MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference General Description The MAX4069-MAX4072 low-cost, bidirectional, highside, current-sense amplifiers are ideal for monitoring battery charge and discharge currents in notebooks, cell phones, and other portable equipment. They feature up to 24V input common-mode voltage range, low 100A supply current (which drops to only 10A in shutdown), and a total output error of less than 1.5%. The wide 1.35V to 24V input common-mode range is independent of the supply voltage, ensuring that the current-sense feedback remains accurate even when connected to a battery pack in deep discharge. To achieve maximum flexibility, an external current-sense resistor is used along with a Gain Select pin to choose either 50V/V or 100V/V. A single output pin continuously monitors the transition from charge to discharge and avoids the need for a separate polarity output. The MAX4070 contains an internal 2.5V reference. The charging current is represented by an output voltage from 2.5V to VCC, while discharge current is given from 2.5V to GND. The MAX4071 is similar, but with a reference voltage of 1.5V. The MAX4069 has an adjustable reference voltage, set by two external resistors. The MAX4072 has an input for an external reference. The MAX4069/MAX4071/MAX4072 operate from a 2.7V to 24V single supply. The MAX4070 operates from a 3.6V to 24V single supply. All devices are specified over the automotive operating temperature range, -40C to +125C. The MAX4070/MAX4071/MAX4072 are available in 8-pin MAX and 8-pin thin QFN packages. The MAX4069 is available in a 10-pin MAX(R) package. Applications Notebook Fuel Gauging Smart-Battery Packs/Chargers Motor Control Power-Management Systems Cell-Phone Battery-Current Monitoring Features Bidirectional, Compact, Current-Sense Solution Total Output Error Less than 1.5% Selectable Gain of 50V/V or 100V/V Wide 1.35V to 24V Common-Mode Range Independent of Supply Voltage 2.7V to 24V Single-Supply Operation Internal Precision Reference * Adjustable (MAX4069) * 2.50V (MAX4070) * 1.50V (MAX4071) Low 100A Supply Current 10A Supply Current in Shutdown Available in Space-Saving Packages * 8-Pin Thin QFN (MAX4070/MAX4071/MAX4072) * 8-Pin MAX (MAX4070/MAX4071/MAX4072) * 10-Pin MAX (MAX4069) Ordering Information PIN-PACKAGE TEMP RANGE MAX4069AUB+ -40C to +125C 10 MAX -- MAX4070AUA+ -40C to +125C 8 MAX -- MAX4070ATA+ -40C to +125C 8 Thin QFN-EP* MAX4071AUA+ -40C to +125C 8 MAX MAX4071ATA+ -40C to +125C 8 Thin QFN-EP* MAX4072AUA+ -40C to +125C 8 MAX MAX4072ATA+ -40C to +125C 8 Thin QFN-EP* VBATT = 1.35V TO 24V RS- Pin Configurations and Selector Guide appear at end of data sheet. 19-2423; Rev 4; 11/16 FROM BATTERY CHARGER LOAD RS+ VCC MAX4070 GSEL OUT SHDN REFOUT GND ADI -- Typical Operating Circuit RSENSE ADH -- *EP = Exposed pad. VCC = 3.6V TO 24V MAX is a registered trademark of Maxim Integrated Products, Inc. TOP MARK PART TO ADC 2.5V ADJ MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Absolute Maximum Ratings VCC, RS+, RS- to GND..........................................-0.3V to +26V OUT to GND.................. -0.3V to Lesser of (VCC + 0.3V) or 15V Differential Input Voltage (VRS+ - VRS-)..............................0.3V GSEL, SHDN, REFOUT, REFIN and ADJ to GND.................................... -0.3V to (VCC + 0.3V) OUT Short-Circuit Duration to GND or to Lesser of (VCC or 15V)..................................Continuous REFOUT Short Circuit to VCC or GND......................Continuous Current into Any Pin..........................................................20mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.5mW/C above +70C).............362mW 8-Pin Thin QFN (derate 24.4mW/C above +70C)..... 