vs. V CM T A = -4 C ASA V CC = 5V V REF = V GND V CM (V) T A = +25 C T A = toc5 VOS (µv) V OS vs. V CC V CM = 14V -5 ASA V CM = -2V -75 V CC = 5V V REF = V GND V CC (V) toc6.6.5 GAIN ERROR (V RS+ = +14V, MAX9919F, A V = +45V/V) toc GAIN ERROR (V RS+ = +14V, MAX9919N, A V = +9V/V) toc8.6.5 GAIN ERROR (V RS+ = -2V, MAX9919F, A V = +45V/V) toc N (%).3 N (%).4 N (%) GAIN ERROR (%) GAIN ERROR (%) GAIN ERROR (%) Maxim Integrated 7

8 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (continued) (V CC = 5V, T A = +25 C, unless otherwise noted.) N (%) GAIN ERROR (V RS+ = -2V, MAX9919N, A V = +9V/V) GAIN ERROR (%) toc1 GE (%) T A = GAIN ERROR vs. V CM T A = +25 C ASA T A = -4 C -1.6 V CC = 5V V REF = V GND V CM (V) toc11 GAIN ERROR (%) GAIN ERROR vs. V CC V CM = -2V V CM = 14V V CC (V) toc12 LINEARITY (%) LINEARITY vs. V SENSE.25 V CM = -2V.2 V CC = 5V.15 V REFIN = V CC /2.1 T A = -4 C A V = 9V/V BIDIRECTIONAL T A = -.1 T A = +25 C V SENSE (mv) toc13 LINEARITY (%) LINEARITY vs. V SENSE T A = +25 C T A = -4 C T A = V CM = +14V V CC = 5V V REFIN = V CC /2 A V = 9V/V BIDIRECTIONAL V SENSE (mv) toc14 LINEARITY (%) T A = +25 C LINEARITY vs. V SENSE T A = T A = -4 C V SENSE (mv) toc15 V CM = -2V V CC = 5V V REFIN = V GND A V = 9V/V UNIDIRECTIONAL Maxim Integrated 8

9 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (continued) (V CC = 5V, T A = +25 C, unless otherwise noted.) LINEARITY (%) LINEARITY vs. V SENSE V CM = +14V V CC = 5V V REFIN = V GND A V = 9V/V UNIDIRECTIONAL T A = +25 C T A = V SENSE (mv) T A = -4 C toc16 LINEARITY (%) LINEARITY vs. V SENSE T A = +25 C T A = V CM = -2V V CC = 5V V REFIN = V CC /2 A V = 3V/V BIDIRECTIONAL T A = -4 C V SENSE (mv) toc17 LINEARITY (%) LINEARITY vs. V SENSE T A = -4 C T A = T A = +25 C V SENSE (mv) toc18 V CM = +14V V CC = 5V V REFIN = V CC /2 A V = 3V/V BIDIRECTIONAL VOUT - VREFIN (V) V OUT - V REFIN vs. V SENSE -2V V CM : SOLID LINE 14V V CM : DASHED LINE, V REFIN = V UNIDIRECTIONAL, GAIN = 9V/V V SENSE (mv) toc19 VOUT - VREFIN (V) V OUT - V REFIN vs. V SENSE -2V V CM : SOLID LINE 14V V CM : DASHED LINE, V REFIN = V CC /2 BIDIRECTIONAL, GAIN = 9V/V V SENSE (mv) toc2 VOH AND VOL (mv) V OH /V OL vs. I OH V CM = +14V V CC - V OH V OL I OH (ma) toc21 Maxim Integrated 9

10 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (continued) (V CC = 5V, T A = +25 C, unless otherwise noted.) ICC (ma) I CC vs. V CC V CM = -2V V CM = 14V V SENSE = V V CC (V) toc22 ICC (ma) T A = I CC vs.v CM T A = +25 C V SENSE = V (DASH) V SENSE + 5mV (SOLID) V CM (V) T A = -4 C toc23 IBAIS (µa) I BIAS vs. V CM -6-8 V CC = 5V V CM (V) toc24 INPUT LEAKAGE CURRENT (µa) INPUT LEAKAGE CURRENT vs. V CM T A = +25 C T A = IN+ - IN- = 5mV V CC = V SHDN = V V REFIN = V T A = -4 C V CM (V) toc25 DIFFERENTIAL RIN (Ω) DIFFERENTIAL R IN vs. V CM V CM (V) toc26 GAIN (db) GAIN vs. FREQUENCY -2-3 V CM = 14V GAIN = 9V/V FREQUENCY (MHz) toc27 GAIN (db) GAIN vs. FREQUENCY MAX992-5 V CM = 14V GAIN = 2V/V FREQUENCY (MHz) toc28 GAIN (db) GAIN vs. FREQUENCY 1 V CM = 14V -1 GAIN = 9V/V V CM = -2V V CM = 14V FREQUENCY (MHz) toc29 PSRR (db) V CM = 14V V SENSE = 5mV PSRR vs. FREQUENCY k 1k FREQUENCY (khz) toc3 Maxim Integrated 1

