MAX4070AGA [MAXIM]
Power Supply Support Circuit, Fixed, 1 Channel, BICMOS, PQFP8, 3 X 3 MM, MO-220EEC-2, QFN-8;
| 型号： | MAX4070AGA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Support Circuit, Fixed, 1 Channel, BICMOS, PQFP8, 3 X 3 MM, MO-220EEC-2, QFN-8 信息通信管理 |
| 文件： | 总16页 (文件大小：535K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2423; Rev 0; 4/02
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
General Description
Features
ꢀ Bidirectional, Compact, Current-Sense Solution
ꢀ Total Output Error Less than 1.5%
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 fea-
ture 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.
ꢀ 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)
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
1.50V (MAX4071)
ꢀ Low 100µA Supply Current
ꢀ 10µA Supply Current in Shutdown
ꢀ Available in Space-Saving Packages
8-Pin QFN (MAX4070/MAX4071/MAX4072)
8-Pin µMAX (MAX4070/MAX4071MAX4072)
10-Pin µMAX (MAX4069)
from 2.5V to V , while discharge current is given from
CC
2.5V to GND. The MAX4071 is similar, but with a refer-
ence 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.
Ordering Information
PIN-
PACKAGE
TOP
MARK
PART
TEMP RANGE
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 QFN packages. The MAX4069 is
available in a 10-pin µMAX package.
MAX4069AUB
MAX4070AUA
-40°C to +125°C 10 µMAX
-40°C to +125°C 8 µMAX
—
—
MAX4070AGA* -40°C to +125°C 8 QFN
MAX4071AUA -40°C to +125°C 8 µMAX
MAX4071AGA* -40°C to +125°C 8 QFN
MAX4072AUA -40°C to +125°C 8 µMAX
ABN
—
ABO
—
Applications
MAX4072AGA* -40°C to +125°C 8 QFN
*Future product—contact factory for availability.
ABP
Notebook Fuel Gauging
Smart-Battery Packs/Chargers
Motor Control
Typical Operating Circuit
FROM BATTERY
CHARGER
Power-Management Systems
Cell-Phone Battery-Current Monitoring
R
SENSE
V
= 1.35V TO 24V
BATT
Selector Guide
RS-
RS+
LOAD
SUPPLY
VOLTAGE
RANGE (V)
COMMON-
MODE RANGE
(V)
V
= 3.6V TO 24V
V
CC
CC
PART
REFERENCE
MAX4070
MAX4069
MAX4070
MAX4071
MAX4072
ADJUSTABLE
2.5V
2.7 to 24
3.6 to 24
2.7 to 24
2.7 to 24
1.35 to 24
1.35 to 24
1.35 to 24
1.35 to 24
GSEL
OUT
TO ADC
1.5V
SHDN
REFOUT
2.5V
EXTERNAL
GND
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ABSOLUTE MAXIMUM RATINGS
V
, RS+, RS- to GND ...........................................-0.3V to +26V
Continuous Power Dissipation (T = +70°C)
CC
A
OUT to GND....................-0.3V to Lesser of (V
+ 0.3V) or 15V
8-Pin µMAX (derate 4.5 mW/°C above +70°C)............362mW
8-Pin QFN (derate 4.7mW/°C above +70°C) ...............379mW
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
CC
Differential Input Voltage (V
GSEL, SHDN, REFOUT, REFIN
- V ) .............................. 0.3V
RS
-
RS
+
and ADJ to GND.....................................-0.3V to (V
OUT Short-Circuit Duration to GND
+ 0.3V)
CC