1951mW 10-Pin MAX (derate 5.6 mW/C above +70C).......444.4mW Operating Temperature Range.......................... -40C to +125C Junction Temperature.......................................................+150C Storage Temperature Range............................. -65C to +150C Lead Temperature (soldering, 10s).................................. +300C 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 (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER Operating Voltage Range (Note 3) SYMBOL VCC CONDITIONS MIN 2.7 24 MAX4070 3.6 24 0.08 Common-Mode Input Range CMVR Guaranteed by CMRR test 1.35 Common-Mode Rejection Ratio CMRR 1.35V VRS+ = VRS- 24V, VCC = 12V 100 ICC VCC = VRS+ = VRS- = 24V, RL = open, TA = TMIN to TMAX ICC SHDN Leakage Current Input Bias Current Recommended Full-Scale Sense Voltage (Note 6) www.maximintegrated.com IRS+, IRSVSENSE VCC = VRS+ = VRS- = 12V TA = +25C VOS Shutdown Supply Current MAX MAX4069/MAX4071/MAX4072 (Note 4) Input-Referred Offset Voltage (Note 5) Supply Current TYP TA = -40C to +85C V 0.25 0.8 TA = TMIN to TMAX UNITS mV 1 24 120 100 V dB 250 A VCC = VRS+ = VRS- = 5.5V, SHDN = GND, TA = +25C 9 VCC = VRS+ = VRS- = 24V, SHDN = GND 10 30 VRS+ = VRS- = 24V, VCC = 0V 0.1 0.5 A 2.4 5 A VCC = VRS+ = VRS- = 24V A 0 Gain = 50V/V 75 Gain = 100V/V 50 mV Maxim Integrated 2 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Electrical Characteristics (continued) (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS VSENSE = 75mV, VCC = VRS+ = 12V, gain = 50 VSENSE = 50mV, VCC = VRS+ = 12V, gain = 100 Total OUT Voltage Error (Note 7) TYP MAX 0.25 1.0 TA = -40C to +85C 1.5 TA = TMIN to TMAX 2.0 TA = +25C 0.25 1.5 TA = TMIN to TMAX 2.5 TA = +25C MAX4069/MAX4070/ MAX4072: VSENSE = -17.5mV, VCC = VRS+ = 12V, gain = 100 TA = +25C MAX4071: VSENSE = -15mV, VCC = VRS+ = 12V, gain = 50 TA = +25C MAX4071: VSENSE = -7.5mV, VCC = VRS+ = 12V, gain = 100 TA = +25C 0.4 1.0 TA = -40C to +85C 2.0 TA = TMIN to TMAX 3.0 0.8 2.0 TA = -40C to +85C 4.0 TA = TMIN to TMAX 6 1.0 4.0 TA = TMIN to TMAX 6.0 5 TA = -40C to +85C 10 TA = TMIN to TMAX 15 TA = +25C % 2.5 TA = -40C to +85C 2.0 UNITS 1.0 TA = -40C to +85C MAX4069/MAX4070/ MAX4072: VSENSE = -35mV, VCC = VRS+ = 12V, gain = 50 VSENSE = 3mV, VCC = 12V, VRS+ = 12V www.maximintegrated.com TA = +25C MIN 3 Maxim Integrated 3 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Electrical Characteristics (continued) (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS IOUT = 10A, VSENSE = 100mV, VRS+ = VCC OUT Voltage High VCC - VOH IOUT = 500A, VSENSE = 100mV, VRS+ = VCC IOUT = -10A, VSENSE = -100mV, VRS+ = VCC OUT Voltage Low VOL IOUT = -500A, VSENSE = -100mV, VRS+ = VCC -3dB Bandwidth BW Gain AV VSENSE = 50mV, VCC = 12V, CL = 100pF MIN TYP MAX MAX4071, VCC = 2.7V 65 150 MAX4069/MAX4070/ MAX4072, VCC = 3.6V 65 150 MAX4071, VCC = 2.7V 90 250 MAX4069/MAX4070/ MAX4072, VCC = 3.6V 90 250 MAX4071, VCC = 2.7V 5 20 MAX4069/MAX4070/ MAX4072, VCC = 3.6V 5 20 MAX4071, VCC = 2.7V 100 250 MAX4069/MAX4070/ MAX4072, VCC = 3.6V 100 250 Gain = 50V/V 100 Gain = 100V/V 40 mV mV GSEL = GND 50 GSEL = VCC 100 Capacitive-Load Stability Power-Supply Rejection Ratio PSRR VCC = 2.7V to 24V (MAX4069/MAX4071/MAX4072), VCC = 3.6V to 24V (MAX4070) Logic Low Voltage (GSEL, SHDN) VIL VCC = 3.6V or 24V Logic High Voltage (GSEL, SHDN) VIH VCC = 3.6V or 24V Gain-Select Input Current IGSEL Shutdown Input Current ISHDN www.maximintegrated.com GSEL = VCC = 24V or GND SHDN = VCC = 24V SHDN = GND, VCC = 24V UNITS 100 kHz V/V 100 pF 120 dB 0.6 2 V V 0.01 1 3 12 0.01 1 A A Maxim Integrated 4 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Electrical