Maxim MAX4070ATA Bidirectional, high-side, current-sense amplifiers with reference Datasheet

19-2423; Rev 3; 11/08
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
The MAX4069–MAX4072 low-cost, bidirectional, highside, 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
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 100µA Supply Current
♦ 10µA Supply Current in Shutdown
♦ Available in Space-Saving Packages
8-Pin Thin QFN (MAX4070/MAX4071/MAX4072)
8-Pin µMAX (MAX4070/MAX4071MAX4072)
10-Pin µMAX (MAX4069)
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
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*
MAX4071AUA
-40°C to +125°C 8 µMAX
MAX4071ATA
-40°C to +125°C 8 Thin QFN-EP*
MAX4072AUA
-40°C to +125°C 8 µMAX
ABN
—
ABO
—
ABP
Typical Operating Circuit
Motor Control
FROM BATTERY
CHARGER
Power-Management Systems
Cell-Phone Battery-Current Monitoring
—
MAX4072ATA
-40°C to +125°C 8 Thin QFN-EP*
*EP = Exposed pad.
Smart-Battery Packs/Chargers
TOP
MARK
—
RSENSE
VBATT = 1.35V TO 24V
RS-
VCC = 3.6V TO 24V
RS+
LOAD
VCC
MAX4070
GSEL
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations and Selector Guide appear at end of
data sheet.
OUT
SHDN
REFOUT
TO ADC
2.5V
GND
________________________________________________________________ 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.
1
MAX4069–MAX4072
General Description
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ABSOLUTE MAXIMUM RATINGS
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 4.5 mW/°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
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+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = 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)
PARAMETER
SYMBOL
CONDITIONS
MIN
24
MAX4070
3.6
24
VCC
Input-Referred Offset Voltage
(Note 5)
VOS
Common-Mode Input Range
CMVR
Guaranteed by CMRR test
1.35
Common-Mode Rejection Ratio
CMRR
1.35V ≤ VRS+ = VRS- ≤ 24V, VCC = 12V
100
ICC
VCC = VRS+ = VRS- = 24V, RL = open,
TA = TMIN to TMAX
Shutdown Supply Current
ICC SHDN
Leakage Current
Input Bias Current
Recommended Full-Scale Sense
Voltage (Note 6)
2
VCC = VRS+ =
VRS- = 12V
TA = +25°C
0.08
TA = -40°C to +85°C
TA = TMIN to TMAX
VSENSE
UNITS
V
0.25
0.8
mV
1
24
120
100
V
dB
250
µA
VCC = VRS+ = VRS- = 5.5V,
SHDN = GND, TA = +25°C
9
VCC = VRS+ = VRS- = 24V,
SHDN = GND
10
30
0.1
0.5
µA
2.4
5
µA
µA
VRS+ = VRS- = 24V, VCC = 0V
IRS+, IRS-
MAX
2.7
Operating Voltage Range
(Note 3)
Supply Current
TYP
MAX4069/MAX4071/MAX4072 (Note 4)
VCC = VRS+ = VRS- = 24V
0
Gain = 50V/V
75
Gain = 100V/V
50
_______________________________________________________________________________________
mV
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = 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)
PARAMETER
Total OUT Voltage Error (Note 7)
SYMBOL
CONDITIONS
VSENSE = 75mV,
VCC = VRS+ = 12V,
gain = 50
TA = +25°C
VSENSE = 50mV,
VCC = VRS+ = 12V,
gain = 100
TA = +25°C
MAX4069/MAX4070/
MAX4072:
VSENSE = -35mV,
VCC = VRS+ = 12V,
gain = 50
TA = +25°C
MAX4069/MAX4070/
MAX4072:
VSENSE = -17.5mV,
VCC = VRS+ = 12V,
gain = 100
TA = +25°C
MAX4071:
VSENSE = -15mV,
VCC = VRS+ = 12V,
gain = 50
TA = +25°C
MAX4071:
VSENSE = -7.5mV,
VCC = VRS+ = 12V,
gain = 100
TA = +25°C
