MAX4840

Features:

·Overvoltage Protection Up to 28V
·Preset 7.4V or 5.8V Overvoltage Trip Level
·Drive Low-Cost NMOS FET
·Internal 50ms Startup Delay
·Internal Charge Pump
·Undervoltage Lockout
·15kV ESD-Protected Input
·Voltage Fault FLAG Indicator
·6-Pin SC70 Package


Application

·Cell Phones
·Digital Still Cameras
·PDAs and Palmtop Devices
·MP3 Players


Pinout




Specifications

IN to GND ......................................................................-0.3V to +30V
GATE to GND .................................................................-0.3V to +12V
EN, FLAG to GND .............................................................-0.3V to +6V
Continuous Power Dissipation (TA = +70°C)
6-Pin SC70 (derate 3.1mW/°C above +70°C) ......................245mW
Operating Temperature Range ....................................-40 to +85
Junction Temperature ............................................................. +150
Storage Temperature Range ......................................-65 to +150
Lead Temperature (soldering, 10s) ..........................................+300


Description

The MAX4840 is overvoltage protection ICs that protect low-voltage systems against voltages of up to 28V. If the input voltage exceeds the overvoltage trip level, the MAX4840 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 MAX4838/MAX4839 have a 7.4V overvoltage threshold, and the MAX4840/MAX4841 have a 5.8V overvoltage threshold. All devices have an undervoltage lockout threshold of 3.25V. In addition to the single FET configuration, the devices can be configured with back-to-back external FETs to prevent currents from being back-driven 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 MAX4838/MAX4840 have an open-drain FLAG output, and the MAX4839/MAX4841 have a push-pull FLAG output. The FLAG output asserts immediately to an overvoltage fault.

Additional features include a 15kV ESD-protected input (when bypassed with a 1µF capacitor) and a shutdown pin (EN) to turn off the device (MAX4838/MAX4840).

All devices are offered in a small 6-pin SC70 package and are specified for operation from -40°C to +85°C.