Characteristics (continued) (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 2.49 2.54 UNITS REFOUT (MAX4069/MAX4070/MAX4071) Reference Output Voltage Reference Output Voltage Temperature Coefficient VREF TCVREF Load Regulation VREFOUT /IREF Line Regulation VREF/ VCC MAX4069, VCC = 12V (Note 2) TA = +25C 2.44 TA = TMIN to TMAX 2.39 MAX4070, VCC = 12V TA = +25C 2.45 TA = TMIN to TMAX 2.40 MAX4071, VCC = 12V TA = +25C 1.47 TA = TMIN to TMAX 1.44 VCC = 12V VADJ Reference Output Voltage Range Reference Adjust Input Current IADJ 2.5 2.55 V 2.60 1.5 1.53 1.56 -40C TA +85C 15 TA = TMIN to TMAX 20 ppm/C IREFOUT = 0 to 500A 2 IREFOUT = 0 to -100A 4 2.7V VCC 24V 20 V/V 500 pF MAX4069, VCC = 12V 1.230 V MAX4069, range adjustable with R1 and R2, VCC = 12V VADJ to +4 V 100 nA REF Capacitive-Load Stability Reference Adjust Voltage Threshold 2.59 MAX4069, VCC = 12V, VADJ = 1.23V mV/mA REFIN (MAX4072 ONLY) Input-Voltage Range VCC = 12V Input Current REFIN = 2.5V, VCC = 12V Note Note Note Note 1 4 V -60 +20 A 1: 2: 3: 4: All devices are 100% tested at TA = +25C. Limits over temperature are guaranteed by design. R1 = 215k, R2 = 210k for the MAX4069 only (see Functional Diagram). This sets REFOUT to 2.49V nominal. Guaranteed by the PSRR test. The REFOUT voltage for the MAX4069 should be set such that it does not exceed VCC - 1.1V. Similarly, the maximum REFIN voltage for the MAX4072 should also be less than VCC - 1.1V. Note 5: Input-Referred Offset Voltage is defined as the voltage difference between OUT and REFOUT, divided by the selected gain of either 50 or 100, when VSENSE = VRS+ - VRS- = 0V. Note 6: The negative full-scale sense voltage is limited by the voltage range of OUT from VREFOUT to GND. Note 7: Total OUT Voltage Error is the sum of offset voltage and gain errors. The output voltage is measured relative to the reference (REFOUT or REFIN). www.maximintegrated.com Maxim Integrated 5 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Typical Operating Characteristics (VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25C, unless otherwise noted.) 15 10 5 0 -25 -50 -75 -100 -125 -150 -80 -40 0 40 80 120 160 200 -200 -160 -120 0 -50 -25 0 TOTAL ERROR vs. SUPPLY VOLTAGE 0.2 0.1 0 -0.1 VSENSE = 50mV AV = 100V/V -0.2 -0.3 AV = 100V/V 0 -0.5 -2.0 10 12 14 16 18 20 22 24 MAX4069-72 toc03 VSENSE = 50mV AV = 100V/V 1.0 VCC = 24V 0.5 0 VCC = 12V -0.5 -1.0 AV = 50V/V 2 6 10 14 18 -1.5 22 -25 -50 0 25 50 75 100 TEMPERATURE (C) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE MAX4069 REFOUT vs. TEMPERATURE MAX4070 100 MAX4069 90 MAX4072 80 AV = 50V/V 160 140 2 4 6 8 10 12 14 16 18 20 22 24 VCC = 24V 120 100 VCC = 12V 80 SUPPLY VOLTAGE (V) www.maximintegrated.com 40 REFOUT CONNECTED TO ADJ 1.240 1.235 1.230 1.225 1.220 1.215 1.210 60 70 1.245 REFOUT (V) 110 1.250 MAX4069-72 toc08 MAX4071 180 SUPPLY CURRENT (A) AV = 100V/V 125 MAX4069-72 toc09 SUPPLY VOLTAGE (V) 120 60 0.5 TOTAL ERROR vs. TEMPERATURE 1.5 SUPPLY VOLTAGE (V) 130 SUPPLY CURRENT (A) 8 MAX4069-72 toc07 140 6 25 50 75 100 125 150 175 200 225 250 0 VSENSE (V) 1.0 -1.5 4 AV = 50V/V -1.0 -0.4 -0.5 125 MAX4069-72 toc05 VSENSE = 75mV AV = 50V/V 100 1.5 TOTAL ERROR (%) TOTAL ERROR (%) 0.3 75 TOTAL ERROR vs. SUPPLY VOLTAGE (VSENSE = 3mV) 2.0 MAX4069-72 toc04 0.4 50 7 6 5 4 3 2 1 0 AV = 100V/V TEMPERATURE (C) VOS (V) 0.5 25 10 9 8 MAX4069-72 toc06 20 75 50 25 (VOUT - VREF) (V) 25 AV = 100V/V 125 100 (VOUT - VREF) vs. VSENSE 12 11 TOTAL ERROR (%) 30 150 INPUT OFFSET VOLTAGE (V) MAX4069-72 toc01 PERCENTAGE OF UNITS (%) 35 INPUT OFFSET VOLTAGE vs. TEMPERATURE MAX4069-72 toc02 INPUT OFFSET VOLTAGE DISTRIBUTION 1.205 -50 -25 0 25 50 75 TEMPERATURE (C) 100 125 1.200 -50 -25 0 25 50 75 100 125 TEMPERATURE (C) Maxim Integrated 6 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Typical Operating Characteristics (continued) (VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25C, unless otherwise noted.) 