VSENSE = 3mV,
VCC = 12V, VRS+ = 12V
MIN
TYP
MAX
±0.25
±1.0
TA = -40°C to +85°C
±1.5
TA = TMIN to TMAX
±2.0
±0.25
±1.0
TA = -40°C to +85°C
±1.5
TA = TMIN to TMAX
±2.5
±0.4
±1.0
TA = -40°C to +85°C
±2.0
TA = TMIN to TMAX
±3.0
±0.8
±2.0
TA = -40°C to +85°C
±4.0
TA = TMIN to TMAX
±6
±1.0
±4.0
TA = TMIN to TMAX
±6.0
±5
TA = -40°C to +85°C
±10
TA = TMIN to TMAX
±15
TA = +25°C
%
±2.5
TA = -40°C to +85°C
±2.0
UNITS
±3
_______________________________________________________________________________________
3
MAX4069–MAX4072
ELECTRICAL CHARACTERISTICS (continued)
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ELECTRICAL CHARACTERISTICS (continued)
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = 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)
PARAMETER
SYMBOL
CONDITIONS
IOUT = 10µA,
VSENSE = 100mV,
VRS+ = VCC
OUT Voltage High
IOUT = -10µA,
VSENSE = -100mV,
VRS+ = VCC
IOUT = -500µA,
VSENSE = -100mV,
VRS+ = VCC
BW
Gain
AV
MAX
MAX4071,
VCC = 2.7V
65
150
MAX4069/MAX4070/
MAX4072,
VCC = 3.6V
65
150
MAX4071,
VCC = 2.7V
90
250
MAX4069/MAX4070/
MAX4072,
VCC = 3.6V
90
250
MAX4071,
VCC = 2.7V
5
20
MAX4069/MAX4070/
MAX4072,
VCC = 3.6V
5
20
MAX4071,
VCC = 2.7V
100
250
MAX4069/MAX4070/
MAX4072,
VCC = 3.6V
100
250
Gain = 50V/V
VSENSE = 50mV,
VCC = 12V, CL = 100pF Gain = 100V/V
100
GSEL = GND
50
GSEL = VCC
100
Logic Low Voltage (GSEL, SHDN)
Logic High Voltage (GSEL, SHDN)
PSRR
VIL
VCC = 3.6V or 24V
VIH
VCC = 3.6V or 24V
Gain-Select Input Current
IGSEL
Shutdown Input Current
ISHDN
4
VCC = 2.7V to 24V
(MAX4069/MAX4071/MAX4072),
VCC = 3.6V to 24V (MAX4070)
GSEL = VCC = 24V or GND
SHDN = VCC = 24V
SHDN = GND, VCC = 24V
kHz
40
Capacitive-Load Stability
Power-Supply Rejection Ratio
UNITS
mV
VOL
-3dB Bandwidth
TYP
mV
VCC - VOH
IOUT = 500µA,
VSENSE = 100mV,
VRS+ = VCC
OUT Voltage Low
MIN
100
V/V
100
pF
120
dB
0.6
V
0.01
1
µA
3
12
0.01
1
2
V
_______________________________________________________________________________________
µA
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
(VRS+ = VRS- = VCC = 2.7V to 24V, VSENSE = VRS+ - VRS- = 0V, IREFOUT = 0, V SHDN = 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)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
TA = +25°C
2.44
2.49
2.54
TA = TMIN to TMAX
2.39
UNITS
REFOUT (MAX4069/MAX4070/MAX4071)
MAX4069,
VCC = 12V
(Note 2)
Reference Output Voltage
Reference Output Voltage
Temperature Coefficient
VREF
TCVREF
Load Regulation
ΔVREFOUT
/ΔIREF
Line Regulation
ΔVREF/
ΔVCC
MAX4070,
VCC = 12V
TA = +25°C
2.45
TA = TMIN to TMAX
2.40
MAX4071,
VCC = 12V
TA = +25°C
1.47
TA = TMIN to TMAX
1.44
VCC = 12V
VADJ
Reference Adjust Input Current
IADJ
2.55
V
2.60
1.5
1.53
1.56
-40°C ≤ TA ≤ +85°C
15
20
ppm/°C
IREFOUT = 0 to 500µA
2
IREFOUT = 0 to -100µA
4
2.7V ≤ VCC ≤ 24V
20
µV/V
500
pF
1.230
V
VADJ to
+4
V
100
nA
MAX4069, VCC = 12V
MAX4069, range adjustable with R1 and R2,
VCC = 12V
Reference Output Voltage Range
2.5
TA = TMIN to TMAX
REF Capacitive-Load Stability
Reference Adjust Voltage
Threshold
2.59
MAX4069, VCC = 12V, VADJ = 1.23V
mV/mA
REFIN (MAX4072 only)
Input-Voltage Range
VCC = 12V
Input Current
REFIN = 2.5V, VCC = 12V
1
4
V
-60
+20
µA
All devices are 100% tested at TA = +25°C. Limits over temperature are guaranteed by design.
