Low-Cost, UCSP/SOT23, Micropower, High-Side Current-Sense Amplifier with Voltage Output

Transcription

1 ; Rev 3; 12/5 Low-Cost, UCSP/SOT23, Micropower, High-Side General Description The MAX4372 low-cost, precision, high-side currentsense amplifier is available in a tiny, space-saving SOT23-5-pin package. Offered in three gain versions (T = 2V/V, F = 5V/V, and H = 1V/V), this device operates from a single 2.7V to 28V supply and consumes only 3µA. 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. 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 to 28V is independent of the supply voltage and ensures that the current-sense feedback remains viable even when connected to a 2-cell 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 General-System/Board-Level Current Monitoring Notebook Computers Portable/Battery-Powered Systems Smart-Battery Packs/Chargers Cell Phones Precision-Current Sources TOP VIEW SOT23-5 RS+ Pin Configurations A B TOP VIEW (BUMPS ON BOTTOM) RS+ UCSP Pin Configurations continued at end of datasheet. Features Low-Cost, Compact Current-Sense Solution 3µA Supply Current 2.7V to 28V Operating Supply.18% Full-Scale Accuracy.3mV Input Offset Voltage Low 1.5Ω Output Impedance Three Gain Versions Available 2V/V (MAX4372T) 5V/V (MAX4372F) 1V/V (MAX4372H) Wide to 28V Common-Mode Range, Independent of Supply Voltage Available in a Space-Saving 5-Pin SOT23 Package and 3 x 2 UCSP (1mm x 1.5mm) Package PART MAX4372TEUK-T MAX4372TESA Ordering Information TEMP RANGE PIN-PACKAGE -4 C to +85 C -4 C to +85 C 5 SOT SO TOP MARK ADIU MAX4372TEBT-T -4 C to +85 C 3 x 2 UCSP ACX Note: Gain values are as follows: 2V/V for the T version, 5V/V for the F version, and 1V/V for the H version. Ordering Information continued at end of datasheet. A/D CONVERTER +2.7V TO +28V.1µF Typical Operating Circuit 1 5 RS- RS- RS- RS+ R SENSE V IN TO 28V I LOAD LOAD/ BATTERY UCSP is a trademark of Maxim Integrated Products, Inc. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATINGS, RS+, RS- to...-.3v to +3V to...-.3v to +15V Differential Input Voltage (V RS+ - V RS- )...±.3V Current into Any Pin...±1mA Continuous Power Dissipation (T A = +7 C) 5-Pin SOT23 (derate 7.1mW/ C above +7 C)...571mW 8-Pin SO (derate 5.88mW/ C above +7 C)...471mW 3 x 2 UCSP (derate 3.4mW/ C above +7 C) mW 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 Operating Temperature Range...-4 C to +85 C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s) C Bump Temperature (soldering) Infrared (15s)...+2 C Vapor Phase (2s) C (V RS+ = to 28V, = 2.7V to 28V, =, R LOAD = 1MΩ, T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Operating Voltage Range (Note 2) V Common-Mode Input Range (Note 3) Common-Mode Rejection Supply Current Leakage Current Input Bias Current Full-Scale Sense Voltage (Note 4) Input Offset Voltage (Note 5) Full-Scale Accuracy (Note 5) V CMR 28 CMR I CC V RS+ > 2V V RS+ > 2V, = 5mV I RS+, I RS- = I RS+ V RS+ > 2V 1 V RS+ 2V I RS- V RS+ > 2V 2 V RS+ 2V -5 2 Gain = 2V/V or 5V/V 15 Gain = 1V/V 1 T A = +25 C MAX4372_ESA.3 ±.8 = V RS+ = 12V MAX4372_EUK, _EBT.3 ±1.3 V OS T A = T MIN to T MAX MAX4372_ESA ±1.1 = V RS+ = 12V MAX4372_EUK, _EBT ±1.9 = 1mV, = 12V, V RS+ = 12V, T A = +25 C (Note 7) ±.18 ±3 V db µa µa µa mv mv % = 1mV, = 12V, V RS+ = 12V (Note 7) ±6 Total Voltage Error (Note 6) = 1mV, = 28V, V RS+ = 28V (Note 7) = 1mV, = 12V, V RS+ =.1V (Note 7) ±.15 ±7 ±1 ±28 % = 6.25mV, = 12V, V RS+ = 12V (Note 8) ±.15 Low Voltage High Voltage - V OH I = 1µA = 2.7V I = 1µA = 2.7V, I = -5µA mv V 2

