19-1548; Rev 0; 10/99 Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output High-side current monitoring is especially useful in battery-powered systems since it does not interfere with the ground path of the battery charger. The input common-mode range of 0 to +28V is independent of the supply voltage and ensures that the current-sense feedback remains viable even when connected to a 2cell battery pack in deep discharge. The user can set the full-scale current reading by choosing the device (T, F, or H) with the desired voltage gain and selecting the appropriate external sense resistor. This capability offers a high level of integration and flexibility, resulting in a simple and compact current-sense solution. For higher bandwidth applications, refer to the MAX4173T/F/H data sheet. Applications Power-Management Systems Features ♦ Low-Cost, Compact Current-Sense Solution ♦ 30µA Supply Current ♦ +2.7V to +28V Operating Supply ♦ 0.18% Full-Scale Accuracy ♦ Low 1.5Ω Output Impedance ♦ Three Gain Versions Available +20V/V (MAX4372T) +50V/V (MAX4372F) +100V/V (MAX4372H) ♦ Wide 0 to +28V Common-Mode Range, Independent of Supply Voltage ♦ Available in Space-Saving SOT23-5 Package Ordering Information PART TEMP. RANGE PIN-PACKAGE TOP MARK MAX4372TEUK-T -40°C to +85°C 5 SOT23-5 ADIU MAX4372TESA -40°C to +85°C 8 SO MAX4372FEUK-T -40°C to +85°C 5 SOT23-5 MAX4372FESA -40°C to +85°C 8 SO — ADIV — MAX4372HEUK-T -40°C to +85°C 5 SOT23-5 ADIW MAX4372HESA -40°C to +85°C 8 SO — Note: Gain values are as follows: +20V/V for the T version, +50V/V for the F version, and +100V/V for the H version. General-System/Board-Level Current Monitoring Notebook Computers Portable/Battery-Powered Systems Smart-Battery Packs/Chargers Cell Phones Typical Operating Circuit Precision-Current Sources Pin Configurations ILOAD TOP VIEW GND OUT VCC 1 2 5 RS- VCC 1 N.C. 2 MAX4372T/F/H 4 RS+ 8 RS+ 7 N.C. 3 6 RS- OUT 4 5 N.C. GND 3 GND MAX4372T/F/H MAX4372T/F/H A/D CONVERTER VCC +2.7V TO +28V 0.1µF SOT23-5 SO RS- RSENSE OUT VCC VSENSE LOAD/ BATTERY RS+ VIN 0 TO 28V ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX4372T/F/H General Description The MAX4372 low-cost, precision, high-side currentsense amplifier is available in a tiny, space-saving SOT23-5 package. Offered in three gain versions (T = +20V/V, F = +50V/V, and H = +100V/V), this device operates from a single +2.7V to +28V supply and consumes only 30µA. It features a voltage output that eliminates the need for gain-setting resistors and is ideal for today’s notebook computers, cell phones, and other systems where battery/DC current monitoring is critical. MAX4372T/F/H Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output ABSOLUTE MAXIMUM RATINGS VCC, RS+, RS- to GND ...........................................-0.3V to +30V OUT to GND ...........................................................-0.3V to +15V Differential Input Voltage (VRS+ - VRS-) ..............................±0.3V Current into Any Pin..........................................................±10mA Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C).............571mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec). ............................