The devices operate from 5.75 V to 72 V and can be configured either as a switch controller that turns off an external n-channel switch during an overvoltage condition, or as a voltage limiter that regulates the output to allow continuous operation.

An adjustable threshold allows two external resistors to set the overvoltage threshold level. An internal charge pump ensures that the n-channel switch is fully enhanced during normal operating mode. In the switch-controller mode, the n-channel MOSFET is quickly shut off as the MOSFET's gate is quickly pulled down through an internal current source. In the voltage-limiting mode, the MOSFET is turned on and off to maintain a regulated voltage at the output.

The MAX6397 has an independent “always-on” linear regulator that can deliver up to 100 mA output current with four fixed-output options of 5 V, 3.3 V, 2.5 V, and 1.8 V. It also features a power-good indicator.

The MAX6399 offers an undervoltage and overvoltage threshold with a power-good indicator. An overvoltage latch mode keeps the n-channel MOSFET off until the power is recycled or the shutdown input is toggled. A shutdown input is available for manually shutting off the n-channel switch and thermal shutdown protection.

All three devices are offered in a small, 3 mm x 3 mm TDFN package and are fully specified from the -40 degrees celsius to +125 degrees celsius automotive temperature range.