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19-1781; Rev 3; 5/04
Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain
General Description
The MAX4376/MAX4377/MAX4378 single, dual, and quad precision high-side current-sense amplifiers are available in space-saving packages. They feature buffered voltage outputs that eliminate the need for gain-setting resistors and are ideal for today's notebook computers, cell phones, and other systems where current monitoring is critical. These precision devices are offered in three fixed-gain versions of 20, 50, and 100: GAIN SUFFIX 20 T 50 F 100 H For example, MAX4376TAUK is a single high-side amplifier with a gain of 20. 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 battery pack in deep discharge. The full-scale current reading can be set by choosing the appropriate voltage gain and external-sense resistor. This capability offers a high level of integration and flexibility, resulting in a simple and compact currentsense solution. The MAX4376/MAX4377/MAX4378 operate over a supply voltage range of +3V to +28V, draw 1mA of supply current per amplifier, and operate over the full automotive temperature range of -40C to +125C. These devices have a wide bandwidth of 2MHz, making them suitable for use inside battery-charger control loops. The buffered outputs drive up to 2mA of output current into a ground-referenced load. The MAX4376 is available in a tiny 5-pin SOT23 package. The MAX4377/MAX4378 are available in spacesaving 8-pin MAX and 14-pin TSSOP packages, respectively.
Features
o Low-Cost, Single/Dual/Quad, High-Side CurrentSense Amplifiers o 0.5% Typical Full-Scale Accuracy o +3V to +28V Supply Operation o Adjustable Current-Sense Capability with External Sense Resistor o Buffered Output Voltage with 2mA Drive o 1mA (typ) Supply Current o 2.0MHz Bandwidth (Gain = +20V/V) o Automotive Temperature Range (-40C to +125C) o Full 0 to 28V Common-Mode Range, Independent of Supply Voltage o Three Gain Versions Available +20V/V (MAX437_T) +50V/V (MAX437_F) +100V/V (MAX437_H) o Available in Space-Saving 5-Pin SOT23 (Single), 8-Pin MAX (Dual), and 14-Pin TSSOP (Quad)
MAX4376/MAX4377/MAX4378
Ordering Information
PART MAX4376 T AUK-T MAX4376FAUK-T MAX4376HAUK-T MAX4376TASA MAX4376FASA MAX4376HASA GAIN (+V/V) 20 50 100 20 50 100 TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C PINPACKAGE 5 SOT23-5 5 SOT23-5 5 SOT23-5 8 SO 8 SO 8 SO TOP MARK ADOG ADOH ADOI -- -- --
Ordering Information continued at end of data sheet.
Pin Configurations
TOP VIEW
OUT 1
Applications
5 RS-
Notebook Computers Current-Limited Power Supplies Fuel Gauges in PC General-System/BoardLevel Current Monitoring Battery Chargers
Portable/Battery-Powered Systems Cell Phones Smart Battery Packages Automotive Current Detect Power Management Systems PA Bias Control