R1 = 215kΩ, R2 = 210kΩ for the MAX4069 only (see Functional Diagram). This sets REFOUT to 2.49V nominal.
Guaranteed by the PSRR test.
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).
Note 1:
Note 2:
Note 3:
Note 4:
_______________________________________________________________________________________
5
MAX4069–MAX4072
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.)
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
15
10
0
-25
-50
5
-75
-100
0
-125
-150
-50
-25
0
0.1
0
-0.1
VSENSE = 50mV
AV = 100V/V
-0.2
-0.3
75
100
125
0
TOTAL ERROR vs. TEMPERATURE
1.5
MAX4069-72 toc05
1.0
0.5
AV = 100V/V
0
-0.5
1.0
0
VCC = 12V
-0.5
-1.0
-1.5
2
10 12 14 16 18 20 22 24
8
VCC = 24V
0.5
AV = 50V/V
-2.0
-0.5
6
VSENSE = 50mV
AV = 100V/V
-1.0
-1.5
4
25 50 75 100 125 150 175 200 225 250
VSENSE (V)
1.5
-0.4
6
10
14
18
22
-50
-25
0
25
50
75
100
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
MAX4069
REFOUT vs. TEMPERATURE
110
MAX4070
100
MAX4069
90
MAX4072
80
160
1.245
REFOUT CONNECTED TO ADJ
1.240
140
125
MAX4069-72 toc09
120
AV = 50V/V
1.235
REFOUT (V)
MAX4071
1.250
MAX4069-72 toc08
130
180
SUPPLY CURRENT (μA)
AV = 100V/V
MAX4069-72 toc07
SUPPLY VOLTAGE (V)
140
VCC = 24V
120
100
VCC = 12V
80
1.230
1.225
1.220
1.215
1.210
70
60
60
40
2
4
6
8 10 12 14 16 18 20 22 24
SUPPLY VOLTAGE (V)
6
50
TOTAL ERROR (%)
0.2
25
2.0
MAX4069-72 toc04
VSENSE = 75mV
AV = 50V/V
AV = 50V/V
TOTAL ERROR vs. SUPPLY VOLTAGE
(VSENSE = 3mV)
TOTAL ERROR (%)
TOTAL ERROR (%)
0.3
4
3
TEMPERATURE (°C)
TOTAL ERROR vs. SUPPLY VOLTAGE
0.4
AV = 100V/V
8
7
6
5
2
1
0
VOS (μV)
0.5
10
9
MAX4069-72 toc03
75
50
25
MAX4069-72 toc06
20
AV = 100V/V
125
100
12
11
(VOUT - VREF) (V)
25
-200
-160
-120
-80
-40
0
40
80
120
160
200
PERCENTAGE OF UNITS (%)
30
(VOUT - VREF) vs. VSENSE
150
INPUT OFFSET VOLTAGE (μV)
MAX4069-72 toc01
35
MAX4069-72 toc02
INPUT OFFSET VOLTAGE DISTRIBUTION
SUPPLY CURRENT (μA)
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
1.205
1.200
-50
-25
0
25
50
75
TEMPERATURE (°C)
100
125
-50
-25
0
25
50
75
TEMPERATURE (°C)
_______________________________________________________________________________________
100
125
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
MAX4070
REFOUT vs. TEMPERATURE
1.515
1.233
1.231
1.229
2.465
2.450
1.505
1.500
1.495
-25
0
25
50
75
100
1.485
1.219
1.480
1.217
125
1.215
-50
-25
0
25
50
75
100
MAX4070
REFOUT vs. SUPPLY VOLTAGE
MAX4071
REFOUT vs. SUPPLY VOLTAGE
1.501
2.496
2.495
2.494
2.493
8 10 12 14 16 18 20 22 24
160
1.500
140
1.499
120
1.498
VOH = VCC - VOUT
180
IL = 500μA
100
80
60
1.497
2.492
40
1.496
1.495
2.490
6
0
2
8 10 12 14 16 18 20 22 24
6
10
14
18
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
VOL vs. TEMPERATURE
SMALL-SIGNAL GAIN
vs. FREQUENCY
5
MAX4069-72 toc16
250
225
200
22
-50
0
GAIN (dB)
150
IL = 500μA
125
100
AV = 50V/V
-10
AV = 100V/V
75
0
25
50
75
125
100
PSRR AND CMRR vs. FREQUENCY
175
-5
-25
TEMPERATURE (°C)
0
-20
PSRR AND CMRR (dB)
4
MAX4069-72 toc17
2
IL = 10μA
20
MAX4069-72 toc18
2.491
VOL (mV)
6
VOH vs. TEMPERATURE
VOH (mV)
REFOUT (V)
2.497