+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+ = 0 to +28V, VCC = +2.7V to +28V, VSENSE = 0, RLOAD = 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Operating Voltage Range (Note 2) SYMBOL CONDITIONS MIN TYP MAX UNITS VCC 2.7 28 V Common-Mode Input Range (Note 3) VCMR 0 28 V Common-Mode Rejection CMR Supply Current Leakage Current ICC IRS+, IRSIRS+ Input Bias Current IRSFull-Scale Sense Voltage (Note 4) VSENSE Full-Scale Accuracy (Note 5) VRS+ > 2V 85 VRS+ > 2V, VSENSE = 5mV 30 60 µA 0.05 1.2 µA VCC = 0 VRS+ > 2V 0 1 VRS+ ≤ 2V -25 2 VRS+ > 2V 0 2 VRS+ ≤ 2V -50 150 Gain = +100V/V 100 ±0.18 VSENSE = 100mV, VCC = 12V, VRS+ = 12V (Note 6) 2 mV ±3 % ±6 VSENSE = 100mV, VCC = 28V, VRS+ = 28V (Note 6) ±0.15 ±7 VSENSE = 100mV, VCC = 12V, VRS+ = 0.1V (Note 6) ±1 ±28 VSENSE = 6.25mV, VCC = 12V, VRS+ = 12V (Note 7) ±0.15 % OUT Low Voltage OUT High Voltage µA 2 Gain = +20V/V or +50V/V VSENSE = 100mV, VCC = 12V, VRS+ = 12V, TA = +25°C (Note 6) Total OUT Voltage Error (Note 5) dB VCC = 2.7V VCC - VOH IOUT = 10µA 2.6 IOUT = 100µA 9 65 0.1 0.25 VCC = 2.7V, IOUT = -500µA _______________________________________________________________________________________ mV V Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output (VRS+ = 0 to +28V, VCC = +2.7V to +28V, VSENSE = 0, RLOAD = 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER -3dB Bandwidth SYMBOL BW CONDITIONS VRS+ = 12V, VCC = 12V, CLOAD = 10pF MIN 275 VSENSE = 100mV, gain = +50V/V 200 VSENSE = 100mV, gain = +100V/V 110 VSENSE = 6.25mV 50 MAX4372T Gain TYP VSENSE = 100mV, gain = +20V/V UNITS kHz 20 MAX4372F 50 MAX4372H 100 Gain Accuracy VSENSE = 20mV to 100mV TA = +25°C VSENSE = 6.25mV to 100mV 20 OUT Settling Time to 1% of Final Value Gain = +20V/V, VCC = 12V, VRS+ = 12V, CLOAD = 10pF VSENSE = 100mV to 6.25mV 20 Capacitive Load Stability MAX ±0.25 TA = -40°C to +85°C V/V ±2.5 ±5.5 % µs No sustained oscillations OUT Output Resistance ROUT VSENSE = 100mV Power-Supply Rejection PSR VOUT = 2V, VRS+ > 2V 75 1000 pF 1.5 Ω 85 dB Power-Up Time to 1% of Final Value VCC = 12V, VRS+ = 12V, VSENSE = 100mV, CLOAD = 10pF 0.5 ms Saturation Recovery Time (Note 8) VCC = 12V, VRS+ = 12V, CLOAD = 10pF 0.1 ms Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design. Note 2: Guaranteed by PSR test. Note 3: Guaranteed by OUT Voltage Error test. Note 4: Output voltage is internally clamped not to exceed 12V. Note 5: Total OUT voltage error is the sum of gain and offset voltage errors. Note 6: Measured at IOUT = -500µA (RLOAD = 4kΩ for gain = +20V/V, RLOAD = 10kΩ for gain = +50V/V, RLOAD = 20kΩ for gain = +100V/V). Note 7: +6.25mV = 1/16 of +100mV full-scale voltage (C/16). Note 8: The device will not reverse phase when overdriven. _______________________________________________________________________________________ 3 MAX4372T/F/H ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = +12V, VRS+ = 12V, VSENSE = 100mV, TA = +25°C, unless otherwise noted.) AV = +100V/V AV = +50V/V 30.0 35 AV = +20V/V 27.5 20 15 8 12 16 20 24 -40 28.0 -15 10 35 60 85 VSENSE = 5mV 0 4 8 12 16 20 24 TOTAL OUTPUT ERROR vs. VSENSE POWER-SUPPLY REJECTION vs. FREQUENCY 1.0 -0.6 -45 -50 -55 AV = +100V/V 0.5 AV = +50V/V PSR (dB) OUTPUT ERROR (%) G = +50V/V G = +20V/V -40 28 MAX4372T toc06 1.5 -0.8 AV = +20V/V 0 -60 -65 -70 -75 -80 -0.5 -1.0 -85 15 20 25 30 -90 0 50 1.4 0.8 G = +50V/V