MAXIM MAX4378TASD

19-1781; Rev 2; 10/00
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
Features
♦ Low-Cost Single/Dual/Quad High-Side CurrentSense Amplifiers
♦ ±0.5% Typical Full-Scale Accuracy
♦ +3V to +28V Supply Operation
♦ Adjustable Current-Sense Capability with External
Sense Resistor
♦ Buffered Output Voltage with 2mA Drive
♦ 1mA (typ) Supply Current
♦ 2.0MHz Bandwidth (Gain = +20V/V)
♦ Automotive Temperature Range (-40°C to +125°C)
♦ Full 0 to 28V Common-Mode Range, Independent
of Supply Voltage
♦ Three Gain Versions Available
+20V/V (MAX437_T)
+50V/V (MAX437_F)
+100V/V (MAX437_H)
♦ Available in Space-Saving 5-pin SOT23 (Single),
8-pin µMAX (Dual), and 14-pin TSSOP (Quad)
Ordering Information
PART
GAIN
(+V/+V)
TEMP.
RANGE
PINPACKAGE
TOP
MARK
MAX4376 T AUK-T
20
-40°C to +125°C
5 SOT23-5
ADOG
MAX4376FAUK-T
50
-40°C to +125°C
5 SOT23-5
ADOH
MAX4376HAUK-T
100
-40°C to +125°C
5 SOT23-5
ADOI
MAX4376TASA
20
-40°C to +125°C
8 SO
—
MAX4376FASA
50
-40°C to +125°C
8 SO
—
MAX4376HASA
100
-40°C to +125°C
8 SO
—
Ordering Information continued at end of data sheet.
Pin Configurations
TOP VIEW
Applications
OUT 1
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
5
RS-
4
RS+
MAX4376
VCC 3
SOT23
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX4376/MAX4377/MAX4378
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 -40°C to +125°C. 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 µMAX and 14-pin TSSOP packages,
respectively.
MAX4376/MAX4377/MAX4378
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
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 = +70°C)
5-pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
8-pin µMAX (derate 4.5mW/°C above +70°C) .............362mW
8-pin SO (derate 5.88mW/°C above +70°C)................471mW
14-pin SO (derate 8.33mW/°C above +70°C)..............667mW
14-pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW
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+ = 0 to 28V, VSENSE = (VRS+ - VRS- ) = 0, VCC = +3.0V to +28V, RL = ∞, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = 25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
UNITS
VCC
Guaranteed by PSR test
3
28
V
Common-Mode Input Range
VCM
Guaranteed by total OUT voltage error test
0
28
V
Common-Mode Rejection
CMR
2.2
mA
8
µA
Supply Current per Amplifier
Leakage Current
ICC
IRS+, IRSIRS+
Input Bias Current
IRSFull-Scale Sense Voltage
2V ≤ VRS+ ≤ 28V, VSENSE = 100mV
90
VSENSE = 5mV, VRS+ > 2.0V, VCC = 12V
1
VCC = 0, VRS+ = 28V
0
VRS+ ≤ 2.0V
-400
60
VRS+ > 2.0V
0
120
VRS+ ≤ 2.0V
-800
VSENSE
60
OUT High Voltage (Note 4)
OUT Low Voltage
±0.5
±3.25
±11
VSENSE = 100mV,
VCC = 28V, VRS+ = 28V,
TA = +25°C
±0.5
±5
VSENSE = 100mV,
VCC = 12V, VRS+ = 0.1V
±9
±32
VSENSE = 6.25mV,
VCC = 12V, VRS+ = 12V
(Note 3)
±7
(VCC - VOUT) VCC = 3V, IOUT = 2mA
VOL
mV
±6.75
VSENSE = 100mV,
VCC = 28V, VRS+ = 28V
IOUT ≤2mA
IOUT = 200µA, VCC = 3V, VSENSE = 0
µA
120
150
VSENSE = 100mV,
VCC = 12V, TA = +25°C
Total OUT Voltage Error (Note 2)
dB
VRS+ > 2.0V
VSENSE = 100mV,
VCC = 12V, VRS+ = 12V
2
MAX
Operating Voltage Range
0.9
30
