Maxim Integrated Products has introduced three overvoltage protectors for automotive and other applications with high transient voltages. The MAX6397, MAX6398 and MAX6399 reduce system cost by allowing the use of lower input-voltage dc-dc regulators.
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.