G = +100V/V 0.4 G = +20V/V 10 15 20 300 100 1k -0.2 25 COMMON-MODE VOLTAGE (V) 30 AV = +100V/V -0.4 100k TOTAL OUTPUT ERROR vs. TEMPERATURE AV = +50V/V -0.3 10k FREQUENCY (Hz) AV = +20V/V -0.1 GAIN ACCURACY (%) 1.0 5 250 GAIN ACCURACY vs. TEMPERATURE 1.2 0 200 0 MAX4372T toc07 1.6 0.2 150 VSENSE (mV) TOTAL OUTPUT ERROR vs. COMMON-MODE VOLTAGE 0.6 100 -0.5 -0.6 -0.7 1.0 0.8 0.6 0.4 AV = +50V/V 0.2 0 -0.2 -0.4 -0.8 -0.6 -0.9 -0.8 -1.0 MAX4372T toc09 10 TOTAL OUTPUT ERROR (%) 5 MAX4372T toc08 0 -1.0 SUPPLY VOLTAGE (V) 4 AV = +20V/V 29.0 TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE -0.4 0 AV = +50V/V 29.5 COMMON-MODE VOLTAGE (V) -0.2 -1.2 30.0 TEMPERATURE (°C) 0.4 0 0 28 30.5 SUPPLY VOLTAGE (V) G = +100V/V 0.2 VSENSE = 5mV MAX4372T toc05 4 MAX4372 toc04 0 31.0 28.5 5 0.6 OUTPUT ERROR (%) 25 10 VSENSE = 5mV 25.0 30 AV = +100V/V 31.5 SUPPLY CURRENT (µA) 32.5 32.0 MAX4372T toc02 MAX4372 toc01 40 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 35.0 SUPPLY CURRENT vs. COMMON-MODE VOLTAGE SUPPLY CURRENT vs. TEMPERATURE MAX4372 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE OUTPUT ERROR (%) MAX4372T/F/H Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output AV = +100V/V AV = +20V/V -1.0 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output MAX4372T SMALL-SIGNAL TRANSIENT RESPONSE MAX4372F SMALL-SIGNAL TRANSIENT RESPONSE MAX4372H SMALL-SIGNAL TRANSIENT RESPONSE MAX4372T toc10 MAX4372T toc11 MAX4372T toc12 30mV 30mV VSENSE 30mV VSENSE VSENSE 10mV 10mV 600mV VOUT 10mV 1.5V VOUT 3V VOUT 200mV 1V 0.5V 20µs/div 20µs/div 20µs/div MAX4372F LARGE-SIGNAL TRANSIENT RESPONSE MAX4372T LARGE-SIGNAL TRANSIENT RESPONSE MAX4372T toc14 MAX4372T toc13 150mV VSENSE 150mV VSENSE 50mV 50mV 3V 7.5V VOUT VOUT 2.5V 1V 20µs/div 20µs/div MAX4372H LARGE-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL GAIN vs. FREQUENCY MAX4372T toc15 MAX4372T toc16 3 2 1 100mV VSENSE G = +50V/V 0 10V GAIN (dB) 0 G = +20V/V -1 -2 -3 G = +100V/V -4 VOUT -5 -6 0 -7 -8 20µs/div 1k 10k 100k 1M FREQUENCY (Hz) _______________________________________________________________________________________ 5 MAX4372T/F/H Typical Operating Characteristics (continued) (VCC = +12V, VRS+ = 12V, VSENSE = 100mV, TA = +25°C, unless otherwise noted.) MAX4372T/F/H Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output Pin Description PIN NAME FUNCTION SOT23-5 1 SO 3 GND Ground 2 4 OUT Output Voltage. VOUT is proportional to the magnitude of VSENSE (VRS+ - VRS-). 3 1 VCC Supply Voltage 4 8 RS+ Power Connection to the External Sense Resistor 5 6 RS- Load-Side Connection to the External Sense Resistor — 2, 5, 7 N.C. No Connection. Not internally connected. _______________Detailed Description The MAX4372 high-side current-sense amplifier features a 0 to +28V input common-mode range that is independent of supply voltage. This feature allows the monitoring of current flow out of a battery in deep discharge, and also enables high-side current sensing at voltages far in excess of the supply voltage (VCC). Current flows through the sense resistor, generating a sense voltage (Figure 1). Since A1’s inverting input is high impedance, the voltage on the negative terminal equals VIN - VSENSE. A1 forces its positive terminal to match its negative terminal; therefore, the