11 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (continued) (V CC = 5V, T A = +25 C, unless otherwise noted.) SMALL-SIGNAL TRANSIENT (GAIN = 45V/V) toc31 SMALL-SIGNAL TRANSIENT (GAIN = 9V/V) toc32 5mV/div 5mV/div 5mV/div, V CM = 14V V SENSE = 1mV TO 15mV 1mV/div, V CM = 14V V SENSE = 1mV TO 15mV 1µs/div 1µs/div LARGE-SIGNAL TRANSIENT (GAIN = 45V/V) toc33 LARGE-SIGNAL TRANSIENT (GAIN = 9V/V) toc34 5mV/div 5mV/div 5mV/div, V CM = 14V V SENSE = V TO 5mV 1V/div, V CM = 14V V SENSE = TO 5mV 1µs/div 1µs/div COMMON-MODE STEP RESPONSE toc35, V CM = 14V S SENSE = PS (5mV) OUTPUT RESPONSE TO COMMON-MODE TRANSIENT toc36 V CM 5V/div 1V/div 1V/div 1µs/div OUTPUT AC-COUPLED FULL SCALE AT THE INPUT 4µs/div V OUT 1mV/div Maxim Integrated 11

12 /MAX9919/MAX992-2V to +75V Input Range, Typical Operating Characteristics (continued) (V CC = 5V, T A = +25 C, unless otherwise noted.) SHUTDOWN ON/OFF DELAY toc37 POWER-UP TIME toc38 5V/div 5V/div 2V/div 1V/div, V CM = 14V V SENSE = PS (5mV) 4µs/div, V CM = 14V V SENSE = PS (5mV) 4µs/div OUTPUT OVERDRIVE RECOVERY (3V/V) toc39, V CM = 14V V SENSE = 2 x PS OUTPUT OVERDRIVE RECOVERY (9V/V) toc4 2mV/div 5mV/div 2V/div 4µs/div 2V/div, V CM = 14V V SENSE = 2 x PS 4µs/div Maxim Integrated 12

13 /MAX9919/MAX992-2V to +75V Input Range, Pin Configuration TOP VIEW RS V CC RS- SHDN 2 3 MAX9919 MAX REFIN FB GND 4 EP* 5 OUT 8 SO-EP *EXPOSED PAD. CONNECT EP TO SOLID GROUND FOR PROPER THERMAL AND ELECTRICAL PERFORMANCE. Pin Description 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. 6 FB 7 REFIN Feedback Input. Connect FB to a resistive-divider network to set the gain for the and MAX992. See the Adjustable Gain (/MAX992) section for more information. Leave FB unconnected for the MAX9919 for proper operation. Reference Input. Set REFIN to V CC /2 for bidirectional operation. Set REFIN to GND for unidirectional operation. 8 V CC 5V Supply Voltage Input. Bypass V CC to GND with.1µf capacitor. EP Exposed Pad. Connect to a large-area contiguous ground plane for improved power dissipation. Do not use as the only ground connection for the part. Detailed Description The /MAX9919/MAX992 are single-supply, high-accuracy uni-/bidirectional current-sense amplifiers with a high common-mode input range that extends from -2V to +75V. The /MAX9919/MAX992 s 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 commonmode voltage falls below +2V, the second level shifter is used to accommodate negative voltages down to -2V. The level shifters translate V SENSE to an internal reference voltage where it is then amplified with an instrumentation amplifier. The instrumentation amplifier configuration provides high precision with input offset voltages of 4µV (max). Indirect feedback of the instrumentation amplifier allows the gain to be adjusted with an external resistive-divider network on the /MAX992. The MAX9919 is a fixed gain device available with lasertrimmed resistors for gains of 45V/V (MAX9919F) and 9V/V (MAX9919N). The /MAX9919 operate with a full-scale sense voltage of 5mV. The input stage of the MAX992 provides an attenuation factor of 4, enabling a full-scale sense voltage of 2mV. Maxim Integrated 13