or to Lesser of (V
REFOUT Short Circuit to V
or 15V)...................................Continuous
CC
or GND........................Continuous
CC
Current into Any Pin .......................................................... 20mA
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
(V
= V
MIN
= V
= 2.7V to 24V, V
= V
- V
= 0, I
RS
-
= 0, V
= V , V
= GND, V
= 12V.) (Notes 1, 2)
= 2.5V (MAX4072),
REFIN
RS
+
RS
to T
CC
SENSE
RS
REFOUT
A
SHDN
CC GSEL
-
+
T
= T
, unless otherwise noted. Typical values are at T = +25°C and at V
= V
A
MAX
CC
RS
+
PARAMETER
SYMBOL
CONDITIONS
MIN
2.7
TYP
MAX
24
UNITS
MAX4069/MAX4071/MAX4072 (Note 4)
MAX4070
Operating Voltage Range
(Note 3)
V
V
CC
3.6
24
T
A
T
A
T
A
= +25°C
0.08
0.25
0.8
1
Input-Referred Offset Voltage
(Note 5)
V
V
= V
= 12V
=
RS+
CC
V
mV
= -40°C to +85°C
= T to T
OS
RS-
MIN
MAX
Common-Mode Input Range
Common-Mode Rejection Ratio
CMVR
CMRR
Guaranteed by CMRR test
1.35V ≤ V = V ≤ 24V, V = 12V
1.35
100
24
V
120
100
dB
RS+
RS-
CC
V
= V
= V = 24V, R = open,
RS- L
CC
RS+
Supply Current
I
250
µA
µA
CC
T
A
= T to T
MIN MAX
V
= V
= V = 5.5V,
RS-
CC
RS+
9
SHDN = GND, T = +25°C
A
Shutdown Supply Current
I
CC SHDN
V
= V
= V
= 24V,
RS-
CC
RS+
10
30
SHDN = GND
Leakage Current
Input Bias Current
V
V
= V
= 24V, V = 0
CC
0.1
2.4
75
0.5
5
µA
µA
RS+
RS-
I
I
= V
= V = 24V
RS-
0
RS+, RS-
CC
RS+
Gain = 50V/V
Gain = 100V/V
Recommended Full-Scale Sense
Voltage (Note 6)
V
mV
SENSE
50
2
_______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
MIN
= V
= 2.7V to 24V, V
= V
- V
= 0, I
RS
-
= 0, V
= V , V
= GND, V
= 12V.) (Notes 1, 2)
= 2.5V (MAX4072),
REFIN
RS
+
RS
to T
CC
SENSE
RS
REFOUT
SHDN
CC GSEL
-
+
T
= T
, unless otherwise noted. Typical values are at T = +25°C and at V
= V
A
MAX
A
CC
RS
+
PARAMETER
SYMBOL
CONDITIONS
= +25°C
= 75mV,
MIN
TYP
MAX
1.0
1.5
2.0
1.0
1.5
2.5
UNITS
T
A
0.25
V
V
SENSE
= V
= 12V,
T = -40°C to +85°C
A
CC
RS+
gain = 50
T
= T
to T
A
A
MIN MAX
T
= +25°C
0.25
0.4
V
V
= 50mV,
SENSE
= V
= 12V,
T = -40°C to +85°C
A
CC
RS+
gain = 100
T
A
= T to T
MIN MAX
MAX4069/MAX4070/
MAX4072:
T
A
= +25°C
1.0
V
V
= -35mV,
SENSE
T = -40°C to +85°C
2.0
3.0
2.0
A
= V
= 12V,
RS+
CC
T
= T to T
MIN MAX
A
A
gain = 50
MAX4069/MAX4070/
MAX4072:
T
= +25°C
0.8
Total OUT Voltage Error (Note 7)
%
V
V
= -17.5mV,
T = -40°C to +85°C
4.0
6
SENSE
A
= V
= 12V,
RS+
CC
T
A
T
A
= T
to T
gain = 100
MIN MAX
= +25°C
1.0
2.0
2.5
4.0
6.0
5
MAX4071:
V
V
= -15mV,
SENSE
T = -40°C to +85°C
A
= V
= 12V,
RS+
CC
gain = 50
T
= T
to T
A
A
MIN MAX
T
= +25°C
MAX4071:
V
V
= -7.5mV,
SENSE
T = -40°C to +85°C
10
15
A
= V
= 12V,
RS+
CC
gain = 100
T
= T to T
MIN MAX
A
A
V
V
= 3mV,
SENSE
T
= +25°C
3
= 12V, V
= 12V
RS+
CC
_______________________________________________________________________________________
3
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
MIN
= V
= 2.7V to 24V, V
