Not Recommended for New Designs
This product was manufactured for Maxim by an outside wafer foundry
using a process that is no longer available. It is not recommended for
new designs. The data sheet remains available for existing users.
A Maxim replacement or an industry second-source may be available.
Please see the QuickView data sheet for this part or contact technical
support for assistance.
For further information,
contact Maxim’s Applications Tech Support.
19-0335; Rev 2; 12/96
Precision, High-Side
Current-Sense Amplifiers
_______________General Description
The MAX471/MAX472 are complete, bidirectional, high-
side current-sense amplifiers for portable PCs, tele-
phones, and other systems where battery/DC
power-line monitoring is critical. High-side power-line
monitoring is especially useful in battery-powered sys-
tems, since it does not interfere with the ground paths
of the battery chargers or monitors often found in
“smart” batteries.
The MAX471 has an internal 35mΩ current-sense resis-
tor and measures battery currents up to ±3A. For appli-
cations requiring higher current or increased flexibility,
the MAX472 functions with external sense and gain-set-
ting resistors. Both devices have a current output that
can be converted to a ground-referred voltage with a
single resistor, allowing a wide range of battery volt-
ages and currents.
An open-collector SIGN output indicates current-flow
direction, so the user can monitor whether a battery is
being charged or discharged. Both devices operate
from 3V to 36V, draw less than 100µA over tempera-
ture, and include a 18µA max shutdown mode.
____________________________Features
o
Complete High-Side Current Sensing
o
Precision Internal Sense Resistor (MAX471)
o
2% Accuracy Over Temperature
o
Monitors Both Charge and Discharge
o
3A Sense Capability with Internal Sense Resistor
(MAX471)
o
Higher Current-Sense Capability with External
Sense Resistor (MAX472)
o
100µA Max Supply Current
o
18µA Max Shutdown Mode
o
3V to 36V Supply Operation
o
8-Pin DIP/SO Packages
MAX471/MAX472
______________Ordering Information
PART
MAX471CPA
MAX471CSA
MAX471EPA
MAX471ESA
MAX472CPA
MAX472CSA
MAX472EPA
MAX472ESA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
________________________Applications
Portable PCs:
Notebooks/Subnotebooks/Palmtops
Smart Battery Packs
Cellular Phones
Portable Phones
Portable Test/Measurement Systems
Battery-Operated Systems
Energy Management Systems
__________Typical Operating Circuit
RS+
RS+
RS-
RS-
I
LOAD
TO
LOAD or CHARGER
LOGIC
SUPPLY
100k
3V
TO
36V
SHDN
_________________Pin Configurations
TOP VIEW
SHDN
1
8
7
OUT
RS-
RS-
SIGN
MAX471
GND
RS+ 2
DISCHARGE/CHARGE
V
OUT
(1V/A)
RS+ 3
GND 4
SIGN
OUT
I
LOAD
2000
2k
MAX471
6
5
DIP/SO
MAX472 Pin Configuration continued on last page.
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Precision, High-Side
Current-Sense Amplifiers
MAX471/MAX472
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, RS+, RS-, V
CC
to GND....................-0.3V, +40V
RMS Current, RS+ to RS- (MAX471 only)..........................±3.3A
Peak Current, (RS+ to RS-) ......................................see Figure 5
Differential Input Voltage, RG1 to RG2 (MAX472 only) .....±0.3V
Voltage at Any Pin Except SIGN
MAX471 only ...........................................-0.3V to (RS+ - 0.3V)
MAX472 only ..........................................-0.3V to (V
CC
+ 0.3V)
Voltage at SIGN......................................................-0.3V to +40V
Current into SHDN, GND, OUT, RG1, RG2, V
CC
................±50mA
Current into SIGN.................................................+10mA, -50mA
Continuous Power Dissipation (T
A
= +70°C)
MAX471 (Note 1):
Plastic DIP (derate 17.5mW/°C above +70°C) ..................1.4W
SO (derate 9.9mW/°C above +70°C) .............................791mW
MAX472 :
Plastic DIP (derate 9.09mW/°C above +70°C) ..............727mW
SO (derate 5.88mW/°C above +70°C) ...........................471mW
Operating Temperature Ranges
MAX47_C_A ........................................................0°C to +70°C
MAX47_E_A .....................................................-40°C to +85°C
Junction Temperature Range ............................-60°C to +150°C
Storage Temperature Range .............................-60°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Note 1:
Due to special packaging considerations, MAX471 (DIP, SO) has a higher power dissipation rating than the MAX472. RS+
and RS- must be soldered to large copper traces to achieve this dissipation rating.