_______________________________________________________________________________________
1.2
%
V
mV
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
(VRS+ = 0 to 28V, VSENSE = (VRS+ - VRS- ) = 0, VCC = +3.0V to +28V, RL = ∞, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = 25°C.) (Note 1)
PARAMETER
Bandwidth
SYMBOL
BW
Slew Rate
Gain
VCC = 12V
VRS+ = 12V
CLOAD = 15pF
TYP
VSENSE = 100mV
(gain = +20V/V)
2
VSENSE = 100mV
(gain = +50V/V)
1.7
VSENSE = 100mV
(gain = +100V/V)
1.2
VSENSE = 6.25mV (Note 3)
0.5
VSENSE = 20mV to 100mV, CLOAD = 15pF
AV
MAX437_T
MAX437_F
+50
MAX437_H
+100
VSENSE = 10mV to 150mV,
VCC = 12V, IOUT = 2mA,
gain = 20 and 50
OUT Setting Time to 1% of Final
Value
VCC = 12V, VRS+ = 12V,
CLOAD = 15pF
CLOAD
MAX
UNITS
MHz
10
V/µs
+20
TA = TMIN to TMAX
V/V
±5.5
±0.5
TA = +25°C
±2.5
%
VSENSE = 10mV to 150mV,
VCC = 20V, IOUT = 2mA,
gain = 100
Maximum Capacitive Load
MIN
SR
∆AV
Gain Accuracy
CONDITIONS
TA = TMIN to TMAX
5.5
TA = +25°C
±0.5
VSENSE = 6.25mV
to 100mV
400
±2.5
ns
VSENSE = 100mV
to 6.25mV
800
No sustained oscillation
Output Resistance
ROUT
VSENSE = 100mV
Power-Supply Rejection
PSR
VRS+ > 2V, VOUT = 1.6V, VCC = 3V to 28V
1000
66
pF
5
Ω
90
dB
Power-Up Time to 1% of Final
Value
VSENSE = 100mV, CLOAD = 15pF
2
µs
Saturation Recovery Time to 1%
of Final Value
VCC = 12V, VRS+ = 12V, CLOAD = 15pF,
VSENSE = 100mV
1
µs
Reverse Recovery Time to 1%
of Final Value
VCC = 12V, VRS_ = 12V, CLOAD = 15pF,
VSENSE = -100mV to +100mV
1
µs
Note 1:
Note 2:
Note 3:
Note 4:
All devices are 100% production tested at TA = +25°C. 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.
_______________________________________________________________________________________
3
MAX4376/MAX4377/MAX4378
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25°C.)
SUPPLY CURRENT (PER AMPLIFIER)
vs. TEMPERATURE
MAX4376T
0.80
MAX4376H
0.75
0.70
0.65
1.0
1.0
MAX4376F
0.8
MAX4376T
0.6
0.4
0.60
MAX4376F
0.4
0.2
0.0
-0.2
-0.4
MAX4376H
-0.8
0
0.50
10
15
20
25
-1.0
-50
30
-25
0
25
50
75
5
10
MAX4376H
4
3
MAX4376F
2
1
0
MAX4376T
15
20
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
1.0
0.8
TOTAL OUTPUT ERROR (%)
5
MAX4376/7/8 toc04
6
TOTAL OUTPUT ERROR (%)
0
SUPPLY VOLTAGE (V)
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE (VSENSE = 6.25mV)
0.6
0.4
MAX4376H
0.2
0
-0.2
-0.4
-2
-0.6
-3
-0.8
MAX4376F
MAX4376T
-1.0
-4
5
10
15
20
25
5
10
15
20
25
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
GAIN ACCURACY
vs. TEMPERATURE
TOTAL OUTPUT ERROR
vs. TEMPERATURE
MAX4376/7/8 toc06
2.0
1.5
1.0
MAX4376H
MAX4376F
0.5
0
-0.5
0
30
MAX4376T
-1.0
1.0
0.8
TOTAL OUTPUT ERROR (%)
0
GAIN ACCURACY (%)
125
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
-1
100
MAX4376/7/8 toc05
5
0.6
MAX4376F
0.4
30
MAX4376/7/8 toc07
0
MAX4376T
0.2
0
-0.2
MAX4376H
-0.4
-0.6
-1.5
-0.8
-1.0
-2.0
-50
-25
0
25
50
75
TEMPERATURE (°C)
4
MAX4376T
0.6
-0.6
0.2
0.55
0.8
MAX4376/7/8 toc03
MAX4376F
1.2
0.85
1.2
MAX4376/7/8 toc02
0.90
SUPPLY CURRENT (mA)
MAX4376H
0.95
1.4
MAX4376/7/8 toc01
1.00
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE (VSENSE = 100mV)
TOTAL OUTPUT ERROR (%)
SUPPLY CURRENT (PER AMPLIFIER)
vs. SUPPLY VOLTAGE