GND 2
MAX4376
VCC 3
4
RS+
SOT23 Pin Configurations continued at end of data sheet. 1
________________________________________________________________ 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.
Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain MAX4376/MAX4377/MAX4378
ABSOLUTE MAXIMUM RATINGS
VCC, RS+, RS- to GND ...........................................-0.3V to +30V OUT to GND ...............................................-0.3V to (VCC + 0.3V) Differential Input Voltage (VRS+ - VRS- ).................................8V Output Short Circuit to VCC ........................................Continuous Output Short Circuit to GND .....................................................1s Current into Any Pin..........................................................20mA Continuous Power Dissipation (TA = +70C) 5-Pin SOT23 (derate 7.1mW/C above +70C)............571mW 8-Pin MAX (derate 4.5mW/C above +70C) .............362mW 8-Pin SO (derate 5.88mW/C above +70C)................471mW 14-Pin SO (derate 8.33mW/C above +70C)..............667mW 14-Pin TSSOP (derate 9.1mW/C above +70C) .........727mW 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+ = 0 to 28V, VSENSE = (VRS+ - VRS- ) = 0V, VCC = +3.0V to +28V, RL = , TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = 25C.) (Note 1)
PARAMETER Operating Voltage Range Common-Mode Input Range Common-Mode Rejection Supply Current per Amplifier Leakage Current SYMBOL VCC VCM CMR ICC IRS+, IRSIRS+ Input Bias Current IRSFull-Scale Sense Voltage VSENSE VSENSE = 100mV, VCC = 12V, VRS+ = 12V VSENSE = 100mV, VCC = 12V, TA = +25C VSENSE = 100mV, VCC = 28V, VRS+ = 28V Total OUT Voltage Error (Note 2) IOUT 2mA VSENSE = 100mV, VCC = 28V, VRS+ = 28V, TA = +25C VSENSE = 100mV, VCC = 12V, VRS+ = 0.1V VSENSE = 6.25mV, VCC = 12V, VRS+ = 12V (Note 3) OUT High Voltage (Note 4) OUT Low Voltage (VCC - VOUT) VCC = 3V, IOUT = 2mA VOL IOUT = 200A, VCC = VRS+ = 12V, VSENSE = 0V, TA = +25C 0.5 0.5 CONDITIONS Guaranteed by PSR test Guaranteed by total OUT voltage error test 2V VRS+ 28V, VSENSE = 100mV VSENSE = 5mV, VRS+ > 2.0V, VCC = 12V VCC = 0V, VRS+ = 28V VRS+ > 2.0V VRS+ 2.0V VRS+ > 2.0V VRS+ 2.0V 0 -400 0 -800 150 6.75 3.25 11 % MIN 3 0 90 1 2.2 8 60 60 120 120 mV A TYP MAX 28 28 UNITS V V dB mA A
5
9
32
7 0.9 25 1.2 40 V mV
2
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Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain
ELECTRICAL CHARACTERISTICS (continued)
(VRS+ = 0 to 28V, VSENSE = (VRS+ - VRS- ) = 0V, VCC = +3.0V to +28V, RL = , TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = 25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS VSENSE = 100mV (gain = +20V/V) Bandwidth BW VCC = 12V VRS+ = 12V CLOAD = 15pF VSENSE = 100mV (gain = +50V/V) VSENSE = 100mV (gain = +100V/V) VSENSE = 6.25mV (Note 3) Slew Rate Gain SR AV VSENSE = 20mV to 100mV, CLOAD = 15pF MAX437_T MAX437_F MAX437_H VSENSE = 10mV to 150mV, VCC = 12V, IOUT = 2mA, gain = 20 and 50 VSENSE = 10mV to 150mV, VCC = 20V, IOUT = 2mA, gain = 100 TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C VSENSE = 6.25mV to 100mV VSENSE = 100mV to 6.25mV 0.5 400 ns 800 1000 5 66 90 2 1 1 pF dB s s s 0.5 MIN TYP 2 1.7 1.2 0.5 10 +20 +50 +100 5.5 2.5 % 5.5 2.5 V/V V/s MAX UNITS
MAX4376/MAX4377/MAX4378
MHz
Gain Accuracy
AV
OUT Setting Time to 1% of Final Value Maximum Capacitive Load Output Resistance Power-Supply Rejection Power-Up Time to 1% of Final Value Saturation Recovery Time to 1% of Final Value Reverse Recovery Time to 1% of Final Value CLOAD ROUT PSR
VCC = 12V, VRS+ = 12V, CLOAD = 15pF No sustained oscillation VSENSE = 100mV
VRS+ > 2V, VOUT = 1.6V, VCC = 3V to 28V VSENSE = 100mV, CLOAD = 15pF VCC = 12V, VRS+ = 12V, CLOAD = 15pF, VSENSE = 100mV VCC = 12V, VRS_ = 12V, CLOAD = 15pF, VSENSE = -100mV to +100mV
Note 1: Note 2: Note 3: Note 4:
All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design. Total OUT Voltage Error is the sum of gain and offset errors. 6.25mV = 1/16 of 100mV full-scale sense voltage. VSENSE such that VOUT is in saturation.
