General Description
The MAX4069–MAX4072 low-cost, bidirectional, high-
side, 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
●Smart-Battery Packs/Chargers
●Motor Control
●Power-Management Systems
●Cell-Phone Battery-Current Monitoring
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100μASupplyCurrent
● 10μASupplyCurrentinShutdown
●Available in Space-Saving Packages
• 8-Pin Thin QFN (MAX4070/MAX4071/MAX4072)
• 8-PinμMAX(MAX4070/MAX4071/MAX4072)
• 10-PinμMAX(MAX4069)
μMAX is a registered trademark of Maxim Integrated Products,
Inc.
Pin Configurations and Selector Guide appear at end of
data sheet.
19-2423; Rev 4; 11/16
*EP = Exposed pad.
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Ordering Information
Typical Operating Circuit
PART TEMP RANGE PIN-PACKAGE TOP
MARK
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* ADH
MAX4071AUA+ -40°C to +125°C 8 µMAX —
MAX4071ATA+ -40°C to +125°C 8 Thin QFN-EP* ADI
MAX4072AUA+ -40°C to +125°C 8 µMAX —
MAX4072ATA+ -40°C to +125°C 8 Thin QFN-EP* ADJ
MAX4070
VBATT = 1.35V TO 24V
VCC = 3.6V TO 24V
FROM BATTERY
CHARGER
RSENSE
LOAD
TO ADC
2.5V
VCC
GSEL
GND
RS- RS+
REFOUT
OUT
SHDN
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 4.5mW/°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
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = 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)
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
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Absolute Maximum Ratings
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
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range
(Note 3) VCC
MAX4069/MAX4071/MAX4072 (Note 4) 2.7 24 V
MAX4070 3.6 24
Input-Referred Offset Voltage
(Note 5) VOS
VCC = VRS+ =
VRS- = 12V
TA = +25°C 0.08 0.25
mVTA = -40°C to +85°C 0.8
TA = TMIN to TMAX 1
Common-Mode Input Range CMVR Guaranteed by CMRR test 1.35 24 V
Common-Mode Rejection Ratio CMRR 1.35V≤VRS+ = VRS-≤24V,VCC = 12V 100 120 dB
Supply Current ICC
VCC = VRS+ = VRS- = 24V, RL = open,
TA = TMIN to TMAX
100 250 µA
Shutdown Supply Current ICC SHDN
VCC = VRS+ = VRS- = 5.5V,
SHDN = GND, TA = +25°C 9
µA
VCC = VRS+ = VRS- = 24V,
SHDN = GND 10 30
Leakage Current VRS+ = VRS- = 24V, VCC = 0V 0.1 0.5 µA
Input Bias Current IRS+, IRS- VCC = VRS+ = VRS- = 24V 0 2.4 5 µA
Recommended Full-Scale Sense
Voltage (Note 6) VSENSE
Gain = 50V/V 75 mV
Gain = 100V/V 50
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = 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)
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Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Total OUT Voltage Error (Note 7)
