High-Voltage, Overvoltage/Undervoltage, Protection Switch Controller

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 drain-to- 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-bar 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 specified from -40°C to +125°C.

Applications

* Networking * RAID * Server * Telecom

* High-Voltage Capability (72V) Allows Direct Monitoring, Ensuring Reliable System Operation in Automotive and Industrial Applications

* Wide Supply Voltage Range (5.75V to 72V)

* Specified from -40°C to +125°C

* Adjustable DC-DC Input Undervoltage-Threshold Power-OK Output

* Adjustable DC-DC Output Overvoltage Thresholds

* Integrated Protection Features Improve System Reliability

* Internal Charge Pump Ensures n-Channel MOSFET

is Fully Enhanced During Normal Operation

(VGS = 10V)

* Fast GATE Shutoff During Overvoltage with 20mA

Sink Capability

* Latches Off External n-Channel MOSFET During

High-Voltage Transients

* Overtemperature-Shutdown Protection

* Enables Functional Safety at System Level