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—MAX471
(RS+ = +3V to +36V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Supply Voltage
Supply Current
Sense Current
Sense Resistor
Current-Sense Ratio
No-Load OUT Error
Low-Level OUT Error
Power-Supply Rejection Ratio
SIGN Threshold (I
LOAD
required
to switch SIGN)
SIGN Output Leakage Current
SIGN Sink Current
Shutdown Supply Current
SHDN Input Low Voltage
SHDN Input Low Current
SHDN Input High Voltage
SHDN Input High Current
OUT Output Voltage Range
OUT Output Resistance
OUT Rise, Fall Time
OUT Settling Time to 1%
of Final Value
2
I
OL
V
IL
I
IL
V
IH
I
IH
V
OUT
R
OUT
t
R
, t
F
t
s
I
LOAD
= 3.0A, V
OUT
= 0V to (V
RS+
- 1.5V)
I
LOAD
= 50mA to 3.0A, R
OUT
= 2kΩ,
C
OUT
= 50pF, 10% to 90%
I
LOAD
= 100mA to 3.0A, R
OUT
= 2kΩ,
C
OUT
= 50pF
V
SHDN
= 2.4V
0
1
3
4
15
V
SHDN
= 0V
2.4
1.0
V
RS+
- 1.5
PSRR
SYMBOL
V
RS+
I
RS+
I
LOAD
R
SENSE
I
OUT
/
I
LOAD
I
LOAD
= 1A,
RS+ = 10V
I
LOAD
= 0A,
RS+ = 10V
I
LOAD
= 30mA,
RS+ = 10V
MAX471C
MAX471E
V
SIGN =
36V
V
SIGN
= 0.3V
0.1
1.5
18.0
0.3
1.0
I
RS+(SHDN)
V
SHDN
= 2.4V; V
CC
= 3V to 20V
MAX471C
MAX471E
MAX471C
MAX471E
MAX471C
MAX471E
3V
≤
RS+
≤
36V, I
LOAD
= 1A
0.490
0.4875
35
0.500
0.500
I
LOAD
= 0A, excludes I
SIGN
CONDITIONS
MIN
3
50
TYP
MAX
36
113
±3
70
0.510
0.5125
2.5
3.0
±2.5
±3.0
0.1
±6.0
±7.0
1.0
UNITS
V
µA
A
RMS
mΩ
mA/A
µA
µA
%/V
mA
µA
mA
µA
V
µA
V
µA
V
MΩ
µs
µs
±4.0
_______________________________________________________________________________________
Precision, High-Side
Current-Sense Amplifiers
ELECTRICAL CHARACTERISTICS—MAX472
(V
CC
= +3V to +36V, RG1 = RG2 = 200Ω, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Supply Voltage
Supply Current
Input Offset Voltage
(Note 2)
Input Bias Current
Input Bias-Current Matching
OUT Current Accuracy
No-Load OUT Error
Low-Level OUT Error
Power-Supply Rejection Ratio
SIGN Threshold (V
SENSE
required to switch SIGN)
SIGN Output Leakage Current
SIGN Output Sink Current
Shutdown Supply Current
SHDN Input Low Voltage
SHDN Input Low Current
SHDN Input High Voltage
SHDN Input High Current
OUT Output Voltage Range
OUT Output Resistance
OUT Rise, Fall Time
OUT Settling Time to 1%
of Final Value
Maximum Output Current
I
CC(SHDN)
V
IL
I
IL
V
IH
I
IH
V
OUT
R
OUT
t
R
, t
F
t
s
I
OUT
I
OUT
= 1.5mA
V
SENSE
= 5mV to 150mV, R
OUT
= 2kΩ,
C
OUT
= 50pF, 10% to 90%
V
SENSE
= 5mV to 150mV, R
OUT
= 2kΩ,
C
OUT
= 50pF
1.5
V
SHDN
= 2.4V
0
1
3
4
15
V
SHDN
= 0V
2.4
1.0
V
CC
- 1.5
PSRR
SYMBOL
V
CC
I
CC
V
OS
I
RG1
, I
RG2
I
OS
I
RG
/I
OUT
I
RG1
- I
GR2
V
SENSE
= 100mV,
V
CC
= 10V (Note 3)
V
CC
= 10V,
V
SENSE
= 0V
V
CC
= 10V,
V
SENSE
= 3mV
MAX472C
MAX472E
MAX472C
MAX472E
MAX472C
MAX472E
MAX472C
MAX472E
0.1
1.5
18.0
0.3
1.0
60
60
I
LOAD
= 0A, excludes I
SIGN
; V
CC
= 3V to 20V
MAX472C
MAX472E
20
±0.4
CONDITIONS
MIN
3
20
TYP
MAX
36
48
120
140
35
±3.0
±2
±2.5
2.5
3
±2.5
±3.0
0.1
120
140
1.0
UNITS
V
µA
µV
µA
µA
%
µA
µA
%/V
µV
µA
mA
µA
V
µA
V
µA
V
MΩ
µs
µs
mA
MAX471/MAX472
3V
≤
V
CC
≤
36V, V
SENSE
= 100mV
V
CC
= 10V
V
SIGN
= 36V
V
SIGN
= 0.3V
V
SHDN
= 2.4V; V
CC
= 3V to 20V
Note 2:
V
OS
is defined as the input voltage (V
SENSE
) required to give minimum I
OUT
.
