Rainbow Electronics MAX9938 User Manual

General Description

The MAX9938 high-side current-sense amplifier offers
precision accuracy specifications of VOSless than
500μV (max) and gain error less than 0.5% (max).
Quiescent supply current is an ultra-low 1μA. The
MAX9938 fits in a tiny, 1mm x 1mm UCSP™ package
size or a 5-pin SOT23 package, making the part ideal for
applications in notebook computers, cell phones, PDAs,
and all battery-operated portable devices where accura­cy, low quiescent current, and small size are critical.

The MAX9938 features an input common-mode voltage
range from 1.6V to 28V. These current-sense amplifiers
have a voltage output and are offered in three gain ver­sions: 25V/V (MAX9938T), 50V/V (MAX9938F), and
100V/V (MAX9938H).

The three gain selections offer flexibility in the choice of
the external current-sense resistor. The very low 500μV
(max) input offset voltage allows small 25mV to 50mV
full-scale V

SENSE

voltage for very low voltage drop at

full-current measurement.

The MAX9938 is offered in tiny 4-bump, UCSP (1mm x
1mm x 0.6mm footprint) and 5-pin SOT23 packages,
specified for operation over the -40°C to +85°C extend­ed temperature range.

Applications

Cell Phones

PDAs

Power Management Systems

Portable/Battery-Powered Systems

Notebook Computers

Features

♦ Ultra-Low Supply Current of 1µA (max)

♦ Low 500µV (max) Input Offset Voltage

♦ Low < 0.5% (max) Gain Error

♦ Input Common Mode: +1.6V to +28V

♦ Voltage Output

♦ Three Gain Versions Available

25V/V (MAX9938T)
50V/V (MAX9938F)
100V/V (MAX9938H)

♦ Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP

or 5-Pin SOT23 Package

MAX9938

1µA, 4-Bump UCSP/SOT23,

Precision Current-Sense Amplifier

________________________________________________________________

Maxim Integrated Products

1

Pin Configurations

19-4110; Rev 0; 4/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

UCSP is a trademark of Maxim Integrated Products, Inc.

Ordering Information

+

Denotes a lead-free package.

Note: All devices are specified over the -40°C to +85°C
extended temperature range.

PART

PIN­PACKAGE

TOP MARK

MAX9938TEBS+

4 UCSP 25 +AGD

MAX9938FEBS+

4 UCSP 50 +AGE

MAX9938HEBS+

4 UCSP 100 +AGF

MAX9938TEUK+

5 SOT23 25 +AFFB

MAX9938FEUK+

5 SOT23 50 +AFFC

MAX9938HEUK+

5 SOT23 100 +AFFD

GAIN (V/V)

(BUMPS ON BOTTOM)

A1

RS+

MAX9938T/F/H

B1 B2

GND

TOP VIEW

UCSP

RS-A2

OUT

RS+ RS-

54

MAX9938T/F/H

132

GND OUTGND

SOT23

MAX9938

1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

RS+

= V

RS-

= 3.6V, V

SENSE

= (V

RS+

- V

RS-

) = 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

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.

Note 1: All devices are 100% production tested at TA= +25°C. All temperature limits are guaranteed by design.
Note 2: V

OUT

= 0. ICCis the total current into RS+ plus RS- pins.

Note 3: V

OS

is extrapolated from measurements for the gain-error test.

Note 4: Gain error is calculated by applying two values of V

SENSE

and calculating the error of the slope vs. the ideal:

Gain = 25, V

SENSE

is 20mV and 120mV.

Gain = 50, V

SENSE

is 10mV and 60mV.

Gain = 100, V

SENSE

is 5mV and 30mV.

Note 5: The device is stable for any external capacitance value.
Note 6: V

OH

is the voltage from V

RS-

to V

OUT

with V

SENSE

= 3.6V/gain.