1.515 2.480 2.465 -25 0 25 50 75 100 1.500 1.495 1.219 1.480 1.217 -50 -25 0 25 50 75 100 1.501 1.500 4 6 1.495 8 10 12 14 16 18 20 22 24 2 6 10 14 18 0 22 SMALL-SIGNAL GAIN vs. FREQUENCY 0 175 GAIN (dB) IL = 500A 125 100 AV = 50V/V -5 -10 AV = 100V/V 75 -15 IL = 10A 25 -50 -25 0 25 50 75 TEMPERATURE (C) www.maximintegrated.com -50 100 125 -20 -25 0 25 50 75 100 125 TEMPERATURE (C) MAX4069-72 toc17 200 50 IL = 10A 20 5 MAX4069-72 toc16 225 150 80 SUPPLY VOLTAGE (V) VOL vs. TEMPERATURE 250 100 40 PSRR AND CMRR vs. FREQUENCY 0 -20 PSRR AND CMRR (dB) 2 IL = 500A 120 60 SUPPLY VOLTAGE (V) VOL (mV) 160 1.496 2.491 VOH = VCC - VOUT 180 1.497 2.492 8 10 12 14 16 18 20 22 24 VOH vs. TEMPERATURE 200 VOH (mV) REFOUT (V) 2.493 6 140 1.498 2.494 4 2 SUPPLY VOLTAGE (V) MAX4069-72 toc14 MAX4069-72 toc13 1.502 1.215 125 1.499 2.495 1.223 1.221 MAX4071 REFOUT vs. SUPPLY VOLTAGE 2.496 1.225 1.485 MAX4070 REFOUT vs. SUPPLY VOLTAGE 2.497 1.227 1.490 TEMPERATURE (C) 2.498 REFOUT (V) 1.505 1.475 125 1.229 TEMPERATURE (C) 2.499 0 1.231 MAX4069-72 toc18 -50 2.500 2.490 1.233 REFOUT (V) REFOUT (V) 2.495 MAX4069-72 toc12 1.520 1.510 2.510 2.450 1.235 MAX4069-72 toc11 2.525 REFOUT (V) 1.525 MAX4069-72 toc10 2.540 MAX4069 REFOUT vs. SUPPLY VOLTAGE MAX4071 REFOUT vs. TEMPERATURE MAX4069-72 toc15 MAX4070 REFOUT vs. TEMPERATURE -40 CMRR -60 -80 -100 PSRR -120 0.1 1 10 FREQUENCY (kHz) 100 1000 -140 0.01 0.1 1 10 100 FREQUENCY (Hz) Maxim Integrated 7 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Typical Operating Characteristics (continued) (VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25C, unless otherwise noted.) SMALL-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL TRANSIENT RESPONSE MAX4069-72 toc19 LARGE-SIGNAL TRANSIENT RESPONSE MAX4069-72 toc20 MAX4069-72 toc21 GAIN = 100 GAIN = 50 GAIN = 50 INPUT 5mV/div INPUT 5mV/div OUTPUT 200mV/div OUTPUT 500mV/div REF REF 100s/div 100s/div LARGE-SIGNAL TRANSIENT RESPONSE STARTUP DELAY MAX4069-72 toc22 INPUT 50mV/div OUTPUT 2V/div REF 100s/div EXITING SHUTDOWN MAX4069-72 toc23 MAX4069-72 toc24 GAIN = 100 INPUT 20mV/div OUTPUT 2V/div VCC 10V/div VSHDN 5V/div VOUT 5V/div VOUT 2V/div VREFOUT 5V/div VREFOUT 2V/div REF 100s/div www.maximintegrated.com 20s/div 100s/div Maxim Integrated 8 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Pin Description PIN NAME FUNCTION MAX4069 MAX4070/ MAX4071 MAX4072 1 1 1 SHDN 2 2 2 RS- Negative Connection to the External Sense Resistor 3 3 3 RS+ Positive Connection to the External Sense Resistor 4 -- -- N.C. No Connection. Not internally connected. 5 4 4 GND Ground. For thin QFN packages, also make an external connection from GND to the under-side exposed paddle. 6 -- -- ADJ Adjustable Output Voltage Feedback Input. Connect a resistor-divider between REFOUT, ADJ, and GND (MAX4069 only, see Functional Diagram). 7 5 -- REFOUT 8 6 6 OUT Voltage Output. The difference voltage, VOUT - VREF, is proportional to the voltage difference between RS+ and RS- and indicates the correct polarity. 9 7 7 VCC Supply Voltage Input. Bypass VCC to GND with a 0.1F capacitor. 