3 ELECTRICAL CHARACTERISTICS (continued) (V RS+ = to 28V, = 2.7V to 28V, =, R LOAD = 1MΩ, T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +25 C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS -3dB Bandwidth BW V RS+ = 12V, = 12V, C LOAD = 1pF = 2mV, gain = 2V/V = 2mV, gain = 5V/V = 2mV, gain = 1V/V = 6.25mV 5 MAX4372T 2 Gain MAX4372F 5 MAX4372H 1 Gain Accuracy = 2mV T A = +25 C ±.25 ±2.5 to 1mV T A = -4 C to +85 C ±5.5 Settling Time to 1% of Final Value Capacitive-Load Stability Output Resistance Power-Supply Rejection Power-Up Time to 1% of Final Value R PSR Gain = 2V/V, = 12V, V RS+ = 12V, C LOAD = 1pF No sustained oscillations = 1mV V = 2V, V RS+ > 2V = 6.25mV to 1mV = 1mV to 6.25mV = 12V, V RS+ = 12V, = 1mV, C LOAD = 1pF khz V/V % µs pf Ω db ms Saturation Recovery Time (Note 9) = 12V, V RS+ = 12V, C LOAD = 1pF.1 ms Note 1: All devices are 1% production tested at T A = +25 C. All temperature limits are guaranteed by design. Note 2: Guaranteed by PSR test. Note 3: Guaranteed by Voltage Error test. Note 4: Output voltage is internally clamped not to exceed 12V. Note 5: V OS is extrapolated from the gain accuracy tests. Note 6: Total voltage error is the sum of gain and offset voltage errors. Note 7: Measured at I = -5µA (R LOAD = 4kΩ for gain = 2V/V, R LOAD = 1kΩ for gain = 5V/V, R LOAD = 2kΩ for gain = 1V/V). Note 8: 6.25mV = 1/16 of 1mV full-scale voltage (C/16). Note 9: The device will not reverse phase when overdriven. 3

4 Typical Operating Characteristics ( = 12V, V RS+ = 12V, = 1mV, T A = +25 C, unless otherwise noted.) SUPPLY CURRENT (µa) SUPPLY CURRENT vs. SUPPLY VOLTAGE A V = +1V/V A V = +5V/V A V = +2V/V MAX4372 toc1 SUPPLY CURRENT (µa) SUPPLY CURRENT vs. TEMPERATURE MAX4372T toc2 SUPPLY CURRENT (µa) SUPPLY CURRENT vs. COMMON-MODE VOLTAGE A V = +1V/V A V = +5V/V A V = +2V/V MAX4372 toc3 25. = 5mV SUPPLY VOLTAGE (V) 5 = 5mV TEMPERATURE ( C) 28.5 = 5mV COMMON-MODE VOLTAGE (V) PUT ERROR (%) G = +5V/V G = +2V/V TOTAL PUT ERROR vs. SUPPLY VOLTAGE G = +1V/V MAX4372 toc4 PUT ERROR (%) TOTAL PUT ERROR vs. A V = +1V/V A V = +2V/V A V = +5V/V MAX4372T toc5 PSR (db) POWER-SUPPLY REJECTION vs. FREQUENCY MAX4372T toc SUPPLY VOLTAGE (V) (mv) k 1k 1k FREQUENCY (Hz) PUT ERROR (%) TOTAL PUT ERROR vs. COMMON-MODE VOLTAGE G = +5V/V G = +1V/V G = +2V/V COMMON-MODE VOLTAGE (V) MAX4372T toc7 GAIN ACCURACY (%) GAIN ACCURACY vs. TEMPERATURE A V = +2V/V TEMPERATURE ( C) A V = +5V/V A V = +1V/V MAX4372T toc8 TOTAL PUT ERROR (%) TOTAL PUT ERROR vs. TEMPERATURE A V = +5V/V A V = +2V/V A V = +1V/V TEMPERATURE ( C) MAX4372T toc9 4

