General Description

The MAX4838A/MAX4840A/MAX4842A are overvoltage-

protection ICs that protect low-voltage systems against

voltages of up to +28V. If the input voltage exceeds the

overvoltage trip level, the MAX4838A/MAX4840A/

MAX4842A turn off the low-cost external n-channel

FET(s) to prevent damage to the protected components.

An internal charge pump eliminates the need for external

capacitors and drives the FET gate for a simple,

robust solution.

The MAX4838A has a 7.4V overvoltage threshold, and

the MAX4840A has a 5.8V overvoltage threshold. The

MAX4842A has a 4.7V overvoltage threshold. The

MAX4838A/MAX4840A have an undervoltage-lockout

(UVLO) threshold of 3.25V, while the MAX4842A has a

UVLO of 2.5V. In addition to the single FET configura-

tion, the devices can be configured with back-to-back

external FETs to prevent currents from being back-dri-

ven into the adapter.

On power-up, the device waits for 50ms before driving

GATE high. FLAG is held low for an additional 50ms

after GATE goes high before deasserting. The

MAX4838A/MAX4840A/MAX4842A have an open-drain

FLAG output. The FLAG output asserts immediately to

an overvoltage fault.

Additional features include a ±15kV (HBM) ESD-pro-

tected input (when bypassed with a 1µF capacitor) and

a shutdown pin (EN) to turn off the device.

All devices are offered in a small 6-pin SC70 and 6-pin

1.5mm x 1.0mm µDFN packages and are specified

over the -40°C to +85°C extended temperature range.

Applications

Cell Phones

Digital Still Cameras

PDAs and Palmtop Devices

MP3 Players

Features

♦ Overvoltage Protection Up to +28V

♦ Preset 7.4V, 5.8V, or 4.7V Overvoltage Trip Level

♦ Drives Low-Cost nMOS FET

♦ Internal 50ms Startup Delay

♦ Internal Charge Pump

♦ Undervoltage Lockout

♦ ±15kV ESD-Protected Input

♦ Voltage Fault FLAG Indicator

♦ 6-Pin SC70 and µDFN Packages

♦ Lead Free

Overvoltage-Protection Controllers with

Status

FLAG

________________________________________________________________ Maxim Integrated Products

1

MAX4838A

MAX4840A

MAX4842A

INPUT

+1.2V TO +28V

IN

EN

GATE

FLAG

GND

1

6

4

2

3

OUTPUT

1

µF

NOTE: EN AND PULLUP

RESISTOR

NMOS

Typical Operating Circuit

Ordering Information

19-3979; Rev 0; 2/06

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Pin Configuration appears at end of data sheet.

PART

PIN-

PACKAGE

TOP

MARK

PKG

CODE

MAX4838AEXT+T

6 SC70

ACY

X6S-1

MAX4838AELT+

6 µDFN

KU

L611-1

MAX4840AEXT+T

6 SC70

ACZ

X6S-1

MAX4840AELT+

6 µDFN

KV

L611-1

MAX4842AEXT+T

6 SC70

ADA

X6S-1

MAX4842AELT+*

6 µDFN

KW

L611-1

Selector Guide

PART

UVLO

THRESHOLD

(V)

OV

TRIP

LEVEL

(V)

EN

INPUT

FLAG

OUTPUT

MAX4838A

3.25

7.4

Yes

Open-Drain

MAX4840A

3.25

5.8

Yes

Open-Drain

MAX4842A

2.50

4.7

Yes

Open-Drain

Note: All devices specified for the -40°C to +85°C extended

temperature range.

*Future product—contact factory for availability.

+Denotes lead-free package.