4
200
MAX4069-72 toc14
1.502
MAX4069-72 toc13
2.498
2
125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
2.499
1.223
1.221
TEMPERATURE (°C)
2.500
1.225
1.490
1.475
-50
1.227
MAX4069-72 toc15
2.495
REFOUT (V)
REFOUT (V)
2.510
MAX4069-72 toc12
1.520
1.510
2.480
REFOUT (V)
1.235
MAX4069-72 toc11
2.525
REFOUT (V)
1.525
MAX4069-72 toc10
2.540
MAX4069
REFOUT vs. SUPPLY VOLTAGE
MAX4071
REFOUT vs. TEMPERATURE
-40
CMRR
-60
-80
-100
PSRR
-15
50
-120
IL = 10μA
25
-20
0
-50
-25
0
25
50
75
TEMPERATURE (°C)
100
125
-140
0.1
1
10
FREQUENCY (kHz)
100
1000
0.01
0.1
1
10
100
FREQUENCY (Hz)
_______________________________________________________________________________________
7
MAX4069–MAX4072
Typical Operating Characteristics (continued)
(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
Amplifiers with Reference
Typical Operating Characteristics (continued)
(VCC = VRS+ = 12V, VSENSE = 50mV for gain of 100V/V and 75mV for gain of 50V/V, TA = +25°C, unless otherwise noted.)
SMALL-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL TRANSIENT RESPONSE
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc20
MAX4069-72 toc21
MAX4069-72 toc19
GAIN = 100
GAIN = 50
GAIN = 50
INPUT
5mV/div
INPUT
5mV/div
OUTPUT
200mV/div
OUTPUT
500mV/div
REF
REF
100μs/div
100μs/div
OUTPUT
2V/div
REF
100μs/div
STARTUP DELAY
LARGE-SIGNAL TRANSIENT RESPONSE
INPUT
50mV/div
EXITING SHUTDOWN
MAX4069-72 toc23
MAX4069-72 toc22
MAX4069-72 toc24
GAIN = 100
INPUT
20mV/div
OUTPUT
2V/div
VCC
10V/div
VSHDN
5V/div
VOUT
5V/div
VOUT
2V/div
VREFOUT
5V/div
VREFOUT
2V/div
REF
100μs/div
8
20μs/div
100μs/div
_______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
PIN
NAME
FUNCTION
MAX4069
MAX4070/
MAX4071
MAX4072
1
1
1
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.
Shutdown Input. Drive SHDN low to select shutdown mode. Connect SHDN
to VCC for normal operation.
SHDN
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
—
8
6
6
OUT
9
7
7
VCC
REFOUT Reference Output Voltage (MAX4069/MAX4070/MAX4071)
Voltage Output. The difference voltage, VOUT - VREF, is proportional to
the voltage difference between RS+ and RS- and indicates the correct
polarity.
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)
Functional Diagram
2.7V TO 24V
LOAD
FROM BATTERY
CHARGER
VCC
RS+
MAX4069
OUT
CSA
RSENSE
TO ADC
RSGAIN SELECT
SHUTDOWN
GSEL
OA
SHDN
VREF
1.23V
REFOUT
R1
ADJ
GND
R2
_______________________________________________________________________________________
9
MAX4069–MAX4072
Pin Description
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Detailed Description
The MAX4069–MAX4072 bidirectional, high-side, current-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 voltage 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 bidirectional 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 current 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 RSto RS+, the current through Q2 and RG2 increases and
the current through Q1 decreases. In this way, the voltages 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).