VSENSE = 75mV,
VCC = VRS+ = 12V,
gain = 50
TA = +25°C ±0.25 ±1.0
%
TA = -40°C to +85°C ±1.5
TA = TMIN to TMAX ±2.0
V
SENSE
= 50mV,
V
CC
= V
RS+
= 12V,
gain = 100
TA = +25°C ±0.25 ±1.0
TA = -40°C to +85°C ±1.5
TA = TMIN to TMAX ±2.5
MAX4069/MAX4070/
MAX4072:
V
SENSE
= -35mV,
V
CC
= V
RS+
= 12V,
gain = 50
TA = +25°C ±0.4 ±1.0
TA = -40°C to +85°C ±2.0
TA = TMIN to TMAX ±3.0
MAX4069/MAX4070/
MAX4072:
V
SENSE
= -17.5mV,
V
CC
= V
RS+
= 12V,
gain = 100
T
A
= +25°C ±0.8 ±2.0
T
A
= -40°C to +85°C ±4.0
T
A
= T
MIN
to T
MAX
±6
MAX4071:
V
SENSE
= -15mV,
V
CC
= V
RS+
= 12V,
gain = 50
T
A
= +25°C ±1.0 ±2.5
T
A
= -40°C to +85°C ±4.0
T
A
= T
MIN
to T
MAX
±6.0
MAX4071:
V
SENSE
= -7.5mV,
V
CC
= V
RS+
= 12V,
gain = 100
T
A
= +25°C ±2.0 ±5
T
A
= -40°C to +85°C ±10
T
A
= T
MIN
to T
MAX
±15
V
SENSE
= 3mV,
V
CC
= 12V,
V
RS+
= 12V
T
A
= +25°C ±3
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = 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)
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
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Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
OUT Voltage High V
CC
- V
OH
I
OUT
= 10µA,
V
SENSE
= 100mV,
V
RS+
= V
CC
MAX4071,
V
CC
= 2.7V 65 150
mV
MAX4069/MAX4070/
MAX4072,
V
CC
= 3.6V
65 150
I
OUT
= 500µA,
V
SENSE
= 100mV,
V
RS+
= V
CC
MAX4071,
V
CC
= 2.7V 90 250
MAX4069/MAX4070/
MAX4072,
V
CC
= 3.6V
90 250
OUT Voltage Low V
OL
I
OUT
= -10µA,
V
SENSE
= -100mV,
V
RS+
= V
CC
MAX4071,
V
CC
= 2.7V 5 20
mV
MAX4069/MAX4070/
MAX4072,
V
CC
= 3.6V
5 20
I
OUT
= -500µA,
V
SENSE
= -100mV,
V
RS+
= V
CC
MAX4071,
V
CC
= 2.7V 100 250
MAX4069/MAX4070/
MAX4072,
V
CC
= 3.6V
100 250
-3dB Bandwidth BW
V
SENSE
= 50mV,
V
CC
= 12V,
C
L
= 100pF
Gain = 50V/V 100
kHz
Gain = 100V/V 40
Gain A
V
GSEL = GND 50 V/V
GSEL = V
CC
100
Capacitive-Load Stability 100 pF
Power-Supply Rejection Ratio PSRR
V
CC
= 2.7V to 24V
(MAX4069/MAX4071/MAX4072),
V
CC
= 3.6V to 24V (MAX4070)
100 120 dB
Logic Low Voltage (GSEL, SHDN)V
IL
V
CC
= 3.6V or 24V 0.6 V
Logic High Voltage (GSEL, SHDN)V
IH
V
CC
= 3.6V or 24V 2 V
Gain-Select Input Current I
GSEL
GSEL = V
CC
= 24V or GND 0.01 1 µA
Shutdown Input Current I
SHDN
SHDN = V
CC
= 24V 3 12 µA
SHDN = GND, V
CC
= 24V 0.01 1
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, VSHDN = 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)
Note 1: All devices are 100% tested at TA = +25°C. Limits over temperature are guaranteed by design.
Note 2: R1=215kΩ,R2=210kΩfortheMAX4069only(seeFunctional Diagram). This sets REFOUT to 2.49V nominal.
Note 3: Guaranteed by the PSRR test.
Note 4: 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).