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3
Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain MAX4376/MAX4377/MAX4378
Typical Operating Characteristics
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25C.)
SUPPLY CURRENT (PER AMPLIFIER) vs. TEMPERATURE
MAX4376/7/8 toc02 MAX4376/7/8 toc01
SUPPLY CURRENT (PER AMPLIFIER) vs. SUPPLY VOLTAGE
1.00 0.95 0.90 SUPPLY CURRENT (mA) 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 0.2 0 -50 MAX4376T MAX4376H MAX4376F 1.4 1.2 SUPPLY CURRENT (mA)
TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE (VSENSE = 100mV)
1.0 TOTAL OUTPUT ERROR (%) 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 MAX4376H MAX4376T MAX4376F
MAX4376/7/8 toc03
1.2
MAX4376H 1.0 0.8 0.6 0.4 MAX4376F MAX4376T
-25
0
25
50
75
100
125
0
5
10
15
20
25
30
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE (VSENSE = 6.25mV)
MAX4376/7/8 toc04
TOTAL OUTPUT ERROR vs. COMMON-MODE VOLTAGE
0.8 TOTAL OUTPUT ERROR (%) 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 MAX4376F MAX4376T MAX4376H
MAX4376/7/8 toc05
6 5 4 TOTAL OUTPUT ERROR (%) 3 2 1 0 -1 -2 -3 -4 0 5 10 15 20 25 MAX4376T MAX4376F MAX4376H
1.0
30
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
GAIN ACCURACY vs. TEMPERATURE
MAX4376/7/8 toc06
TOTAL OUTPUT ERROR vs. TEMPERATURE
0.8 TOTAL OUTPUT ERROR (%) 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 MAX4376H MAX4376T MAX4376F
MAX4376/7/8 toc07
2.0 1.5 GAIN ACCURACY (%) 1.0 MAX4376H 0.5 0 -0.5 -1.0 -1.5 -2.0 -50 -25 0 25 50 75 100 MAX4376T MAX4376F
1.0
125
-50
-25
0
25
50
75
100 125 150
TEMPERATURE (C)
TEMPERATURE (C)
4
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Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain
Typical Operating Characteristics (continued)
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25C.)
TOTAL OUTPUT ERROR vs. FULL-SCALE SENSE VOLTAGE
MAX4376/7/8 toc08
MAX4376/MAX4377/MAX4378
MAX4376T SMALL-SIGNAL TRANSIENT RESPONSE (VSENSE = 95mV TO 100mV)
CL = 15pF RL =1k IN 5mV/div
MAX4376 toc09
5 4 TOTAL OUTPUT ERROR (%) 3 2 1 0 -1 -2 0 50 100 VSENSE (mV) 150 MAX4376T MAX4376F MAX4376H
100mV 95mV
2.0V OUT 50mV/div 1.9V
200
2s/div
MAX4376F SMALL-SIGNAL TRANSIENT RESPONSE (VSENSE = 95mV TO 100mV)
MAX4376 toc10
MAX4376H SMALL-SIGNAL TRANSIENT RESPONSE (VSENSE = 95mV to 100mV)
CL = 15pF RL = 5k IN 5mV/div
MAX4376 toc11
CL = 15pF RL = 2.5k IN 5mV/div
100mV 95mV
100mV 95mV
5V OUT 100mV/div 4.75V 2s/div 2s/div OUT 200mV/div
10V
9.5V
MAX4376T LARGE-SIGNAL TRANSIENT RESPONSE (VSENSE = 6mV to 100mV)
MAX4376 toc12
MAX4376F LARGE-SIGNAL TRANSIENT RESPONSE (VSENSE = 6mV to 100mV)
CL = 15pF RL = 2.5k 100mV IN 45mV/div
MAX4376 toc13
CL = 15pF RL = 1k IN 45mV/div
100mV
6mV 2V
6mV
5V OUT 500mV/div 0.120V OUT 2V/div 0.3V
2s/div
2s/div
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5
Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain MAX4376/MAX4377/MAX4378
Typical Operating Characteristics (continued)
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25C.)