= V
- V
= 0, I
RS
-
= 0, V
= V , V
= GND, V
= 12V.) (Notes 1, 2)
= 2.5V (MAX4072),
REFIN
RS
+
RS
to T
CC
SENSE
RS
REFOUT
SHDN
CC GSEL
-
+
T
= T
, unless otherwise noted. Typical values are at T = +25°C and at V
= V
A
MAX
A
CC
RS
+
PARAMETER
SYMBOL
CONDITIONS
MAX4071,
= 2.7V
MIN
TYP
MAX
UNITS
65
150
V
CC
I
= 10µA,
OUT
V
V
=100mV,
SENSE
MAX4069/MAX4070/
MAX4072,
= V
RS+
CC
65
90
90
5
150
250
250
20
V
= 3.6V
CC
OUT Voltage High
V
- V
OH
mV
CC
MAX4071,
= 2.7V
V
CC
I
= 500µA,
= 100mV,
OUT
V
V
SENSE
MAX4069/MAX4070/
MAX4072,
= V
RS+
CC
V
= 3.6V
CC
MAX4071,
= 2.7V
V
CC
I
= -10µA,
= -100mV,
OUT
V
V
SENSE
MAX4069/MAX4070/
MAX4072,
= V
RS+
CC
5
20
V
= 3.6V
CC
OUT Voltage Low
-3dB Bandwidth
V
mV
OL
MAX4071,
= 2.7V
100
100
250
250
V
CC
I
V
V
= -500µA,
= -100mV,
OUT
SENSE
MAX4069/MAX4070/
MAX4072,
V
= V
RS+
CC
= 3.6V
CC
Gain = 50V/V
Gain = 100V/V
100
40
V
V
= 50mV,
SENSE
BW
kHz
= 12V, C = 100pF
CC
L
GSEL = GND
GSEL = V
50
Gain
A
V/V
pF
V
100
100
CC
Capacitive-Load Stability
V
= 2.7V to 24V
CC
Power-Supply Rejection Ratio
PSRR
(MAX4069/MAX4071/MAX4072),
100
2
120
dB
V
= 3.6V to 24V (MAX4070)
CC
Logic Low Voltage (GSEL, SHDN)
Logic High Voltage (GSEL, SHDN)
Gain-Select Input Current
V
V
V
= 3.6V or 24V
= 3.6V or 24V
0.6
V
V
IL
CC
CC
V
IH
I
GSEL = V
= 24V or GND
CC
0.01
3
1
12
1
µA
GSEL
SHDN = V = 24V
CC
Shutdown Input Current
I
µA
SHDN
SHDN = GND, V = 24V
0.01
CC
4
_______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
MIN
= V
= 2.7V to 24V, V
= V
- V
= 0, I
RS
-
= 0, V
= V , V
= GND, V
= 12V.) (Notes 1, 2)
= 2.5V (MAX4072),
REFIN
RS
+
RS
-
CC
SENSE
RS
+
REFOUT
SHDN
CC GSEL
T
A
= T
to T
, unless otherwise noted. Typical values are at T = +25°C and at V
= V
MAX
A
CC
RS
+
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
REFOUT (MAX4069/MAX4070/MAX4071)
MAX4069,
= 12V
(Note 2)
T
T
= +25°C
2.44
2.39
2.49
2.54
2.59
A
V
CC
= T
to T
MAX
A
MIN
T
A
T
A
T
A
T
A
= +25°C
2.45
2.40
1.47
1.44
2.5
1.5
2.55
2.60
1.53
1.56
Reference Output Voltage
V
V
MAX4070,
REF
V
= 12V
= T
to T
CC
MIN
MAX
= +25°C
= T to T
MAX4071,
V
= 12V
CC
MIN
MAX
-40°C ≤ T ≤ +85°C
15
20
2
A
Reference Output Voltage
Temperature Coefficient
TCV
V
= 12V
ppm/°C
REF
CC
T
= T to T
MIN MAX
A
I
I
= 0 to 500µA
= 0 to -100µA
REFOUT
∆V
/∆I
REFOUT
Load Regulation
mV/mA
REF
4
REFOUT
∆V
∆V
REF/
Line Regulation
2.7V ≤ V
≤ 24V
20
µV/V
pF
V
CC
CC
REF Capacitive-Load Stability
500
Reference Adjust Voltage
Threshold
V
MAX4069, V = 12V
1.230
ADJ
CC
MAX4069, range adjustable with R1 and R2,
= 12V
V
to
ADJ
+4
Reference Output Voltage Range
V
V
CC
Reference Adjust Input Current
REFIN (MAX4072 only)
Input-Voltage Range
Input Current
I
MAX4069, V
= 12V, V = 1.23V
ADJ
100
nA
ADJ
CC
V
= 12V
1
4
V
CC
REFIN = 2.5V, V
= 12V
-60
+20
µA
CC
Note 1: All devices are 100% tested at T = +25°C. Limits over temperature are guaranteed by design.