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
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Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
REFOUT (MAX4069/MAX4070/MAX4071)
Reference Output Voltage V
REF
MAX4069,
V
CC
= 12V
(Note 2)
T
A
= +25°C 2.44 2.49 2.54
V
T
A
= T
MIN
to T
MAX
2.39 2.59
MAX4070,
V
CC
= 12V
T
A
= +25°C 2.45 2.5 2.55
T
A
= T
MIN
to T
MAX
2.40 2.60
MAX4071,
V
CC
= 12V
T
A
= +25°C 1.47 1.5 1.53
T
A
= T
MIN
to T
MAX
1.44 1.56
Reference Output Voltage
TemperatureCoefcient TCV
REF
V
CC
= 12V -40°C≤T
A
≤+85°C 15 ppm/°C
T
A
= T
MIN
to T
MAX
20
Load Regulation ∆V
REFOUT
/∆I
REF
I
REFOUT
= 0 to 500µA 2 mV/mA
I
REFOUT
= 0 to -100µA 4
Line Regulation ∆V
REF
/
∆V
CC
2.7V≤V
CC
≤24V 20 µV/V
REF Capacitive-Load Stability 500 pF
Reference Adjust Voltage
Threshold V
ADJ
MAX4069, V
CC
= 12V 1.230 V
Reference Output Voltage Range MAX4069, range adjustable with R1 and
R2, V
CC
= 12V
V
ADJ
to +4 V
Reference Adjust Input Current I
ADJ
MAX4069, V
CC
= 12V, V
ADJ
= 1.23V 100 nA
REFIN (MAX4072 ONLY)
Input-Voltage Range V
CC
= 12V 1 4 V
Input Current REFIN = 2.5V, V
CC
= 12V -60 +20 µA
(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
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Typical Operating Characteristics
INPUT OFFSET VOLTAGE DISTRIBUTION
MAX4069-72 toc01
VOS (µV)
PERCENTAGE OF UNITS (%)
160
120
80
40
0
-40
-80
-120
5
10
15
20
25
0
-160
200
-200
30
35
TOTAL ERROR vs. SUPPLY VOLTAGE
MAX4069-72 toc04
SUPPLY VOLTAGE (V)
TOTAL ERROR (%)
222016 188 10 12 146
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
4 24
VSENSE = 75mV
AV = 50V/V
VSENSE = 50mV
AV = 100V/V
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4069-72 toc07
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
22204 6 8 12 14 1610 18
70
80
90
100
110
120
130
140
60
2 24
AV = 100V/V
MAX4071
MAX4070
MAX4069
MAX4072
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX4069-72 toc02
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (µV)
1007525 500-25
-125
-100
-75
0
25
50
75
100
125
150
-150
-50 125
-50
-25
AV = 100V/V
TOTAL ERROR vs. SUPPLY VOLTAGE
(VSENSE = 3mV)
MAX4069-72 toc05
SUPPLY VOLTAGE (V)
TOTAL ERROR (%)
18146 10
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
2 22
AV = 100V/V
AV = 50V/V
SUPPLY CURRENT vs. TEMPERATURE
MAX4069-72 toc08
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
1007550250-25
60
80
100
120
140
160
180
40
-50 125
AV = 50V/V
VCC = 24V
VCC = 12V
(VOUT - VREF) vs. VSENSE
MAX4069-72 toc03
VSENSE (V)
(V
OUT
- V
REF
) (V)
225200150 17550 75 100 12525
1
2
3
4
5
6
7
8
9
10
11
12
0
0 250
AV = 100V/V
AV = 50V/V
TOTAL ERROR vs. TEMPERATURE
MAX4069-72 toc06
TEMPERATURE (°C)
TOTAL ERROR (%)
1007550250-25
-1.0
-0.5
0
0.5
1.0
1.5
-1.5
-50 125
VSENSE = 50mV
AV = 100V/V
VCC = 24V
VCC = 12V
MAX4069
REFOUT vs. TEMPERATURE
MAX4069-72 toc09
TEMPERATURE (°C)
REFOUT (V)
1007525 500-25
1.205
1.210
1.215
1.220
1.225
1.230
1.235
1.240
1.245
1.250
1.200
-50 125
REFOUT CONNECTED TO ADJ
(VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.)
