MAX6399

19-3655; Rev 1; 3/06 High-Voltage, Overvoltage/Undervoltage, Protection Switch Controller General Description The MAX6399 is a small overvoltage and undervoltage protection circuit. The device can monitor a DC-DC output voltage and quickly disconnect the power source from the DC-DC input load when an overvoltage condition occurs. A power-OK output signals when the DC-DC input voltage falls below an adjustable threshold. This controller architecture provides the ability to size the external n-channel MOSFET to meet specific load current requirements. When the DC-DC monitored output voltage is below the user-adjustable overvoltage threshold, the GATE output of the MAX6399 goes high to enhance the n-channel MOSFET. The MAX6399 offers internal charge-pump circuitry that allows the GATE voltage to be 10V above the input voltage (VGS = 10V) to fully enhance the external n-channel MOSFET, thus minimizing the drainto-source resistance. When the monitored output voltage rises above the user-adjusted overvoltage threshold, the GATE output rapidly pulls low to shut off the MOSFET. The MOSFET remains latched off until either the MAX6399 input power or SHDN input is cycled. The MAX6399 includes a logic-low shutdown input that disables the GATE. An internal overtemperature detector also disables the gate when the MAX6399 temperature reaches the thermal-shutdown threshold. The device operates over a wide supply voltage range (5.75V to 72V) and is offered in a small TDFN package, fully spec...