Note 3:
V
SENSE
is the voltage across the sense resistor.
_______________________________________________________________________________________
3
Precision, High-Side
Current-Sense Amplifiers
MAX471/MAX472
__________________________________________Typical Operating Characteristics
(Typical Operating Circuit (MAX471) or circuit of Figure 4, RG1 = RG2 = 200Ω, R
OUT
= 2kΩ (MAX472), T
A
= +25°C, unless
otherwise noted.)
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
MAX1471-01
SHUTDOWN CURRENT vs.
SUPPLY VOLTAGE
MAX1471-02
SIGN THRESHOLD vs.
SUPPLY VOLTAGE
T
A
= -40°C
3
SIGN THRESHOLD (mA)
2
1
T
A
= +25°C
0
-1
-2
T
A
= +85°C
MAX1471-03
65
60
SUPPLY CURRENT (µA)
55
T
A
= +85°C
2.5
T
A
= -40°C
4
2.0
I
SHDN
(µA)
50
45
T
A
= +25°C
1.5
T
A
= +25°C
1.0
T
A
= +85°C
T
A
= -40°C
40
35
3
6
9 12 15 18 21 24 27 30 33 36
V
RS+
(V)
0.5
0
3
6
9 12 15 18 21 24 27 30 33 36
V
RS+
(V)
3
6
9 12 15 18 21 24 27 30 33 36
V
RS+
(V)
MAX471
NO-LOAD OFFSET CURRENT vs.
SUPPLY VOLTAGE
MAX1471-04
MAX471
ERROR vs. LOAD CURRENT
MAX471-05
MAX471
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
I
LOAD
= 1A
35
RS+ RS–
MAX471-06
2.4
VS+ = VS-
2.2
T
A
= -40°C
OFFSET CURRENT (µA)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
3
6
T
A
= +25°C
T
A
= +85°C
15
12
9
6
ERROR (%)
I
LOAD
FROM RS- TO RS+
40
V = 0V TO 0.5V
A
30
PSRR (%)
25
20
15
5V
OUT
GND
1µF
3
0
-3
-6
-9
-12
-15
I
LOAD
FROM RS+ TO RS-
V
5Ω
V = 0V TO 1V
V = 0mV TO 50mV
10
5
0
0.01
0.10
I
LOAD
(A)
1
10
0.01
0.10
1
10
100
1000
POWER-SUPPLY FREQUENCY (kHz)
9 12 15 18 21 24 27 30 33 36
V
RS+
(V)
MAX471
RS+ TO RS- RESISTANCE vs.
TEMPERATURE
MAX1471-07
MAX472
NO-LOAD OUTPUT ERROR vs.
SUPPLY VOLTAGE
MAX1471-08
MAX472
ERROR vs. SUPPLY VOLTAGE
V
RG1
-V
RG2
= 60mV,
RG1 = RG2 = 200Ω
1.00
ERROR (%)
T
A
= +85°C
0.90
T
A
= +25°C
MAX1471-09
40
38
RESISTANCE (mΩ)
36
3.0
2.5
2.0
I
OUT
(µA)
1.5
T
A
= +25°C
1.0
0.5
T
A
= -40°C
RG1 = RG2 = 0Ω
T
A
= +85°C
1.10
34
32
30
28
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0.80
T
A
= -40°C
0
3
6
9 12 15 18 21 24 27 30 33 36
V
CC
(V)
0.70
3
6
9 12 15 18 21 24 27 30 33 36
V
CC
(V)
4
_______________________________________________________________________________________
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