Maxim MAX4172EUA, MAX4172ESA Datasheet

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 current­sense amplifier for portable PCs, telephones, and other
systems where battery/DC power-line monitoring is criti­cal. 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 general­purpose current-source applications. The 0V to 32V input
common-mode range is independent of the supply volt­age, which ensures that current-sense feedback remains
viable, even when connected to a battery in deep dis­charge.

To provide a high level of flexibility, the MAX4172 func­tions 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 sin­gle resistor, accommodating a wide range of battery volt­ages 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 amplifi­er. 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

♦ Low-Cost, High-Side Current-Sense Amplifier
♦ ±0.5% Typical Full-Scale Accuracy Over

Temperature

♦ 3V to 32V Supply Operation
♦ 0V to 32V Input Range—Independent of

Supply Voltage

♦ 800kHz Bandwidth [V

200kHz Bandwidth [V

SENSE
SENSE

= 100mV (1C)]
= 6.25mV (C/16)]

♦ Available in Space-Saving µMAX and SO

Packages

______________Ordering Information

PART

MAX4172ESA
MAX4172EUA -40°C to +85°C

*

Contact factory for availability.

TEMP. RANGE PIN-PACKAGE

-40°C to +85°C

8 SO

8 µMAX*

MAX4172

________________________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

__________________Pin Configuration

TOP VIEW

1

RS+

2

RS­N.C.

N.C.

________________________________________________________________

MAX4172

3

4

µMAX/SO

8

V+
PG

7

OUT

6

5

GND

__________Typical Operating Circuit

UNREGULATED

DC SUPPLY

3V TO 32V

LOW-COST
SWITCHING
REGULATOR

FEEDBACK LOOP
V

OUT

LOW-COST BATTERY CHARGER/CURRENT SOURCE

R



SENSE

RS+

V+

MAX4172

= 500mV/A

50mΩ

V

SENSE

GND





RS-

PG

OUT

0V TO 32V

ANALOG OR
LOGIC SUPPLY

100k

POWER GOOD

I
V

R

OUT

1k

Maxim Integrated Products

OUT

SENSE

= 

/ 100Ω

LOAD/

BATTERY

2A

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

Low-Cost, Precision, High-Side
Current-Sense Amplifier

ABSOLUTE MAXIMUM RATINGS

V+, RS+, RS-, PG ...................................................-0.3V to +36V

OUT..............................................................-0.3V to (V+ + 0.3V)

Differential Input Voltage, V

Current into Any Pin..........................................................±50mA

Continuous Power Dissipation (T

SO (derate 5.88mW/°C above +70°C)..........................471mW

µMAX (derate 4.10mW/°C above +70°C) .....................330mW

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

MAX4172

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.

RS+

- V

............................±700mV

RS-

= +70°C)

A

ELECTRICAL CHARACTERISTICS

(V+ = +3V to +32V; RS+, RS- = 0V to 32V; TA= T

= +25°C.)

T

A

Input Voltage Range
Supply Current

Input Offset Voltage mVMAX4172EUA ±0.2 ±1.6

Positive Input Bias Current

Negative Input Bias Current

Voltage

SENSE

Low-Level Current Error

OUT Power-Supply
Rejection Ratio

OUT Common-Mode
Rejection Ratio

OUT

OUT

V

I

RS+

I

RS-

V+

OS

RS-

/ ∆V+

/ ∆V

RS+

to T

MIN

= 0mA

I

OUT

V+ = 12V, V
V

≤ 2.0V

RS+

V

> 2.0V, I

RS+

V

≤ 2.0V, I

RS+

V

> 2.0V

RS+

V

≤ 2.0V

RS+

V

SENSE

V

= 12V (Note 1)