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Typical Operating Characteristics (continued)
MAX4070
REFOUT vs. TEMPERATURE
MAX4069-72 toc10
TEMPERATURE (°C)
REFOUT (V)
1007550250-25
2.465
2.480
2.495
2.510
2.525
2.540
2.450
-50 125
MAX4070
REFOUT vs. SUPPLY VOLTAGE
MAX4069-72 toc13
SUPPLY VOLTAGE (V)
REFOUT (V)
222016 186 8 10 12 144
2.491
2.492
2.493
2.494
2.495
2.496
2.497
2.498
2.499
2.500
2.490
2 24
VOL vs. TEMPERATURE
MAX4069-72 toc16
TEMPERATURE (°C)
V
OL
(mV)
1007525 500-25
25
50
75
100
125
150
175
200
225
250
0
-50 125
IL = 500µA
IL = 10µA
MAX4071
REFOUT vs. TEMPERATURE
MAX4069-72 toc11
TEMPERATURE (°C)
REFOUT (V)
1007525 500-25
1.480
1.485
1.490
1.495
1.500
1.505
1.510
1.515
1.520
1.525
1.475
-50 125
MAX4071
REFOUT vs. SUPPLY VOLTAGE
MAX4069-72 toc14
SUPPLY VOLTAGE (V)
REFOUT (V)
1814106
1.496
1.497
1.498
1.499
1.500
1.501
1.502
1.495
2 22
SMALL-SIGNAL GAIN
vs. FREQUENCY
MAX4069-72 toc17
FREQUENCY (kHz)
GAIN (dB)
100101
-15
-10
-5
0
5
-20
0.1 1000
AV = 50V/V
AV = 100V/V
MAX4069
REFOUT vs. SUPPLY VOLTAGE
MAX4069-72 toc12
SUPPLY VOLTAGE (V)
REFOUT (V)
222016 186 8 10 12 144
1.217
1.219
1.221
1.223
1.225
1.227
1.229
1.231
1.233
1.235
1.215
2 24
VOH vs. TEMPERATURE
MAX4069-72 toc15
TEMPERATURE (°C)
V
OH
(mV)
1007525 500-25
20
40
60
80
100
120
140
160
180
200
0
-50 125
VOH = VCC - VOUT
IL = 500µA
IL = 10µA
0
-140
0.01 1 100.1 100
PSRR AND CMRR vs. FREQUENCY
MAX4069-72 toc18
FREQUENCY (Hz)
PSRR AND CMRR (dB)
-100
-80
-60
-40
-20
-120
CMRR
PSRR
(VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.)
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Typical Operating Characteristics (continued)
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc19
100µs/div
OUTPUT
200mV/div
REF
INPUT
5mV/div
GAIN = 50
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc20
100µs/div
OUTPUT
500mV/div
REF
INPUT
5mV/div
GAIN = 100
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc21
100µs/div
OUTPUT
2V/div
INPUT
50mV/div
GAIN = 50
REF
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc22
100µs/div
OUTPUT
2V/div
INPUT
20mV/div
GAIN = 100
REF
STARTUP DELAY
MAX4069-72 toc23
20µs/div
VREFOUT
5V/div
VOUT
5V/div
VCC
10V/div
EXITING SHUTDOWN
MAX4069-72 toc24
100µs/div
VREFOUT
2V/div
VOUT
2V/div
VSHDN
5V/div
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Pin Description
Functional Diagram
MAX4069
RS+
RS-
GSEL
SHDN
2.7V TO 24V
VCC
OUT TO ADC
R1
R2
SHUTDOWN
GAIN SELECT
RSENSE
LOAD
FROM BATTERY
CHARGER
REFOUT
OA
ADJ
GND
VREF
1.23V
CSA
PIN
NAME FUNCTION
MAX4069 MAX4070/
MAX4071 MAX4072
1 1 1 SHDN Shutdown Input. Drive SHDN low to select shutdown mode. Connect SHDN
to VCC for normal operation.
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.
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 — REFOUT Reference Output Voltage (MAX4069/MAX4070/MAX4071)
8 6 6 OUT
Voltage Output. The difference voltage, VOUT - VREF, is proportional to
the voltage difference between RS+ and RS- and indicates the correct
polarity.