A
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 V
- 1.1V. Similarly, the maximum REFIN
CC
voltage for the MAX4072 should also be less than V
- 1.1V.
CC
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 V = V - V = 0.
SENSE
RS+
RS-
Note 6: The negative full-scale sense voltage is limited by the voltage range of OUT from V
to GND.
REFOUT
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).
_______________________________________________________________________________________
5
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Typical Operating Characteristics
(V = V
= 12V, V
= 50mV for gain of 100V/V and 75mV for gain of 50V/V, T = +25°C, unless otherwise noted.)
SENSE A
CC
RS+
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
INPUT OFFSET VOLTAGE DISTRIBUTION
(V
- V ) vs. V
OUT REF SENSE
150
125
100
75
12
11
10
9
35
30
25
20
15
10
5
A
V
= 100V/V
A
V
= 100V/V
50
25
8
7
0
6
-25
-50
-75
-100
-125
-150
5
4
3
A = 50V/V
V
2
1
0
0
-50 -25
0
25
50
75 100 125
0
25 50 75 100 125 150 175 200 225 250
(V)
TEMPERATURE (°C)
V
SENSE
V
OS
(µV)
TOTAL ERROR vs. SUPPLY VOLTAGE
(V
= 3mV)
TOTAL ERROR vs. SUPPLY VOLTAGE
TOTAL ERROR vs. TEMPERATURE
SENSE
2.0
1.5
0.5
0.4
1.5
1.0
0.5
0
V
V
= 50mV
SENSE
A
= 100V/V
0.3
V
A
= 75mV
SENSE
1.0
= 50V/V
V
CC
= 24V
V
0.2
0.5
0.1
A
V
= 100V/V
0
0
V
CC
= 12V
-0.1
-0.2
-0.3
-0.4
-0.5
-0.5
-1.0
-1.5
-2.0
-0.5
-1.0
-1.5
V
A
= 50mV
SENSE
= 100V/V
V
A
= 50V/V
14
V
2
6
10
18
22
4
6
8
10 12 14 16 18 20 22 24
SUPPLY VOLTAGE (V)
-50 -25
0
25
50
75 100 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
MAX4069
REFOUT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
1.250
1.245
1.240
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
180
160
140
120
100
80
140
130
120
110
100
90
REFOUT CONNECTED TO ADJ
A
V
= 50V/V
A
V
= 100V/V
MAX4071
MAX4070
V
CC
= 24V
MAX4069
V
CC
= 12V
MAX4072
80
60
70
40
60
-50 -25
0
25
50
75 100 125
-50 -25
0
25
50
75 100 125
2
4
6
8
10 12 14 16 18 20 22 24
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
6
_______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Typical Operating Characteristics (continued)
(V = V
CC
= 12V, V
= 50mV for gain of 100V/V and 75mV for gain of 50V/V, T = +25°C, unless otherwise noted.)
