19-2423; Rev 3; 11/08 Bidirectional, High-Side, Current-Sense Amplifiers with Reference 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 100µA supply current (which drops to only 10µA 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, -40°C to +125°C. The MAX4070/MAX4071/MAX4072 are available in 8-pin µMAX and 8-pin thin QFN packages. The MAX4069 is available in a 10-pin µMAX® package. Applications Notebook Fuel Gauging 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 100µA Supply Current ♦ 10µA Supply Current in Shutdown ♦ Available in Space-Saving Packages 8-Pin Thin QFN (MAX4070/MAX4071/MAX4072) 8-Pin µMAX (MAX4070/MAX4071MAX4072) 10-Pin µMAX (MAX4069) Ordering Information PART TEMP RANGE PIN-PACKAGE MAX4069AUB -40°C to +125°C 10 µMAX MAX4070AUA -40°C to +125°C 8 µMAX MAX4070ATA -40°C to +125°C 8 Thin QFN-EP* MAX4071AUA -40°C to +125°C 8 µMAX MAX4071ATA -40°C to +125°C 8 Thin QFN-EP* MAX4072AUA -40°C to +125°C 8 µMAX ABN — ABO — ABP Typical Operating Circuit Motor Control FROM BATTERY CHARGER Power-Management Systems Cell-Phone Battery-Current Monitoring — MAX4072ATA -40°C to +125°C 8 Thin QFN-EP* *EP = Exposed pad. Smart-Battery Packs/Chargers TOP MARK — RSENSE VBATT = 1.35V TO 24V RS- VCC = 3.6V TO 24V RS+ LOAD VCC MAX4070 GSEL µMAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configurations and Selector Guide appear at end of data sheet. OUT SHDN REFOUT TO ADC 2.5V GND ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX4069–MAX4072 General Description 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 = +70°C) 8-Pin µMAX (derate 4.5 mW/°C above +70°C) ............362mW 8-Pin Thin QFN (derate 24.4mW/°C above +70°C) ...1951mW 10-Pin µMAX (derate 5.6 mW/°C above +70°C) .......444.4mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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, V SHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN 24 MAX4070 3.6 24 VCC Input-Referred Offset Voltage (Note 5) VOS 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 Shutdown Supply Current ICC SHDN Leakage Current Input Bias Current Recommended Full-Scale Sense Voltage (Note 6) 2 VCC = VRS+ = VRS- = 12V TA = +25°C 0.08 TA = -40°C to +85°C TA = TMIN to TMAX VSENSE UNITS V 0.25 0.8 mV 1 24 120 100 V dB 250 µA VCC = VRS+ = VRS- = 5.5V, SHDN = GND, TA = +25°C 9 VCC = VRS+ = VRS- = 24V, SHDN = GND 10 30 0.1 0.5 µA 2.4 5 µA µA VRS+ = VRS- = 24V, VCC = 0V IRS+, IRS- MAX 2.7 Operating Voltage Range (Note 3) Supply Current TYP MAX4069/MAX4071/MAX4072 (Note 4) VCC = VRS+ = VRS- = 24V 0 Gain = 50V/V 75 Gain = 100V/V 50 _______________________________________________________________________________________ mV Bidirectional, High-Side, Current-Sense Amplifiers with Reference (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER Total OUT Voltage Error (Note 7) SYMBOL CONDITIONS VSENSE = 75mV, VCC = VRS+ = 12V, gain = 50 TA = +25°C VSENSE = 50mV, VCC = VRS+ = 12V, gain = 100 TA = +25°C MAX4069/MAX4070/ MAX4072: VSENSE = -35mV, VCC = VRS+ = 12V, gain = 50 TA = +25°C MAX4069/MAX4070/ MAX4072: VSENSE = -17.5mV, VCC = VRS+ = 12V, gain = 100 TA = +25°C MAX4071: VSENSE = -15mV, VCC = VRS+ = 12V, gain = 50 TA = +25°C MAX4071: VSENSE = -7.5mV, VCC = VRS+ = 12V, gain = 100 TA = +25°C VSENSE = 3mV, VCC = 12V, VRS+ = 12V MIN TYP MAX ±0.25 ±1.0 TA = -40°C to +85°C ±1.5 TA = TMIN to TMAX ±2.0 ±0.25 ±1.0 TA = -40°C to +85°C ±1.5 TA = TMIN to TMAX ±2.5 ±0.4 ±1.0 TA = -40°C to +85°C ±2.0 TA = TMIN to TMAX ±3.0 ±0.8 ±2.0 TA = -40°C to +85°C ±4.0 TA = TMIN to TMAX ±6 ±1.0 ±4.0 TA = TMIN to TMAX ±6.0 ±5 TA = -40°C to +85°C ±10 TA = TMIN to TMAX ±15 TA = +25°C % ±2.5 TA = -40°C to +85°C ±2.0 UNITS ±3 _______________________________________________________________________________________ 3 MAX4069–MAX4072 ELECTRICAL CHARACTERISTICS (continued) 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, V SHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS IOUT = 10µA, VSENSE = 100mV, VRS+ = VCC OUT Voltage