9 7 7 VCC 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)
Detailed Description
The MAX4069–MAX4072 bidirectional, high-side, cur-
rent-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 volt-
age 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 bidi-
rectional 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 cur-
rent 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 RS-
to RS+, the current through Q2 and RG2 increases and
the current through Q1 decreases. In this way, the volt-
ages 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).
Applications Information
Bidirectional, Current-Sense Amplier
Systems such as laptop computers and other devices that
have internal charge circuitry require a precise bidirec-
tional, 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 VCC
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 mea-
surements by using low-value sense resistors, which can
be paralleled to further increase the current-sense 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rec-
ommended range for the external resistors is: R1 + R2
should be > 20kΩand<500kΩ.
Figure 1. Detailed Input Stage
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Ampliers with Reference
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MAX4069–MAX4072
RSENSE
RS-RS+
RG2RG1
A1
A2
Q1 Q2
IOUT
OUT
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 full-scale
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 resis-
tor’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 power-
source 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 approxi-
mately 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 lev-
els, 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 some-
what better. Low-inductance metal-film resistors are
also available. Instead of being spiral-wrapped round a
Figure 2. Bidirectional Current Monitor
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Ampliers with Reference
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MAX4070
IDISCHARGE RSENSE
ICHARGE
LOAD
TO ADC
2.5V
VCC
GSEL
GND
RS- RS+
REFOUT
OUT
SHDN
2
CELLS
-25mV 25mV 50mV0
DISCHARGE
CURRENT
CHARGE
CURRENT
-2.5V
5V
2.5V
AV = 100
VOUT - VREF
VSENSE
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-to-back
diodes between the differential input, the absolute maxi-
mum of the differential input voltage is 0.3V.
Dynamic Range Considerations
Although the MAX4069–MAX4072 have fully symmetri-
cal, bidirectional, VSENSE input capability, the output-volt-
age 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.
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.
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 RS- terminal (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 high-
side 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 sys-
tems 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.
Table 1. Recommended Component Values
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Ampliers with Reference
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│
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FULL-SCALE
CURRENT
(A)
CURRENT-SENSE
RESISTOR (mΩ)
GAIN
(V/V)
VSENSE
(mV)
FULL-SCALE OUTPUT
VOLTAGE WITH RESPECT
TO REF (V)
0.075 1000 50 75 3.75
0.05 100 50 5.0
0.75 100 50 75 3.75
0.5 100 50 5.0
3.75 20 50 75 3.75
2.5 100 50 5.0
7.5 10 50 75 3.75
5.0 100 50 5.0
15.0 550 75 3.75
10.0 100 50 5.0
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 VSENSE, the Kelvin method
is recommended. The current into RS+ and RS- is only a
few microamps; therefore, a short distance from RS+ and
RS- pins does not cause significant errors. It is recom-
mended to keep the value of RSENSE reasonably higher
than the values of the trace’s resistance.
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Ampliers with Reference
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Pin Congurations
Selector Guide
1
2
3
4
5
10
9
8
7
6
GSEL
VCC
OUT
REFOUTN.C.
RS+
RS-
MAX4069
µMAX
+
TOP VIEW
ADJGND
SHDN
OUT
REFOUT (REFIN)
(REFIN) FOR MAX4072 ONLY.
GND
1
2
8
7
GSEL
VCC
RS-
RS+
Thin QFN/µMAX
3
4
6
5
MAX4070
MAX4071
MAX4072
SHDN
+
PART REFERENCE
SUPPLY
VOLTAGE
RANGE (V)
COMMON-
MODE RANGE
(V)
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
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
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX4069–MAX4072 Bidirectional, High-Side, Current-Sense
Ampliers with Reference
© 2016 Maxim Integrated Products, Inc.
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14
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
3 11/08 Added information for RG1 and RG2 10
4 11/16 Updated Ordering Information table 1
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