voltage across RG1 (VIN - V1-) equals VSENSE. This creates a current to flow through RG1 equal to VSENSE / RG1. The transistor and current mirror amplify the current by a factor of β. This makes the current flowing out of the current mirror equal to: IM = β VSENSE / RG1 A2’s positive terminal presents high impedance, so this current flows through RGD, with the following result: V2+ = RGD β · VSENSE / RG1 R1 and R2 set the closed-loop gain for A2, which amplifies V2+, yielding: VOUT = RGD · β · VSENSE / RG1 (1 + R2 / R1) The gain of the device equals: VOUT = RGD · β (1 + R2 / R1) / RG1 VSENSE __________Applications Information Recommended Component Values The MAX4372 operates over a wide variety of current ranges with different sense resistors. Table 1 lists common resistor values for typical operation of the MAX4372. 6 VIN 0 TO +28V RG1 +2.7V TO +28V RS+ V1+ VCC A1 RSENSE VSENSE RSV1CURRENT MIRROR RGD IM TO LOAD MAX4372T/F/H OUT ILOAD RG2 V2+ A2 V2- R2 R1 GND Figure 1. Functional Diagram Choosing RSENSE Given the gain and maximum load current, select RSENSE such that VCC - VOUT does not exceed +0.25V and VOUT does not exceed +10V. To measure lower currents more accurately, use a high value for RSENSE. A higher value develops a higher sense voltage, which overcomes offset voltage errors of the internal current amplifier. In applications monitoring very high current, ensure RSENSE is able to dissipate its own I2R losses. If the resistor’s rated 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. _______________________________________________________________________________________ Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output FULL-SCALE LOAD CURRENT, ILOAD (A) CURRENT-SENSE RESISTOR, RSENSE (mΩ) 0.1 1000 1 100 5 20 10 10 Using a PC Board Trace as RSENSE If the cost of RSENSE is an issue and accuracy is not critical, use the alternative solution shown in Figure 2. This solution uses copper PC board traces to create a sense resistor. The resistivity of a 0.1-inch-wide trace of 2-ounce copper is about 30mΩ/ft. The resistance temperature coefficient of copper is fairly high (approximately 0.4%/°C), so systems that experience a wide temperature variance must compensate for this effect. In addition, self-heating will introduce a nonlinearity error. Do not exceed the maximum power dissipation of the copper trace. For example, the MAX4372T (with a maximum load current of 10A and an RSENSE of 5mΩ) creates a full-scale VSENSE of 50mV that yields a maximum VOUT of 1V. RSENSE, in this case, requires about 2 inches of 0.1inch-wide copper trace. GAIN (V/V) FULL-SCALE OUTPUT VOLTAGE (FULL-SCALE VSENSE = 100mV), VOUT (V) 20 2.0 50 5.0 100 10.0 20 2.0 50 5.0 100 10.0 20 2.0 50 5.0 100 10.0 20 2.0 50 5.0 100 10.0 INPUT 0.3in COPPER MAX4372T/F/H Table 1. Recommended Component Values LOAD/BATTERY RSENSE 0.1in COPPER 0.3in COPPER VSENSE RS+ VCC +2.7V TO +28V MAX4372T/F/H RS- OUT GND Chip Information TRANSISTOR COUNT: 225 Figure 2. Connections Showing Use of PC Board _______________________________________________________________________________________ 7 Low-Cost, SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output SOT5L.EPS MAX4372T/F/H Package Information 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.