19-1184; Rev 0; 12/96
Low-Cost, Precision, High-Side
Current-Sense Amplifier
_______________General Description
The MAX4172 is a low-cost, precision, high-side current-
sense amplifier for portable PCs, telephones, and other
systems where battery/DC power-line monitoring is criti-
cal. High-side power-line monitoring is especially useful in
battery-powered systems, since it does not interfere with
the battery charger’s ground path. Wide bandwidth
and ground-sensing capability make the MAX4172
suitable for closed-loop battery-charger and general-
purpose current-source applications. The 0V to 32V input
common-mode range is independent of the supply volt-
age, which ensures that current-sense feedback remains
viable, even when connected to a battery in deep dis-
charge.
To provide a high level of flexibility, the MAX4172 func-
tions with an external sense resistor to set the range of
load current to be monitored. It has a current output that
can be converted to a ground-referred voltage with a sin-
gle resistor, accommodating a wide range of battery volt-
ages and currents.
An open-collector power-good output (PG) indicates
when the supply voltage reaches an adequate level to
guarantee proper operation of the current-sense amplifi-
er. The MAX4172 operates with a 3.0V to 32V supply
voltage, and is available in a space-saving, 8-pin µMAX
or SO package.
____________________________Features
o
Low-Cost, High-Side Current-Sense Amplifier
o
±0.5% Typical Full-Scale Accuracy Over
Temperature
o
3V to 32V Supply Operation
o
0V to 32V Input Range—Independent of
Supply Voltage
o
800kHz Bandwidth [V
SENSE
= 100mV (1C)]
200kHz Bandwidth [V
SENSE
= 6.25mV (C/16)]
o
Available in Space-Saving µMAX and SO
Packages
MAX4172
______________Ordering Information
PART
MAX4172ESA
MAX4172EUA
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 SO
8 µMAX*
*Contact
factory for availability.
________________________Applications
Portable PCs: Notebooks/Subnotebooks/Palmtops
Battery-Powered/Portable Equipment
Closed-Loop Battery Chargers/Current Sources
Smart-Battery Packs
Portable/Cellular Phones
Portable Test/Measurement Systems
Energy Management Systems
__________Typical Operating Circuit
UNREGULATED
DC SUPPLY
3V TO 32V
R
SENSE
50mΩ
V
SENSE
LOW-COST
SWITCHING
REGULATOR
0V TO 32V
ANALOG OR
LOGIC SUPPLY
100k
2A
RS+
V+
RS-
PG
__________________Pin Configuration
MAX4172
POWER GOOD
LOAD/
BATTERY
TOP VIEW
RS+ 1
RS- 2
N.C. 3
N.C. 4
8
7
V+
PG
OUT
GND
GND
FEEDBACK LOOP
V
OUT
= 500mV/A
OUT
I
OUT
=
V
SENSE
/ 100Ω
MAX4172
6
5
R
OUT
1k
µMAX/SO
LOW-COST BATTERY CHARGER/CURRENT SOURCE
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