High IOUT = -10µA, VSENSE = -100mV, VRS+ = VCC IOUT = -500µA, VSENSE = -100mV, VRS+ = VCC BW Gain AV 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 VSENSE = 50mV, VCC = 12V, CL = 100pF Gain = 100V/V 100 GSEL = GND 50 GSEL = VCC 100 Logic Low Voltage (GSEL, SHDN) Logic High Voltage (GSEL, SHDN) PSRR VIL VCC = 3.6V or 24V VIH VCC = 3.6V or 24V Gain-Select Input Current IGSEL Shutdown Input Current ISHDN 4 VCC = 2.7V to 24V (MAX4069/MAX4071/MAX4072), VCC = 3.6V to 24V (MAX4070) GSEL = VCC = 24V or GND SHDN = VCC = 24V SHDN = GND, VCC = 24V kHz 40 Capacitive-Load Stability Power-Supply Rejection Ratio UNITS mV VOL -3dB Bandwidth TYP mV VCC - VOH IOUT = 500µA, VSENSE = 100mV, VRS+ = VCC OUT Voltage Low MIN 100 V/V 100 pF 120 dB 0.6 V 0.01 1 µA 3 12 0.01 1 2 V _______________________________________________________________________________________ µA Bidirectional, High-Side, Current-Sense Amplifiers with Reference (VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = VCC, VGSEL = GND, VREFIN = 2.5V (MAX4072), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C and at VCC = VRS+ = 12V.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX TA = +25°C 2.44 2.49 2.54 TA = TMIN to TMAX 2.39 UNITS REFOUT (MAX4069/MAX4070/MAX4071) MAX4069, VCC = 12V (Note 2) Reference Output Voltage Reference Output Voltage Temperature Coefficient VREF TCVREF Load Regulation ΔVREFOUT /ΔIREF Line Regulation ΔVREF/ ΔVCC MAX4070, VCC = 12V TA = +25°C 2.45 TA = TMIN to TMAX 2.40 MAX4071, VCC = 12V TA = +25°C 1.47 TA = TMIN to TMAX 1.44 VCC = 12V VADJ Reference Adjust Input Current IADJ 2.55 V 2.60 1.5 1.53 1.56 -40°C ≤ TA ≤ +85°C 15 20 ppm/°C IREFOUT = 0 to 500µA 2 IREFOUT = 0 to -100µA 4 2.7V ≤ VCC ≤ 24V 20 µV/V 500 pF 1.230 V VADJ to +4 V 100 nA MAX4069, VCC = 12V MAX4069, range adjustable with R1 and R2, VCC = 12V Reference Output Voltage Range 2.5 TA = TMIN to TMAX 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 1 4 V -60 +20 µA All devices are 100% tested at TA = +25°C. Limits over temperature are guaranteed by design. R1 = 215kΩ, R2 = 210kΩ 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). Note 1: Note 2: Note 3: Note 4: _______________________________________________________________________________________ 5 MAX4069–MAX4072 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.) INPUT OFFSET VOLTAGE vs. TEMPERATURE 15 10 0 -25 -50 5 -75 -100 0 -125 -150 -50 -25 0 0.1 0 -0.1 VSENSE = 50mV AV = 100V/V -0.2 -0.3 75 100 125 0 TOTAL ERROR vs. TEMPERATURE 1.5 MAX4069-72 toc05 1.0 0.5 AV = 100V/V 0 -0.5 1.0 0 VCC = 12V -0.5 -1.0 -1.5 2 10 12 14 16 18 20 22 24 8 VCC = 24V 0.5 AV = 50V/V -2.0 -0.5 6 VSENSE = 50mV AV = 100V/V -1.0 -1.5 4 25 50 75 100 125 150 175 200 225 250 VSENSE (V) 1.5 -0.4 6 10 14 18 22 -50 -25 0 25 50 75 100 SUPPLY VOLTAGE (V) TEMPERATURE (°C) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE MAX4069 REFOUT vs. TEMPERATURE 110 MAX4070 100 MAX4069 90 MAX4072 80 160 1.245 REFOUT CONNECTED TO ADJ 1.240 140 125 MAX4069-72 toc09 120 AV = 50V/V 1.235 REFOUT (V) MAX4071 1.250 MAX4069-72 toc08 130 180 SUPPLY CURRENT (μA) AV = 100V/V MAX4069-72 toc07 SUPPLY VOLTAGE (V) 140 VCC = 24V 120 100 VCC = 12V 80 1.230 1.225 1.220 1.215 1.210 70 60 60 40 2 4 6 8 10 12 14 16 18 20 22 24 SUPPLY VOLTAGE (V) 6 50 TOTAL ERROR (%) 0.2 25 2.0 MAX4069-72 toc04 VSENSE = 75mV AV = 50V/V AV = 50V/V TOTAL ERROR vs. SUPPLY VOLTAGE (VSENSE = 3mV) TOTAL ERROR (%) TOTAL ERROR (%) 0.3 4 3 TEMPERATURE (°C) TOTAL ERROR vs. SUPPLY VOLTAGE 0.4 AV = 100V/V 8 7 6 5 2 1 0 VOS (μV) 0.5 10 9 MAX4069-72 toc03 75 50 25 MAX4069-72 toc06 20 AV = 100V/V 125 100 12 11 (VOUT - VREF) (V) 25 -200 -160 -120 -80 -40 0 40 80 120 160 200 PERCENTAGE OF UNITS (%) 30 (VOUT - VREF) vs. VSENSE 150 INPUT OFFSET VOLTAGE (μV) MAX4069-72 toc01 35 MAX4069-72 toc02 INPUT OFFSET VOLTAGE DISTRIBUTION SUPPLY CURRENT (μA) MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference 1.205 1.200 -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 -50 -25 0 