10 8 8 GSEL Gain-Setting Input. Connect GSEL low to select gain = 50V/V, or connect GSEL high to select gain = 100V/V. -- -- 5 REFIN Reference Input Voltage (MAX4072) Shutdown Input. Drive SHDN low to select shutdown mode. Connect SHDN to VCC for normal operation. Reference Output Voltage (MAX4069/MAX4070/MAX4071) Functional Diagram 2.7V TO 24V LOAD FROM BATTERY CHARGER VCC RS+ MAX4069 OUT CSA RSENSE TO ADC RSGAIN SELECT SHUTDOWN GSEL OA SHDN VREF 1.23V GND www.maximintegrated.com REFOUT R1 ADJ R2 Maxim Integrated 9 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Detailed Description RSENSE The MAX4069-MAX4072 bidirectional, high-side, current-sense amplifiers are ideal for portable equipment. The wide 1.35V to 24V input common-mode voltage range is independent of the supply voltage, ensuring that the current-sense feedback remains accurate even when connected to a battery pack in deep discharge. The MAX4069/MAX4071/MAX4072 operate from a 2.7V to 24V single supply. Because the MAX4070 has a 2.5V internal reference, it operates from 3.6V to 24V. All devices have a low 100A supply current that reduces to only 10A (typ) in shutdown mode. To achieve maximum flexibility, an external current-sense resistor is used along with a gain select pin (GSEL) to choose either 50V/V or 100V/V. Drive GSEL low to select gain of 50V/V or drive GSEL high to choose gain of 100V/V (see Functional Diagram). The MAX4069 has an adjustable reference voltage set by two external resistors between REFOUT and ADJ, and GND pins. The MAX4070 contains an internal 2.5V reference. The MAX4071 is similar to the MAX4070 but with a fixed internal reference voltage of 1.5V. The MAX4072 has a reference input pin to allow use of external references. Charging current is represented by an output voltage from the reference voltage to VCC, while discharge current is given from the reference voltage to GND. The direction of VSENSE is totally arbitrary. The input stage of the MAX4069-MAX4072 is shown in Figure 1. Its unique topology allows for monitoring bidirectional currents through the sense resistor (RSENSE). If, for instance, current flows from RS+ to RS-, the MAX4069-MAX4072 match for the voltage drop over the external sense resistor(RSENSE) by increasing the current through the internal Q1 and RG1. At the same time, the current through Q2 and RG2 decreases, however, internal circuitry not shown in Figure 1 prevents Q2 from turning off completely. Likewise, if current flows from RSto RS+, the current through Q2 and RG2 increases and the current through Q1 decreases. In this way, the voltages at the input terminals of the internal amplifier A1 are kept constant and an accurate measurement of the sense voltage is achieved. In the following amplifier stages of the MAX4069-MAX4072, the output signal of amplifier A2 is level-shifted towards the reference voltage (VREF), resulting in a voltage at the output pin (OUT) that swings above the VREF voltage for positive-sense voltages and below VREF for negative-sense voltages. Note: RG1 = RG2 = 104k (typ). www.maximintegrated.com RS+ RS- RG1 RG2 MAX4069-MAX4072 OUT A1 Q1 A2 Q2 IOUT Figure 1. Detailed Input Stage Applications Information Bidirectional, Current-Sense Amplifier Systems such as laptop computers and other devices that have internal charge circuitry require a precise bidirectional, current-sense amplifier to accurately monitor the battery's current regardless of polarity. Figure 2 shows the MAX4069-MAX4072 used as a bidirectional current monitor. In Figure 2, the direction of VSENSE is assigned to charge and discharge, assuming charge is greater than discharge. The practical choice of direction is based on dynamic range at OUT, given that the range of REF to VCC is usually greater than from REF to ground. This is useful for implementing either smart battery packs or fuel gauges. High-Current Measurement The MAX4069-MAX4072 can achieve high-current measurements by using low-value sense resistors, which can be paralleled to further increase