Features

• Stops High Voltage Surges
• Adjustable Output Clamp Voltage
• Overcurrent Protection
• Wide Operation Range: 4V to 80V
• Reverse Input Protection to –60V
• Low 7μA Shutdown Current, LT4356-1
• Adjustable Fault Timer
• Controls N-channel MOSFET
• Shutdown Pin Withstands –60V to 100V
• Fault Output Indication
• Guaranteed Operation –55°C to 125°C
• Auxiliary Amplifier for Level Detection Comparator or Linear Regulator Controller
• Available in 10-Pin MSOP or 16-Pin SO Packages

Typical Application

Description

The LT4356 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET. The output is limited to a safe value thereby allowing the loads to continue functioning. The LT4356MP also monitors the voltage drop between the V_CC and SNS pins to protect against overcurrent faults. An internal amplifier limits the current sense voltage to 50mV. In either fault condition, a timer is started inversely proportional to MOSFET stress. If the timer expires, the FLT pin pulls low to warn of an impending power-down. If the condition persists, the MOSFET is turned off. After a cooldown period, the GATE pin pulls up turning on the MOSFET again.

The auxiliary amplifier may be used as a voltage detection comparator or as a linear regulator controller driving an external PNP pass transistor.

Back-to-back FETs can be used in lieu of a Schottky diode for reverse input protection, reducing voltage drop and power loss. A shutdown pin reduces the quiescent current to less than 7μA for the LT4356-1 during shutdown. The LT4356-2 differs from the LT4356-1 during shutdown by reducing the quiescent current to 60μA and keeping alive the auxiliary amplifier for uses such as an undervoltage lockout or always-on regulator.