SUPPLY CURRENT (mA)
MAX4376/MAX4377/MAX4378
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
100
125
-50
-25
0
25
50
75
100 125 150
TEMPERATURE (°C)
_______________________________________________________________________________________
25
30
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
MAX4376/7/8 toc08
5
TOTAL OUTPUT ERROR (%)
4
MAX4376 toc09
MAX4376T
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV TO 100mV)
TOTAL OUTPUT ERROR
vs. FULL-SCALE SENSE VOLTAGE
CL = 15pF
RL =1kΩ
IN
(5mV/div)
3
100mV
95mV
2
MAX4376H
MAX4376F
1
2.0V
0
OUT
(50mV/div)
-1
1.9V
MAX4376T
-2
50
100
VSENSE (mV)
150
200
2µs/div
MAX4376F
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV TO 100mV)
MAX4376 toc10
MAX4376H
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV to 100mV)
CL = 15pF
RL = 2.5kΩ
IN
(5mV/div)
MAX4376 toc11
0
CL = 15pF
RL = 5kΩ
100mV
95mV
IN
(5mV/div)
95mV
5V
OUT
(100mV/div)
100mV
10V
OUT
(200mV/div)
4.75V
9.5V
MAX4376T
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
MAX4376F
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
CL = 15pF
RL = 1kΩ
IN
(45mV/div)
MAX4376 toc13
2µs/div
MAX4376 toc12
2µs/div
CL = 15pF
RL = 2.5kΩ
100mV
6mV
IN
(45mV/div)
100mV
6mV
2V
5V
OUT
(500mV/div)
OUT
(2V/div)
0.3V
0.120V
2µs/div
2µs/div
_______________________________________________________________________________________
5
MAX4376/MAX4377/MAX4378
Typical Operating Characteristics (continued)
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25°C.)
Typical Operating Characteristics (continued)
(VCC = VRS+ = 12V, VSENSE = 100mV, TA = +25°C.)
MAX4376H
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
CL = 15pF
RL = 5kΩ
IN
(45mV/div)
45
MAX4376H
40
100mV
35
6mV
10V
GAIN (dB)
30
OUT
(3V/div)
MAX4376/7/8 toc15
SMALL-SIGNAL GAIN
vs. FREQUENCY
MAX4376 toc14
MAX4376F
25
MAX4376T
20
15
10
0.6V
5
0
1.E+04
2µs/div
1.E+05
1.E+06
1.E+07
FREQUENCY (Hz)
OVERDRIVE RESPONSE
AV = +20V/V
OUTPUT LOW
vs. TEMPERATURE
MAX4376/7/8 toc16
750mV
IN
(200mV/div)
MAX4376/7/8 toc17
400
350
300
350mV
VOH
OUT
(2V/div)
OUTPUT LOW (mV)
MAX4376/MAX4377/MAX4378
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
250
MAX4376T
200
MAX4376F
150
100
7V
MAX4376H
50
0
TIME (500ns)
-50
-25
0
25
50
75
TEMPERATURE (°C)
6
_______________________________________________________________________________________
100
125
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
PIN
MAX4376
MAX4376
MAX4377
MAX4378
SOT23-5
SO-8
µMAX-8/
SO-8
SO-14/
TSSOP-14
NAME
FUNCTION
Output Voltage. VOUT_ is proportional to the magnitude
of the sense voltage (VRS+ - VRS-). VOUT_ is
approximately zero when VRS - > VRS - + (no phase
reversal).
1
4
1, 7
1, 7, 8, 14
OUT, OUT_
2
3
4
11
GND
Ground
3
1
8
4
VCC
Supply Voltage
4
8
3, 5
3, 5, 10, 12
RS+, RS_+
Power connection to the external sense resistor
5
6
2, 6
2, 6, 9, 13
RS-, RS_-
Load-side connection to the external sense resistor
—
2, 5, 7
—
—
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, β, to give IRGD = β x
I RG1 . Solving I RGD = β x (I LOAD )(R SENSE )/RG1.
Therefore:
VOUT = β x (RGD/RG1)(RSENSE x ILOAD) x amp gain
where amp gain is 2, 5, or 10.