the current-sense limit. Adjusting VREF (MAX4069) The MAX4069 has an output reference voltage that can be set to a desired voltage by a two-resistor divider between REFOUT, ADJ, and GND. If REFOUT and ADJ are connected together, the minimum output reference voltage is obtained, 1.23V (typ). The maximum voltage for REFOUT is 4V (that requires VCC 5.1V). The recommended range for the external resistors is: R1 + R2 should be > 20k and < 500k. Maxim Integrated 10 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference RS- 2 CELLS ICHARGE RSENSE IDISCHARGE 5V RS+ AV = 100 VOUT - VREF LOAD CHARGE CURRENT 2.5V VCC MAX4070 GSEL OUT TO ADC -25mV SHDN REFOUT 2.5V GND 0 DISCHARGE CURRENT 25mV VSENSE 50mV -2.5V Figure 2. Bidirectional Current Monitor External Reference (MAX4072) The MAX4069-MAX4072 sense a wide variety of currents with different sense-resistor values. Table 1 lists common resistor values for typical operation of these devices. Listed output voltage is with respect to REF. Reference Output (MAX4069/MAX4060/MAX4071) Sense Resistor, RSENSE Recommended Component Values Accuracy: A high RSENSE value allows lower currents to be measured more accurately. This is because offsets become less significant when the sense voltage is larger. For best performance, select RSENSE to provide approximately 75mV (gain of 50V/V) or 50mV (gain of 100V/V) of sense voltage for the full-scale current in each application. The MAX4072 contains REFIN pin for external reference voltage. The allowable voltage range on REFIN is 1V (min) to 4V (max) with VCC 5.1V. The REFOUT of the MAX4069/MAX4070/MAX4071 can sink 100A and source 500A. Keep the total capacitance on REFOUT under 500pF to maintain stability. 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: VOUT = VSENSE x AV where VSENSE is the full-scale sense voltage, 75mV for gain of 50V/V, or 50mV for gain of 100V/V. AV is the gain of the device. In applications monitoring high current, ensure that RSENSE is able to dissipate its own I2R loss. If the resistor's power dissipation is exceeded, its value may drift or it may fail altogether, causing a differential voltage across the terminals in excess of the absolute maximum ratings. Use resistors specified for current-sensing applications. www.maximintegrated.com Choose RSENSE based on the following criteria: Voltage Loss: A high RSENSE value causes the powersource voltage to degrade through IR loss. For minimal voltage loss, use the lowest RSENSE value. Efficiency and Power Dissipation: At high-current levels, the I2R losses in RSENSE 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. Inductance: Keep inductance low if ISENSE has a large high-frequency component. Wire-wound resistors have the highest inductance, while metal film is somewhat better. Low-inductance metal-film resistors are also available. Instead of being spiral-wrapped round a Maxim Integrated 11 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Table 1. Recommended Component Values FULL-SCALE CURRENT (A) 0.075 0.05 0.75 0.5 3.75 2.5 7.5 5.0 15.0 10.0 CURRENT-SENSE RESISTOR (m) 1000 100 20 10 5 core, as in metal-film or wire-wound resistors, they are a straight band of metal and are available in values under 1. Peak Current: The maximum current through RSENSE must be limited to: IPEAK = 0.3V / (RSENSE + RTRACE) where RTRACE is the total stray resistance from RS+ and RS- to RSENSE. To prevent forwarding the back-to-back diodes between the differential input, the absolute maximum of the differential input voltage is 0.3V. Dynamic Range Considerations Although the MAX4069-MAX4072 have fully symmetrical, bidirectional, VSENSE input capability, the output-voltage