SENSE A
RS+
MAX4069
REFOUT vs. SUPPLY VOLTAGE
MAX4070
REFOUT vs. TEMPERATURE
MAX4071
REFOUT vs. TEMPERATURE
1.525
1.520
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480
1.475
1.235
1.233
1.231
1.229
1.227
1.225
1.223
1.221
1.219
1.217
1.215
2.540
2.525
2.510
2.495
2.480
2.465
2.450
-50 -25
0
25
50
75 100 125
-50 -25
0
25
50
75 100 125
2
4
6
8
10 12 14 16 18 20 22 24
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
MAX4070
REFOUT vs. SUPPLY VOLTAGE
MAX4071
REFOUT vs. SUPPLY VOLTAGE
V
vs. TEMPERATURE
OH
2.500
2.499
2.498
2.497
2.496
2.495
2.494
2.493
2.492
2.491
1.502
1.501
1.500
1.499
1.498
1.497
1.496
1.495
200
180
160
140
120
100
80
V
= V - V
CC
OH
OUT
I = 500µA
L
60
40
I = 10µA
L
20
2.490
2
0
4
6
8
10 12 14 16 18 20 22 24
2
6
10
14
18
22
-50 -25
0
25
50
75 100 125
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SMALL-SIGNAL GAIN
vs. FREQUENCY
V
vs. TEMPERATURE
PSRR AND CMRR vs. FREQUENCY
OL
5
0
250
225
200
175
150
125
100
75
0
-20
-40
-60
A
V
= 50V/V
V
-5
I = 500µA
L
CMRR
-80
-10
-15
-20
A
= 100V/V
-100
PSRR
50
I = 10µA
L
-120
-140
25
0
0.1
1
10
FREQUENCY (kHz)
100
1000
-50 -25
0
25
50
75 100 125
0.01
0.1
1
10
100
TEMPERATURE (°C)
FREQUENCY (Hz)
_______________________________________________________________________________________
7
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Typical Operating Characteristics (continued)
(V = V
= 12V, V
= 50mV for gain of 100V/V and 75mV for gain of 50V/V, T = +25°C, unless otherwise noted.)
SENSE A
CC
RS+
SMALL-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL TRANSIENT RESPONSE
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4069-72 toc19
MAX4069-72 toc20
MAX4069-72 toc21
GAIN = 100
GAIN = 50
GAIN = 50
INPUT
5mV/div
INPUT
5mV/div
INPUT
50mV/div
OUTPUT
2V/div
OUTPUT
200mV/div
OUTPUT
500mV/div
REF
REF
REF
100µs/div
100µs/div
100µs/div
LARGE-SIGNAL TRANSIENT RESPONSE
STARTUP DELAY
EXITING SHUTDOWN
MAX4069-72 toc22
MAX4069-72 toc23
MAX4069-72 toc24
GAIN = 100
V
V
SHDN
5V/div
CC
10V/div
INPUT
20mV/div
V
V
OUT
2V/div
OUT
5V/div
OUTPUT
2V/div
V
V
REFOUT
2V/div
REFOUT
5V/div
REF
100µs/div
20µs/div
100µs/div
8
_______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Pin Description
PIN
NAME
FUNCTION
MAX4070/
MAX4071
MAX4069
MAX4072
Shutdown Input. Drive SHDN low to select shutdown mode. Connect SHDN
1
1
1
SHDN
to V
for normal operation.
CC
2
3
4
5
2
3
2
3
RS-
RS+
N.C.
GND
Negative Connection to the External Sense Resistor
Positive Connection to the External Sense Resistor
No Connection. Not internally connected.
Ground
—
4
—
4
Adjustable Output Voltage Feedback Input. Connect a resistor-divider
between REFOUT, ADJ, and GND (MAX4069 only, see Functional Diagram).
6
7
—
—
—
ADJ
5
REFOUT Reference Output Voltage (MAX4069/MAX4070/MAX4071)
Voltage Output. The difference voltage, V - V , is proportional to
OUT
REF
the voltage difference between RS+ and RS- and indicates the correct
polarity.