RS+, RS- to GND....................................................-0.3V to +30V

OUT to GND .............................................................-0.3V to +6V

RS+ to RS- ...........................................................................±30V

Short-Circuit Duration: OUT to GND ..........................Continuous

Continuous Input Current (Any Pin)..................................±20mA

Continuous Power Dissipation (T

A

= +70°C)

4-Bump UCSP (derate 3.0mW/°C above +70°C).........238mW

5-Pin SOT23 (derate 3.9mW/°C above +70°C)............312mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

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

Bump Temperature (soldering) Reflow............................+235°C

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Current (Note 2) I

Common-Mode Input Range V

Common-Mode Rejection Ratio CMRR 1.6V < V

Input Offset Voltage (Note 3) V

Gain G

Gain Error (Note 4) GE

Output Resistance R

OUT High Voltage V

Small-Signal Bandwidth
(Note 5)

Output Settling Time t

Power-Up Time t

V

= 5V, TA = +25°C 0.5 0.85

RS+

V

= 5V, -40°C < TA < +85°C 1.1

CC

CM

OS

RS+

V

= 28V, TA = +25°C 1.1 1.8

RS+

V

= 28V, -40°C < TA < +85°C 2.5

RS+

Guaranteed by CMRR , -40°C < TA < +85°C 1.6 28 V

RS+

TA = +25°C ±100 ±500

-40°C < TA < +85°C ±600

MAX9938T 25

MAX9938F 50

MAX9938H 100

TA = +25°C ±0.1 ±0.5

OUT

-40°C < T

(Note 5) 7.0 10 13.2 kΩ

A

Gain = 25 1.5 15

Gain = 50 3 30OUT Low Voltage V

OL

Gain = 100 6 60

V

OH

BW

S

ON

= V

OH

RS-

V

V

V

= 50mV, gain = 25 125

SENSE

= 50mV, gain = 50 60

SENSE

= 50mV, gain = 100 30

SENSE

1% final value, V

1% final value, V

< 28V, -40°C < TA < +85°C 94 130 dB

< +85°C ±0.6

- V

(Note 6) 0.1 0.2 V

OUT

= 50mV 100 μs

SENSE

= 50mV 200 μs

SENSE

μA

μV

V/V

%

mV

kHz

MAX9938

1µA, 4-Bump UCSP/SOT23,

Precision Current-Sense Amplifier

_______________________________________________________________________________________ 3

Typical Operating Characteristics

(V

RS+

= V

RS-

= 3.6V, TA= +25°C, unless otherwise noted.)

N (%)

INPUT OFFSET (μV)

30

25

20

15

10

-30

-35

-40

-45

-50

INPUT OFFSET VOLTAGE HISTOGRAM

5

0

-0.4 -0.3 -0.2 -0.1 0 0.2 0.30.1 0.4
INPUT OFFSET VOLTAGE (mV)

INPUT OFFSET

vs. COMMON-MODE VOLTAGE

MAX9938 toc01

MAX9938 toc04

GAIN ERROR HISTOGRAM

30

25

20

15

N (%)

10

5

0

-0.4 -0.3 -0.2 -0.1 0 0.2 0.30.1 0.4
GAIN ERROR (%)

INPUT OFFSET

vs. TEMPERATURE

60

50

40

30

INPUT OFFSET (μV)

20

10

MAX9938 toc02

MAX9938 toc05

SUPPLY CURRENT

vs. TEMPERATURE

1.4

1.2

1.0

0.8

0.6

SUPPLY CURRENT (μA)

0.4

0.2

0

-40 85

10-15 35 60

TEMPERATURE (°C)

28V

3.6V

1.8V

SUPPLY CURRENT

vs. COMMON-MODE VOLTAGE

1.4

1.2

1.0

0.8

0.6

SUPPLY CURRENT (μA)

0.4

0.2

MAX9938 toc03

MAX9938 toc06

-55
030

SUPPLY VOLTAGE (V)

252010515

0

GAIN ERROR

vs. COMMON-MODE VOLTAGE

MAX9938 toc07

0.08

0.07

0.06

0.05

0.04

0.03

GAIN ERROR (%)

0.02

0.01

0

-40

0.1

0

-0.1

-0.2

GAIN ERROR (%)

-0.3

-0.4

-0.5
010155 202530

VOLTAGE (V)

10-15 35 60-40 85

TEMPERATURE (°C)

GAIN ERROR

vs. TEMPERATURE

10 60 8535-15

TEMPERATURE (°C)

MAX9938 toc08

0

0

15 2010 30525

SUPPLY VOLTAGE (V)

V

vs. V

OUT

SENSE

(SUPPLY = 3.6V)

4.0

3.5

3.0

2.5

(V)

2.0

OUT

V

1.5

1.0

0.5

0

0 150

G = 50

V

SENSE

G = 100

10050

(mV)

MAX9938 toc09

G = 25