range is usually higher from REF to VCC and lower from REF to GND (unless the supply voltage is at the lowest end of the operating range). Therefore, the user must consider the dynamic range of current monitored in both directions and choose the supply voltage and the reference voltage (REFOUT or REFIN) to make sure the output swing above and below REF is adequate to handle the swings without clipping or running out of headroom. GAIN (V/V) VSENSE (mV) FULL-SCALE OUTPUT VOLTAGE WITH RESPECT TO REF (V) 50 75 3.75 100 50 5.0 50 75 3.75 100 50 5.0 50 75 3.75 100 50 5.0 50 75 3.75 100 50 5.0 50 75 3.75 100 50 5.0 Power-Supply Bypassing and Grounding The MAX4069-MAX4072 do not require special bypassing and respond quickly to transient changes in line current. You can place a large capacitor at the RS- terminal (or "load" side) to decouple the load and, thereby, reduce the current transients. These capacitors are not required for operation or stability and their use does not degrade performance. The MAX4069-MAX4072 have been designed as a highside current monitor to ease the task of grounding any battery charger, thermistor, etc., that may be a part of the battery pack. Grounding these devices requires no special precautions; follow the same cautionary steps that apply to the system as a whole. High-current systems can experience large voltage drops across a ground plane, and this drop may add to or subtract from VOUT. Using differential measurement between VOUT and REF prevents this problem. For highest current-measurement accuracy, use a single-point star ground. On thin QFN packages, there is an exposed paddle that does not carry any current, but should also be connected to the ground plane for rated power dissipation. Shutdown Mode When SHDN is low, the MAX4069-MAX4072 are shut down and consume only 10A. In shutdown mode, OUT is high impedance and turns off. Connect SHDN to VCC for normal operation. www.maximintegrated.com Maxim Integrated 12 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Pin Configurations TOP VIEW SHDN 1 RS- 2 RS+ 3 N.C. GND + SHDN 1 10 GSEL 9 VCC 8 OUT 4 7 REFOUT 5 6 ADJ MAX4069 RS- 2 RS+ 3 + MAX4070 MAX4071 MAX4072 GND 4 MAX 8 GSEL 7 VCC 6 OUT 5 REFOUT (REFIN) Thin QFN/MAX (REFIN) FOR MAX4072 ONLY. Selector Guide Layout In order to dissipate sense-resistor heat from large sense currents, solder the RS+ and the RS- pins to large copper traces. Keep the part away from other heat-generating devices. For accurate measurement of VSENSE, the Kelvin method is recommended. The current into RS+ and RS- is only a few microamps; therefore, a short distance from RS+ and RS- pins does not cause significant errors. It is recommended to keep the value of RSENSE reasonably higher than the values of the trace's resistance. PART REFERENCE SUPPLY VOLTAGE RANGE (V) COMMONMODE RANGE (V) MAX4069 ADJUSTABLE 2.7 to 24 1.35 to 24 MAX4070 2.5V 3.6 to 24 1.35 to 24 MAX4071 1.5V 2.7 to 24 1.35 to 24 MAX4072 EXTERNAL 2.7 to 24 1.35 to 24 Chip Information TRANSISTOR COUNT: 338 PROCESS: BiCMOS 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. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TQFN-EP T833-2 21-0137 8 MAX U8-1 21-0036 10 MAX U10-2 21-0061 www.maximintegrated.com Maxim Integrated 13 MAX4069-MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Revision History REVISION NUMBER REVISION DATE 3 11/08 Added information for RG1 and RG2 10 4 11/16 Updated Ordering Information table 1 DESCRIPTION PAGES CHANGED For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated's website at www.maximintegrated.com. 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. (c) 2016 Maxim Integrated Products, Inc. 14