5 Typical Operating Characteristics (continued) ( = 12V, V RS+ = 12V, = 1mV, T A = +25 C, unless otherwise noted.) V MAX4372T SMALL-SIGNAL TRANSIENT RESPONSE MAX4372T toc1 3mV 1mV 6mV 2mV V MAX4372F SMALL-SIGNAL TRANSIENT RESPONSE MAX4372T toc11 3mV 1mV 1.5V.5V V MAX4372H SMALL-SIGNAL TRANSIENT RESPONSE MAX4372T toc12 3mV 1mV 3V 1V 2µs/div 2µs/div 2µs/div MAX4372T LARGE-SIGNAL TRANSIENT RESPONSE MAX4372T toc13 MAX4372F LARGE-SIGNAL TRANSIENT RESPONSE MAX4372T toc14 15mV 15mV 5mV 5mV 3V 7.5V V V 1V 2.5V 2µs/div 2µs/div MAX4372H LARGE-SIGNAL TRANSIENT RESPONSE MAX4372T toc15 V 1mV 1V GAIN (db) SMALL-SIGNAL GAIN vs. FREQUENCY G = 5V/V G = 2V/V G = 1V/V = 2mV MAX4372T toc16 2µs/div -8 1k 1k 1k FREQUENCY (Hz) 1M 5

6 SOT23 PIN SO 1 3 A2 Ground 2 4 UCSP A3 NAME FUNCTION Pin Description Output Voltage. V is proportional to the magnitude of (V RS+ - V RS- ). V2-3 1 A1 Supply Voltage. Use at least a.1µf capacitor to decouple from fast transients. 4 8 B1 RS+ Power Connection to the External Sense Resistor 5 6 B3 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 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: V = RGD β VSENSE / RG1 (1 + R2 / R1) The gain of the device equals: V = R GD 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 MAX V TO 28V CURRENT MIRROR I M R2 A1 A2 Figure 1. Functional Diagram RG1 1kΩ R G2 1kΩ Choosing R SENSE Given the gain and maximum load current, select RSENSE such that V does not exceed VCC -.25V or 1V. 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 I 2 R 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. V1+ V2+ RS- V1- RGD R1 RS+ R SENSE V IN TO 28V I LOAD TO LOAD 6

7 Table 1. Recommended Component Values FULL-SCALE LOAD CURRENT, I LOAD (A) CURRENT-SENSE RESISTOR, R SENSE (mω) GAIN (V/V) FULL-SCALE PUT VOLTAGE (FULL-SCALE = 1mV), V (V) 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.1-inch-wide trace of 2-ounce copper is about 3mΩ/ft. The resistance temperature coefficient of copper is fairly high (approximately.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 1A and an RSENSE of 5mΩ) creates a full-scale VSENSE of 5mV that yields a maximum V of 1V. RSENSE, in this case, requires about 2 inches of.1- inch-wide copper trace. UCSP Applications Information For the latest application details on UCSP construction, dimensions, tape carrier information, printed circuit board techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, go to the Maxim's website at to find the Application Note: UCSP A Wafer-Level Chip-Scale Package. INPUT R SENSE LOAD/BATTERY.3in COPPER.1in COPPER.3in COPPER RS+ 2.7V TO 28V RS- Figure 2. Connections Showing Use of PC Board 7

8 Ordering Information (continued) PART TRANSISTOR COUNT: 225 PROCESS: BiCMOS TEMP RANGE PIN-PACKAGE MAX4372FEUK-T -4 C to +85 C 5 SOT23-5 MAX4372FESA -4 C to +85 C 8 SO MAX4372FEBT-T -4 C to +85 C 3 x 2 UCSP MAX4372HEUK-T -4 C to +85 C 5 SOT23-5 MAX4372HESA -4 C to +85 C 8 SO TOP MARK ADIV ACY ADIW MAX4372HEBT-T -4 C to +85 C 3 x 2 UCSP ACZ Chip Information Pin Configurations (continued) 1 8 RS+ N.C. 2 7 N.C RS- N.C. SO Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to 6L, UCSP.EPS PACKAGE LINE, 3x2 UCSP G 1 1 Note: MAX4372_EBT uses package code B6-2. 8

9 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to N E H INCHES MILLIMETERS DIM MIN MAX MIN MAX A A B C e.5 BSC 1.27 BSC E H L SOICN.EPS 1 TOP VIEW VARIATIONS: DIM D D D INCHES MILLIMETERS MIN MAX MIN MAX N MS AA AB AC D A C e B A1 FRONT VIEW L SIDE VIEW -8 PROPRIETARY INFORMATION TITLE: PACKAGE LINE,.15" SOIC APPROVAL DOCUMENT CONTROL NO. REV B 1 1 9

10 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to SOT-23 5L.EPS PACKAGE LINE, SOT-23, 5L E 1 1 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. 1 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.