MAX4376H LARGE-SIGNAL TRANSIENT RESPONSE (VSENSE = 6mV to 100mV)
MAX4376 toc14
SMALL-SIGNAL GAIN vs. FREQUENCY
40 100mV 35 30 GAIN (dB) 6mV 10V 25 20 15 0.6V 10 5 MAX4376T MAX4376F MAX4376H
MAX4376/7/8 toc15
45
CL = 15pF RL = 5k IN 45mV/div
OUT 3V/div
2s/div
0 1.E+04
1.E+05
1.E+06
1.E+07
FREQUENCY (Hz)
OVERDRIVE RESPONSE AV = +20V/V
MAX4376/7/8 toc16
OUTPUT LOW vs. TEMPERATURE
750mV OUTPUT LOW (mV) 350 300 350mV 250 200 150 100 7V 50 0 -50 -25 0 25 50 75 100 125 MAX4376F MAX4376H MAX4376T
MAX4376/7/8 toc17
400
IN 200mV/div
VOH OUT 2V/div
TIME (500ns)
TEMPERATURE (C)
6
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Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain
Pin Description
PIN MAX4376 SOT23-5 MAX4376 SO-8 MAX4377 MAX-8/ SO-8 MAX4378 SO-14/ TSSOP-14 Output Voltage. VOUT_ is proportional to the magnitude of the sense voltage (VRS+ - VRS-). VOUT_ is approximately zero when VRS - > VRS - + (no phase reversal). Ground Supply Voltage Power connection to the external sense resistor Load-side connection to the external sense resistor No Connection. Not internally connected. NAME FUNCTION
MAX4376/MAX4377/MAX4378
1
4
1, 7
1, 7, 8, 14
OUT, OUT_
2 3 4 5 --
3 1 8 6 2, 5, 7
4 8 3, 5 2, 6 --
11 4 3, 5, 10, 12 2, 6, 9, 13 --
GND VCC RS+, RS_+ RS-, RS_N.C.
Detailed Description
The MAX4376/MAX4377/MAX4378 high-side currentsense amplifiers feature a 0 to +28V input common-mode range that is independent of supply voltage. This feature allows the monitoring of current out of a battery in deep discharge and also enables high-side current sensing at voltages greater than the supply voltage (VCC). The MAX4376/MAX4377/MAX4378 operate as follows: current from the source flows through RSENSE to the load (Figure 1). Since the internal sense amplifier's inverting input has high impedance, negligible current flows through RG2 (neglecting the input bias current). Therefore, the sense amplifier's inverting-input voltage equals VSOURCE - (ILOAD)(RSENSE). The amplifier's open-loop gain forces its noninverting input to the same voltage as the inverting input. Therefore, the drop across RG1 equals (I LOAD ) (R SENSE ). Since I RG1 flows through RG1, I RG1 = (ILOAD)(RSENSE)/RG1. The internal current mirror multiplies IRG1 by a current gain factor, , to give IRGD = x I RG1 . Solving I RGD = x (I LOAD )(R SENSE )/RG1. Therefore: VOUT = x (RGD/RG1)(RSENSE x ILOAD) x amp gain where amp gain is 2, 5, or 10. The part's gain equals ( x RGD / RG1) x amp gain. Therefore: VOUT = (GAIN)(RSENSE)(ILOAD) where GAIN = 20 for MAX437_T. GAIN = 50 for MAX437_F. GAIN = 100 for MAX437_H.
Set the full-scale output range by selecting RSENSE and the appropriate gain version of the MAX4376/ MAX4377/MAX4378.
Applications Information
Recommended Component Values
The MAX4376/MAX4377/MAX4378 sense a wide variety of currents with different sense resistor values. Table 1 lists common resistor values for typical operation of the MAX4376/MAX4377/MAX4378.