The part’s gain equals (β x RGD / RG1) x amp gain.
N.C.
No Connection. Not internally connected.
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
Therefore:
VOUT = (GAIN)(RSENSE)(ILOAD)
where GAIN = 20 for MAX437_T.
GAIN = 50 for MAX437_F.
GAIN = 100 for MAX437_H.
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
_______________________________________________________________________________________
7
MAX4376/MAX4377/MAX4378
Pin Description
MAX4376/MAX4377/MAX4378
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
Table 1. Recommended Component Values
FULL-SCALE LOAD
CURRENT, ILOAD (A)
CURRENT-SENSE
RESISTOR, RSENSE (mΩ)
0.1
1000
1
100
5
20
10
10
RSENSE
VSOURCE
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
100
5.0
10.0
ILOAD
TO LOAD BATTERY
RSENSE
0 TO +28V
RS+
BATTERY
RS-
+3V TO +28V
IRG1
+3V TO +28V
FULL-SCALE OUTPUT VOLTAGE
(FULL-SCALE VSENSE = 100 mV),
VOUT (V)
GAIN (+V/V)
RG1
VCC
RG2
SYSTEM
AND
CHARGER
VCC
RS1+
A1
OUT1
RS1-
MAX4376
CURRENT
MIRROR
OUT
IRGD
VOUT
MAX4377
AV = 2, 5,
OR 10
OUT
RS2RGD
OUT2
GND
RS2+
Figure 1. Functional Diagram
monitor. This is useful for implementing either smart
battery packs or fuel gauges.
Current Source Circuit
Figure 2. Bidirectional Current Monitor
Figure 3 shows a block diagram using the MAX4376
with a switching regulator to make a current source.
8
_______________________________________________________________________________________
Single/Dual/Quad High-Side Current-Sense
Amplifiers with Internal Gain
MAX1745
LOW-COST
SWITCHING
REGULATOR
ILOAD
VSENSE
0 TO +18V
TRANSISTOR COUNT: MAX4376_: 162
MAX4377_: 324
MAX4378_: 648
PROCESS: BiCMOS
RSENSE
RS+
VCC
+3V TO +28V
RS-
0.1µF
MAX4376
LOAD/
BATTERY
OUT
GND
Figure 3. Current Source
Pin Configurations (continued)
TOP VIEW
VCC 1
8
RS+
OUT1 1
7
N.C.
RS1- 2
8
VCC
OUT1 1
7
OUT2
RS1- 2
RS1+
N.C.
2
GND
3
6
RS-
RS1+
3
6
RS2-
OUT 4
5
N.C.
GND
4
5
RS2+
MAX4376
SO
MAX4377
14 OUT4
MAX4378
13 RS4-
3
12 RS4+
VCC 4
11 GND
RS2+ 5
10 RS3+
RS2- 6
9
RS3-
7
8
OUT3
µMAX/SO
OUT2
SO/TSSOP
Ordering Information (continued)
GAIN
(+V/+V)
TEMP.
RANGE
MAX4377 T AUA
20
-40°C to +125°C
8 µMAX
—
MAX4377FAUA
50
-40°C to +125°C
8 µMAX
—
MAX4377HAUA
100
-40°C to +125°C
8 µMAX
—
MAX4377TASA
20
-40°C to +125°C
8 SO
—
MAX4377FASA
50
-40°C to +125°C
8 SO
—
MAX4377HASA
100
-40°C to +125°C
8 SO
—
MAX4378 T AUD
20
-40°C to +125°C
14 TSSOP
—
PART
PINPACKAGE
TOP
MARK
MAX4378FAUD
50
-40°C to +125°C
14 TSSOP
—
MAX4378HAUD
100
-40°C to +125°C
14 TSSOP
—
MAX4378TASD
20
-40°C to +125°C
14 SO
—
MAX4378FASD
50
-40°C to +125°C
14 SO
—
MAX4378HASD
100
-40°C to +125°C
14 SO
—
Typical Operating Circuit
ILOAD
VSENSE
0 TO +28V
RSENSE
+3V TO +28V
RS+
RS-
VCC
0.1µF
MAX4376T/F/H
A/D
CONVERTER
LOAD/
BATTERY
OUT
GND
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.
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Printed USA
is a registered trademark of Maxim Integrated Products.
MAX4376/MAX4377/MAX4378
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