MAX471 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – Precision, High-Side Current-Sense Amplifiers

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.
________________________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
____________________________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
______________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
_________________Pin Configurations
RS+
RS-
RS+
RS-
100k
3V
TO
MAX471
SIGN
36V
SHDN GND
OUT
I_LOAD
2000
2k
I_LOAD TO
LOAD or CHARGER
LOGIC
SUPPLY
DISCHARGE/CHARGE
V_OUT (1V/A)
TOP VIEW
SHDN 1
RS+ 2
RS+ 3
GND 4
MAX471
DIP/SO
8 OUT
7 RS-
6 RS-
5 SIGN
MAX472 Pin Configuration continued on last page.
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