_______________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.

________________________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

____________________________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 Available in Space-Saving µMAX and SO

Packages

Low-Cost, Precision, High-Side

Current-Sense Amplifier

________________________________________________________________

Maxim Integrated Products

1

OUT

GND

FEEDBACK LOOP

LOW-COST BATTERY CHARGER/CURRENT SOURCE

1k

100k

ANALOG OR

LOGIC SUPPLY

2A

0V TO 32V

V+

RS+

50m

Ω

RS-

PG

MAX4172

POWER GOOD

LOAD/

BATTERY

LOW-COST

SWITCHING

REGULATOR

UNREGULATED

DC SUPPLY

3V TO 32V

__________________Pin Configuration

TOP VIEW

OUT

GND

N.C.

1

2

8

7

V+

PG

RS-

N.C.

RS+

µMAX/SO

3

4

6

5

MAX4172

__________Typical Operating Circuit

19-1184; Rev 0; 12/96

PART

MAX4172ESA

MAX4172EUA

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

8 SO

8 µMAX*

______________Ordering Information

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

*

Contact factory for availability.