10
RSENSE
RS+
RS-
RG1
RG2
MAX4069–MAX4072
OUT
A1
Q1
Q2
A2
IOUT
Figure 1. Detailed Input Stage
Applications Information
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 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 V CC 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
measurements by using low-value sense resistors,
which can be paralleled to further increase the currentsense 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 recommended range for the external resistors is: R1 + R2
should be > 20kΩ and < 500kΩ.
______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
RS-
5V
AV = 100
VOUT - VREF
RS+
LOAD
CHARGE
CURRENT
2.5V
VCC
2
CELLS
MAX4069–MAX4072
ICHARGE
RSENSE
IDISCHARGE
MAX4070
GSEL
OUT
TO ADC
-25mV
0
25mV
50mV
VSENSE
SHDN
REFOUT
2.5V
GND
DISCHARGE
CURRENT
-2.5V
Figure 2. Bidirectional Current Monitor
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 fullscale 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 resistor’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 powersource 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
approximately 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 levels, 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 somewhat
better. Low-inductance metal-film resistors are also
available. Instead of being spiral-wrapped round a
______________________________________________________________________________________
11
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Table 1. Recommended Component Values
FULL-SCALE
CURRENT
(A)
0.075
0.05
0.75
0.5
3.75
2.5
7.5
5.0
15.0
10.0
CURRENT-SENSE
RESISTOR (mΩ)
1000
100
20
10
5
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-toback diodes between the differential input, the absolute
maximum of the differential input voltage is 0.3V.
Dynamic Range Considerations
Although the MAX4069–MAX4072 have fully symmetrical, bidirectional, VSENSE input capability, the outputvoltage 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.
GAIN
(V/V)
VSENSE
(mV)
FULL-SCALE OUTPUT
VOLTAGE WITH RESPECT
TO REF (V)
50
75
3.75
100
50
5.0
50
75
3.75
100
50
5.0
3.75
50
75
100
50
5.0
50
75
3.75
100
50
5.0
50
75
3.75
100
50
5.0
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 RSterminal (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 highside 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 systems 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.
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.
12
______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
TOP VIEW
SHDN 1
RS-
2
RS+
3
N.C.
GND
10 GSEL
9
VCC
8
OUT
4
7
REFOUT
5
6
ADJ
MAX4069
SHDN
1
RS-
2
RS+
3
MAX4070
MAX4071
MAX4072
GND 4
μMAX
8
GSEL
7
VCC
6
OUT
5
REFOUT (REFIN)
Thin QFN/μMAX
(REFIN) FOR MAX4072 ONLY.
Selector Guide
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 V SENSE , the Kelvin
method is recommended. The current into RS+ and RSis only a few microamps; therefore, a short distance from
RS+ and RS- pins does not cause significant errors. It is
recommended to keep the value of RSENSE reasonably
higher than the values of the trace’s resistance.
SUPPLY
VOLTAGE
RANGE (V)
COMMONMODE RANGE
(V)
PART
REFERENCE
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
______________________________________________________________________________________
13
MAX4069–MAX4072
Pin Configurations
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
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
6, 8, &10L, DFN THIN.EPS
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
14
______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
COMMON DIMENSIONS
PACKAGE VARIATIONS
SYMBOL
MIN.
MAX.
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
[(N/2)-1] x e
A
0.70
0.80
T633-2
6
1.50±0.10
2.30±0.10
0.95 BSC
MO229 / WEEA
0.40±0.05
1.90 REF
D
2.90
3.10
T833-2
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
E
2.90
3.10
T833-3
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
A1
0.00
0.05
T1033-1
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
L
0.20
0.40
T1033-2
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
k
0.25 MIN.
T1433-1
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 REF
A2
0.20 REF.
T1433-2
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 REF
______________________________________________________________________________________
15
MAX4069–MAX4072
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
8LUMAXD.EPS
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
α
α
16
______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
10LUMAX.EPS
α
α
______________________________________________________________________________________
17
MAX4069–MAX4072
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
MAX4069–MAX4072
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Revision History
REVISION
NUMBER
REVISION
DATE
3
11/08
DESCRIPTION
Added information for RG1 and RG2
PAGES
CHANGED
10
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implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.