25 50 75 TEMPERATURE (°C) _______________________________________________________________________________________ 100 125 Bidirectional, High-Side, Current-Sense Amplifiers with Reference MAX4070 REFOUT vs. TEMPERATURE 1.515 1.233 1.231 1.229 2.465 2.450 1.505 1.500 1.495 -25 0 25 50 75 100 1.485 1.219 1.480 1.217 125 1.215 -50 -25 0 25 50 75 100 MAX4070 REFOUT vs. SUPPLY VOLTAGE MAX4071 REFOUT vs. SUPPLY VOLTAGE 1.501 2.496 2.495 2.494 2.493 8 10 12 14 16 18 20 22 24 160 1.500 140 1.499 120 1.498 VOH = VCC - VOUT 180 IL = 500μA 100 80 60 1.497 2.492 40 1.496 1.495 2.490 6 0 2 8 10 12 14 16 18 20 22 24 6 10 14 18 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) VOL vs. TEMPERATURE SMALL-SIGNAL GAIN vs. FREQUENCY 5 MAX4069-72 toc16 250 225 200 22 -50 0 GAIN (dB) 150 IL = 500μA 125 100 AV = 50V/V -10 AV = 100V/V 75 0 25 50 75 125 100 PSRR AND CMRR vs. FREQUENCY 175 -5 -25 TEMPERATURE (°C) 0 -20 PSRR AND CMRR (dB) 4 MAX4069-72 toc17 2 IL = 10μA 20 MAX4069-72 toc18 2.491 VOL (mV) 6 VOH vs. TEMPERATURE VOH (mV) REFOUT (V) 2.497 4 200 MAX4069-72 toc14 1.502 MAX4069-72 toc13 2.498 2 125 SUPPLY VOLTAGE (V) TEMPERATURE (°C) 2.499 1.223 1.221 TEMPERATURE (°C) 2.500 1.225 1.490 1.475 -50 1.227 MAX4069-72 toc15 2.495 REFOUT (V) REFOUT (V) 2.510 MAX4069-72 toc12 1.520 1.510 2.480 REFOUT (V) 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 -40 CMRR -60 -80 -100 PSRR -15 50 -120 IL = 10μA 25 -20 0 -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 -140 0.1 1 10 FREQUENCY (kHz) 100 1000 0.01 0.1 1 10 100 FREQUENCY (Hz) _______________________________________________________________________________________ 7 MAX4069–MAX4072 Typical Operating Characteristics (continued) (VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.) 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 = +25°C, unless otherwise noted.) SMALL-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL TRANSIENT RESPONSE LARGE-SIGNAL TRANSIENT RESPONSE MAX4069-72 toc20 MAX4069-72 toc21 MAX4069-72 toc19 GAIN = 100 GAIN = 50 GAIN = 50 INPUT 5mV/div INPUT 5mV/div OUTPUT 200mV/div OUTPUT 500mV/div REF REF 100μs/div 100μs/div OUTPUT 2V/div REF 100μs/div STARTUP DELAY LARGE-SIGNAL TRANSIENT RESPONSE INPUT 50mV/div EXITING SHUTDOWN MAX4069-72 toc23 MAX4069-72 toc22 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 100μs/div 8 20μs/div 100μs/div _______________________________________________________________________________________ Bidirectional, High-Side, Current-Sense Amplifiers with Reference PIN NAME FUNCTION MAX4069 MAX4070/ MAX4071 MAX4072 1 1 1 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. Shutdown Input. Drive SHDN low to select shutdown mode. Connect SHDN to VCC for normal operation. SHDN 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 — 8 6 6 OUT 9 7 7 VCC REFOUT Reference Output Voltage (MAX4069/MAX4070/MAX4071) Voltage Output. The difference voltage, VOUT - VREF, is proportional to the voltage difference between RS+ and RS- and indicates the correct polarity. Supply Voltage Input. Bypass VCC to GND with a 0.1µF 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) 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 REFOUT R1 ADJ GND R2 _______________________________________________________________________________________ 9 MAX4069–MAX4072 Pin Description MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Detailed Description 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 100µA supply current that reduces to only 10µA (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). 