8
6
6
OUT
9
7
8
7
8
5
V
Supply Voltage Input. Bypass V
to GND with a 0.1µF capacitor.
CC
CC
Gain-Setting Input. Connect GSEL low to select gain = 50V/V, or connect
GSEL high to select gain = 100V/V.
10
—
GSEL
—
REFIN Reference Input Voltage (MAX4072)
Functional Diagram
2.7V TO 24V
LOAD
FROM BATTERY
CHARGER
V
CC
RS+
MAX4069
OUT
TO ADC
CSA
R
SENSE
RS-
GSEL
GAIN SELECT
SHUTDOWN
OA
SHDN
REFOUT
ADJ
V
REF
1.23V
R1
R2
GND
_______________________________________________________________________________________
9
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Detailed Description
R
SENSE
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.
RS+
RS-
MAX4069–MAX4072
RG1
RG2
OUT
A1
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 maxi-
mum 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 resis-
tors 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 cur-
rent is given from the reference voltage to GND. The
I
OUT
A2
Q1
Q2
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 bidi-
rectional, current-sense amplifier to accurately monitor
the battery’s current regardless of polarity. Figure 2
shows the MAX4069–MAX4072 used as a bidirectional
direction of V
is totally arbitrary.
SENSE
current monitor. In Figure 2, the direction of V
is
SENSE
The input stage of the MAX4069–MAX4072 is shown in
Figure 1. Its unique topology allows for monitoring bidi-
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
rectional currents through the sense resistor (R
). If,
SENSE
for instance, current flows from RS+ to RS-, the
of REF to V
is usually greater than from REF to
ground. This is useful for implementing either smart bat-
tery packs or fuel gauges.
CC
MAX4069–MAX4072 match for the voltage drop over the
external sense resistor (R ) by increasing the cur-
SENSE
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
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 current-
sense limit.
Adjusting V
(MAX4069)
REF
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
is level-shifted towards the reference voltage (V
),
REF
resulting in a voltage at the output pin (OUT) that swings
above the V voltage for positive-sense voltages and
REF
for REFOUT is 4V (that requires V
≥ 5.1V). The rec-
CC
below V
for negative-sense voltages.
REF
ommended range for the external resistors is: R1 + R2
should be > 20kΩ and < 500kΩ.
10 ______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
I
CHARGE
R
SENSE
I
DISCHARGE
5V
A
= 100
V
V
OUT
- V
REF
RS-
RS+
LOAD
CHARGE
CURRENT
2.5V
V
CC
2
CELLS
MAX4070
GSEL
OUT
TO ADC
-25mV
0
25mV
50mV
V
SENSE
SHDN
REFOUT
2.5V
DISCHARGE
CURRENT
-2.5V
GND
Figure 2. Bidirectional Current Monitor
The MAX4069–MAX4072 sense a wide variety of cur-
rents 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.
External Reference (MAX4072)
The MAX4072 contains REFIN pin for external refer-
ence voltage. The allowable voltage range on REFIN is
1V (min) to 4V (max) with V
≥ 5.1V.
CC
Sense Resistor, R
SENSE
Reference Output
Choose R
based on the following criteria:
(MAX4069/MAX4060/MAX4071)
The REFOUT of the MAX4069/MAX4070/MAX4071 can
sink 100µA and source 500µA. Keep the total capaci-
tance on REFOUT under 500pF to maintain stability.
SENSE
Voltage Loss: A high R
value causes the power-
SENSE
source voltage to degrade through IR loss. For minimal
voltage loss, use the lowest R value.
SENSE
Accuracy: A high R
value allows lower currents
SENSE
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:
to be measured more accurately. This is because off-
sets become less significant when the sense voltage is
larger. For best performance, select R
to provide
SENSE
approximately 75mV (gain of 50V/V) or 50mV (gain of
100V/V) of sense voltage for the full-scale current in
each application.
V
OUT
= V x A
SENSE V
where V
is the full-scale sense voltage, 75mV for
SENSE
Efficiency and Power Dissipation: At high-current lev-
gain of 50V/V, or 50mV for gain of 100V/V. A is the
V
els, the I2R losses in R
can be significant. Take
SENSE
gain of the device.