14 /MAX9919/MAX992 Uni-/Bidirectional Operation The /MAX9919/MAX992 support both unidirectional and bidirectional operation. The devices operate in unidirectional mode with V REFIN = V GND. The output is then referenced to ground and the output voltage V OUT is proportional to the positive voltage drop (V SENSE ) from RS+ to RS- (Figure 1). -2V to +75V Input Range, The /MAX9919 operate in bidirectional mode by application of a low-source impedance reference voltage in the V to V CC - 1.9V range, (typically V CC /2), to REFIN. For the MAX992, the reference voltage range is V 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). V OUT 3.6V G = 9V/V I DISCHARGE R SENSE RS+ RS- LOAD 2.7V 5V V CC MAX9919N OUT TO ADC 1.8V DISCHARGE CURRENT SHDN REFIN.9V GND 1mV 2mV 3mV 4mV V SENSE Figure 1. Unidirectional Operation V OUT - V REFIN G = 9V/V 1.8V I DISCHARGE R SENSE I CHARGE RS+ RS- LOAD.9V DISCHARGE CURRENT MAX9919N 5V V CC OUT TO ADC -2mV -1mV 1mV 2mV V SENSE SHDN GND REFIN 2.5V CHARGE CURRENT -.9V -1.8V Figure 2. Bidirectional Operation Maxim Integrated 14

15 /MAX9919/MAX992 Shutdown Mode Drive SHDN high to enter low-power shutdown mode. In shutdown mode, the /MAX9919/MAX992 draw.5µa (typ) of quiescent current. Adjustable Gain (/MAX992) The /MAX992 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 gain of 3V/V for the and 7.5V/V for the MAX992. The gain G for the /MAX992 is given by the following equation: and R2 G = 1 + (for ) R1 R2 1+ R1 G = (for MAX992) 4 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, 5mV for the /MAX9919, or 2mV for the MAX992 and G is the gain of the device. G is externally adjustable for the /MAX992. The MAX9919 has a fixed gain version of 45V/V (MAX9919F) or 9V/V (MAX9919N). In unidirectional applications (V REFIN = V), select the gain of the /MAX992 to utilize the full output range between GND and V CC. In bidirectional applications (V REFIN = V CC /2), select the gain to allow an output voltage range of ±V CC /2. V OUT must be at least 1mV from either rail to achieve the rated gain accuracy. -2V to +75V Input Range, 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 offsets become less significant when the sense voltage is larger. In the linear region (1mV < V OUT < V CC - 1mV), there are two components to accuracy: input offset 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 5mV (/MAX9919) or 2mV (MAX992) of sense voltage for the full-scale current in each application. Sense resistors of 5mΩ to 1mΩ are available with 1% accuracy or better. Efficiency and Power Dissipation At high current levels, the I2R losses in R SENSE can be significant. Take this into consideration when choosing the resistor value and its power dissipation (wattage) rating. Also, the sense resistor s value might drift if it is allowed to heat up excessively. The precision V OS of the / MAX9919/MAX992 allows the use of small 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 low inductance value. Power-Supply Bypassing and Grounding Bypass the /MAX9919/MAX992 s V CC to ground with a.1µf capacitor. Grounding these devices requires no special precautions; follow the same cautionary steps that apply to the rest of the system. High-current systems can experience large voltage drops across a ground plane, and this drop may add to or subtract from V OUT. Using a differential measurement between OUT and REFIN prevents this problem. For highest currentmeasurement accuracy, use a single-point star ground. Connect the exposed pad to a solid ground to ensure optimal thermal performance. Maxim Integrated 15

16 /MAX9919/MAX992-2V to +75V Input Range, Functional Diagram V CC MAX9919F A OUT R2 5mV (typ) RS+ R SENSE RS- INPUT INPUT STAGE/ LEVEL SHIFTER R1 FB REFIN I LOAD FIXED GAIN G = 45V/V OR 9V/V SHDN GND V CC MAX992 A OUT R2 5mV (typ) MAX992 2mV (typ) RS+ R SENSE RS- INPUT INPUT STAGE/ LEVEL SHIFTER FB REFIN R1 I LOAD ADJUSTABLE GAIN SHDN GND GAIN IS SET BY EXTERNAL RESISTORS, R1 AND R2 G = [1+(R2/R1)] FOR G = [1+(R2/R1)]/4 FOR MAX992 Chip Information PROCESS: BiCMOS Maxim Integrated 16

17 /MAX9919/MAX992-2V to +75V Input Range, Package Information For the latest package outline information and land patterns (footprints), go to 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. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 SO-EP S8E Maxim Integrated 17

18 /MAX9919/MAX992-2V to +75V Input Range, Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 1/9 Initial release 1 1/1 Updated Functional Diagram /1 Added automotive qualified part 1 3 6/11 Added MAX992ASA/V+ to data sheet 1 4 7/11 Added automotive qualified parts for the MAX9919NASA/V+ and the MAX992ASA/V /13 Added automotive qualified part for the MAX9919FASA/V /15 Updated Applications and Benefits and Features section 1 7 1/17 Added Junction-to-Case Thermal Resistance specification to Package Thermal Characteristics section 2 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim Integrated s website at 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. 217 Maxim Integrated Products, Inc. 18