10 RSENSE RS+ RS- RG1 RG2 MAX4069–MAX4072 OUT A1 Q1 Q2 A2 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 V CC 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 currentsense 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 > 20kΩ and < 500kΩ. ______________________________________________________________________________________ Bidirectional, High-Side, Current-Sense Amplifiers with Reference RS- 5V AV = 100 VOUT - VREF RS+ LOAD CHARGE CURRENT 2.5V VCC 2 CELLS MAX4069–MAX4072 ICHARGE RSENSE IDISCHARGE MAX4070 GSEL OUT TO ADC -25mV 0 25mV 50mV VSENSE SHDN REFOUT 2.5V GND DISCHARGE CURRENT -2.5V Figure 2. Bidirectional Current Monitor External Reference (MAX4072) 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. Reference Output (MAX4069/MAX4060/MAX4071) The REFOUT of the MAX4069/MAX4070/MAX4071 can sink 100µA and source 500µA. Keep the total capacitance on REFOUT under 500pF to maintain stability. Recommended Component Values Ideally, the maximum load current develops the fullscale 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. 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. Sense Resistor, RSENSE 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. 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. 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 ______________________________________________________________________________________ 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 (mΩ) 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 1Ω. 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-toback 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 outputvoltage 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 3.75 50 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 RSterminal (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 10µA. In shutdown mode, OUT is high impedance and turns off. Connect SHDN to VCC for normal operation. 12 ______________________________________________________________________________________ Bidirectional, High-Side, Current-Sense Amplifiers with Reference TOP VIEW SHDN 1 RS- 2 RS+ 3 N.C. GND 10 GSEL 9 VCC 8 OUT 4 7 REFOUT 5 6 ADJ MAX4069 SHDN 1 RS- 2 RS+ 3 MAX4070 MAX4071 MAX4072 GND 4 μMAX 8 GSEL 7 VCC 6 OUT 5 REFOUT (REFIN) Thin QFN/μMAX (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 V SENSE , the Kelvin method is recommended. The current into RS+ and RSis 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. SUPPLY VOLTAGE RANGE (V) COMMONMODE RANGE (V) PART REFERENCE 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 ______________________________________________________________________________________ 13 MAX4069–MAX4072 Pin Configurations Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TQFN-EP T833-2 21-0137 8 µMAX U8-1 21-0036 10 µMAX U10-2 21-0061 6, 8, &10L, DFN THIN.EPS MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference 14 ______________________________________________________________________________________ Bidirectional, High-Side, Current-Sense Amplifiers with Reference COMMON DIMENSIONS PACKAGE VARIATIONS SYMBOL MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e A 0.70 0.80 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF E 2.90 3.10 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF A1 0.00 0.05 T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF L 0.20 0.40 T1033-2 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF k 0.25 MIN. T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF A2 0.20 REF. T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF ______________________________________________________________________________________ 15 MAX4069–MAX4072 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 8LUMAXD.EPS MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference α α 16 ______________________________________________________________________________________ Bidirectional, High-Side, Current-Sense Amplifiers with Reference 10LUMAX.EPS α α ______________________________________________________________________________________ 17 MAX4069–MAX4072 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense Amplifiers with Reference Revision History REVISION NUMBER REVISION DATE 3 11/08 DESCRIPTION Added information for RG1 and RG2 PAGES CHANGED 10 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 18 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.