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.
In applications monitoring high current, ensure that
R
is able to dissipate its own I2R® loss. If the
SENSE
resistor’s power dissipation is exceeded, its value may
drift or it may fail altogether, causing a differential volt-
age across the terminals in excess of the absolute max-
imum ratings. Use resistors specified for current-
sensing applications.
Inductance: Keep inductance low if I
has a large
SENSE
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
I2R is a registered trademark of Instruments for Research and
Industry, Inc.
______________________________________________________________________________________ 11
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Table 1. Recommended Component Values
FULL-SCALE
CURRENT
(A)
FULL-SCALE OUTPUT
VOLTAGE WITH RESPECT
TO REF (V)
CURRENT-SENSE
RESISTOR (mΩ)
GAIN
(V/V)
V
SENSE
(mV)
0.075
0.05
0.75
0.5
50
100
50
75
50
75
50
75
50
75
50
75
50
3.75
5.0
1000
100
20
3.75
5.0
100
50
3.75
2.5
3.75
5.0
100
50
7.5
3.75
5.0
10
5.0
100
50
15.0
10.0
3.75
5.0
5
100
core, as in metal-film or wire-wound resistors, they are
a straight band of metal and are available in values
under 1Ω.
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 capaci-
tors are not required for operation or stability and their
use does not degrade performance.
Peak Current: The maximum current through R
must be limited to:
SENSE
I
= 0.3V / (R
+ R
)
PEAK
SENSE
TRACE
where R
is the total stray resistance from RS+
SENSE
TRACE
and RS- to R
. To prevent forwarding the back-to-
back diodes between the differential input, the absolute
maximum of the differential input voltage is 0.3V.
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
Dynamic Range Considerations
Although the MAX4069–MAX4072 have fully symmetri-
cal, bidirectional, V
input capability, the output-
SENSE
voltage range is usually higher from REF to V
and
CC
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 moni-
tored 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 ade-
quate to handle the swings without clipping or running
out of headroom.
V
Using differential measurement between V
OUT
and REF prevents this problem. For highest current-mea-
surement accuracy, use a single-point star ground.
OUT.
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 V
for normal operation.
CC
12 ______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Pin Configurations
TOP VIEW
SHDN
RS-
1
2
3
4
8
7
6
5
GSEL
SHDN
1
2
3
4
5
10 GSEL
RS-
RS+
N.C.
GND
9
8
7
6
V
CC
V
CC
MAX4069
MAX4070
MAX4071
MAX4072
OUT
RS+
OUT
REFOUT
ADJ
GND
REFOUT (REFIN)
µMAX
QFN/µMAX
(REFIN) FOR MAX4072 ONLY
Layout
Chip Information
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.
TRANSISTOR COUNT: 338
PROCESS: BiCMOS
For accurate measurement of V
, the Kelvin
SENSE
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
recommended to keep the value of R
reasonably
SENSE
higher than the values of the trace’s resistance.
______________________________________________________________________________________ 13
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
µ
14 ______________________________________________________________________________________
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
4X S
8
8
MILLIMETERS
INCHES
DIM MIN
MAX
MAX
MIN
-
-
0.043
0.006
0.037
0.014
0.007
0.120
1.10
0.15
0.95
0.36
0.18
3.05
A
0.002
0.030
0.010
0.005
0.116
0.05
0.75
0.25
0.13
2.95
A1
A2
b
E
H
ÿ 0.50±0.1
c
D
e
0.0256 BSC
0.65 BSC
0.6±0.1
E
H
0.116
0.188
0.016
0∞
0.120
2.95
4.78
0.41
0∞
3.05
5.03
0.66
6∞
0.198
0.026
6∞
L
1
1
α
S
0.6±0.1
0.0207 BSC
0.5250 BSC
BOTTOM VIEW
D
TOP VIEW
A1
A2
A
c
α
e
L
b
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0036
J
1
______________________________________________________________________________________ 15
Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 16
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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