Choosing RSENSE To measure lower currents more accurately, use a high value for RSENSE. The high value develops a higher sense voltage that reduces offset voltage errors of the internal op amp. In applications monitoring very high currents, RSENSE must be able to dissipate the 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.
If ISENSE has a large high-frequency component, minimize the inductance of RSENSE. Wire-wound resistors have the highest inductance, metal-film resistors are somewhat better, and low-inductance metal-film resistors are best suited for these applications.
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 monitor accurately the battery's current regardless of polarity. Figure 2 shows the MAX4377 used as a bidirectional current
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7
Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain MAX4376/MAX4377/MAX4378
Table 1. Recommended Component Values
FULL-SCALE LOAD CURRENT, ILOAD (A) 0.1 CURRENT-SENSE RESISTOR, RSENSE (m) 1000 GAIN (+V/V) 20 50 100 1 100 20 50 100 5 20 20 50 100 10 10 20 50 100
RSENSE RS+ IRG1 +3V TO +28V VCC RG1 RG2 ILOAD TO LOAD BATTERY
FULL-SCALE OUTPUT VOLTAGE (FULL-SCALE VSENSE = 100mV), VOUT (V) 2.0 5.0 10.0 2.0 5.0 10.0 2.0 5.0 10.0 2.0 5.0 10.0
VSOURCE 0 TO +28V
RSENSE
RS-
BATTERY +3V TO +28V
MAX4376
SYSTEM AND CHARGER
VCC RS1+
A1
RS1-
OUT1
CURRENT MIRROR IRGD RGD GND
OUT
VOUT
MAX4377
AV = 2, 5, OR 10 OUT
RS2OUT2 RS2+
Figure 1. Functional Diagram
monitor. This is useful for implementing either smart battery packs or fuel gauges.
Current Source Circuit
Figure 3 shows a block diagram using the MAX4376 with a switching regulator to make a current source.
Figure 2. Bidirectional Current Monitor
8
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Single/Dual/Quad, High-Side Current-Sense Amplifiers with Internal Gain
Chip Information
VIN MAX1745 LOW-COST SWITCHING REGULATOR 0 TO +18V VSENSE RSENSE +3V TO +28V 0.1F MAX4376 OUT GND LOAD/ BATTERY RS+ VCC RSILOAD
MAX4376/MAX4377/MAX4378
MAX4376_ TRANSISTOR COUNT: 162 MAX4377_ TRANSISTOR COUNT: 324 MAX4378_ TRANSISTOR COUNT: 648 PROCESS: BiCMOS
Figure 3. Current Source
Pin Configurations (continued)
TOP VIEW
VCC 1 N.C. 2 GND 3 8 RS+ N.C. RSN.C. OUT1 1 RS1- 2 RS1+ GND 3 4 8 VCC OUT2 RS2RS2+ OUT1 1 RS1- 2 RS1+ 3 14 OUT4
MAX4376
7 6 5
MAX4377
7 6 5
MAX4378
13 RS412 RS4+ 11 GND 10 RS3+ 9 8 RS3OUT3
OUT 4
VCC 4 RS2+ 5
SO
MAX/SO
RS2- 6 OUT2 7
SO/TSSOP
Ordering Information (continued)
PART MAX4377 T AUA MAX4377FAUA MAX4377HAUA MAX4377TASA MAX4377FASA MAX4377HASA MAX4378 T AUD MAX4378FAUD MAX4378HAUD MAX4378TASD MAX4378FASD MAX4378HASD GAIN (+V/V) 20 50 100 20 50 100 20 50 100 20 50 100 TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C PINPACKAGE 8 MAX 8 MAX 8 MAX 8 SO 8 SO 8 SO 14 TSSOP 14 TSSOP 14 TSSOP 14 SO 14 SO 14 SO TOP MARK -- -- -- -- -- -- -- -- -- -- -- --
Typical Operating Circuit
0 TO +28V VSENSE RSENSE +3V TO +28V 0.1F MAX4376T/F/H A/D CONVERTER OUT GND LOAD/ BATTERY RS+ VCC RSILOAD
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.
9 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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