RS+

V

SENSE

V

= 12V

RS+

3V ≤ V+ ≤ 32V, V

2.0V < V

; unless otherwise noted. Typical values are at V+ = +12V, RS+ = 12V,

MAX

RS+

OUT

OUT

= 6.25mV, V+ = 12V,

= 100mV, V+ = 12V,

< 32V

RS+

Operating Temperature Range

MAX4172E_A....................................................-40°C to +85°C

Storage Temperature Range.............................-65°C to +150°C

Lead Temperature (soldering, 10sec).............................+300°C

CONDITIONS

= 12V

= 0mA

= 0mA

RS+

> 2.0V

MAX4172ESA

-325 42.5

-650 85

MAX4172ESA
MAX4172EUA ±15

MAX4172ESA,

TA= -40°C to 0°C

MAX4172EUA,

TA= -40°C to 0°C

MAX4172ESA,

TA= 0°C to +85°C

MAX4172EUA,

TA= 0°C to +85°C

TA= 0°C to +85°C

±0.1 ±0.75

4

0 27 42.5

05085

UNITSMIN TYP MAXSYMBOLPARAMETER

±8.0

±20

±50

±10

±15

V332V+Operating Voltage Range
V032V

mA0.8 1.6I

µA

µA

mV150 175Maximum V

µA

µAOutput Current Error

µA/V0.2∆I

µA/V0.03∆I

2 _______________________________________________________________________________________

Low-Cost, Precision, High-Side

Current-Sense Amplifier

ELECTRICAL CHARACTERISTICS (continued)

(V+ = +3V to +32V; RS+, RS- = 0V to 32V; TA= T

= +25°C.)

T

A

Maximum Output Voltage
(OUT)

Bandwidth

Maximum Output Current

Transconductance

OUT

G

m

V+ Threshold for PG Output
Low (Note 2)

PG Output Low Voltage

OL

Leakage Current into PG
Power-Off Input Leakage

Current (RS+, RS-)

OUT Settling Time to 1%

Note 1: 6.25mV = 1/16 of typical full-scale sense voltage (C/16).
Note 2: Valid operation of the MAX4172 is guaranteed by design when PG is low.

to T

MIN

; unless otherwise noted. Typical values are at V+ = +12V, RS+ = 12V,

MAX

CONDITIONS

I

≤ 1.5mA

OUT

V

= 100mV

SENSE

V

= 6.25mV (Note 1)

SENSE

Gm= I
V

SENSE

/ (V

OUT

RS+

= 100mV, V

- V

RS+

RS-

),

> 2.0V

TA= 0°C to +85°C

TA= -40°C to 0°C
V+ rising
V+ falling 2.67
I

= 1.2mA, V+ = 2.9V, TA= +25°C

SINK

V+ = 2.5V, TA= +25°C

V+ = 0V, V

V

SENSE

V

SENSE

V

SENSE

V

SENSE

= V

RS+

= 32V µA0.1 1

RS-

= 0mV to 100mV, 10% to 90%
= 100mV to 0mV, 90% to 10% ns800OUT Fall Time

= 5mV to 100mV

Rising

Falling

= 150mV MΩ20OUT Output Resistance

800
200

9.8 10 10.2

9.7 10 10.3

2.77

1.3
6

MAX4172

UNITSMIN TYP MAXSYMBOLPARAMETER

VV+ - 1.2

kHz

mA1.5 1.75I

mA/V

V

V0.4V

µA1

ns400OUT Rise Time

µs

__________________________________________Typical Operating Characteristics

(V+ = +12V, V

1000

950
900
850
800
750
700

650

SUPPLY CURRENT (µA)

600
550
500

010

= 12V, R

RS+

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

TA = +85°C

20

V+ (V)

= 1kΩ, TA= +25°C, unless otherwise noted.)

OUT

vs. SUPPLY VOLTAGE

0.5

0.4

MAX4172-01

0.3

TA = +25°C

TA = -40°C

I

OUT

30

= 0mA

40

0.2

0.1
0

ERROR (%)

-0.1

-0.2

-0.3

-0.4

-0.5
010

TA = +25°C

OUTPUT ERROR

V

SENSE

TA = +85°C

TA = -40°C

20 30

V+ (V)

= 100mV

40

MAX4172-03

1.5

1.0

0.5
0

-0.5

-1.0

ERROR (%)

-1.5

-2.0

-2.5

-3.0
010

C/16 LOAD OUTPUT ERROR

vs. SUPPLY VOLTAGE

20

V+ (V)

_______________________________________________________________________________________ 3

V

SENSE

TA = -40°C

TA = +25°C

TA = +85°C

= 6.25mV

30

MAX4172-02

40