The LT4356 surge plug protects loads from high voltage transients. It regulates the output during an overvoltage event, such as a load dump in a car, by controlling the gate of an external n-channel MOSFET. The output is limited to a safe value, allowing the load to continue working.
The LT4356 also monitors the voltage drop between the VCC and SNS pins to prevent overcurrent failures. The internal amplifier limits the current induced voltage to 50mV. Under any fault condition, timer startup is inversely proportional to MOSFET stress. If the timer expires, FLT pin pulls down warning of impending power outage. If this persists, the MOSFETs are turned off. After cooling for a while, the GATE pin pulls up to open the MOSFET again.
The auxiliary amplifier may be used as a voltage detection comparator or a linear voltage regulator that drives an external PNP pass transistor. Back-to-back FeTs can be used for reverse input protection of Schottky diodes, reducing voltage drop and power loss. During shutdown, a shutdown pin reduces the static current of the LT4356-1 to less than 7µA.
The LT4356-2 differs from the LT4356-1 by reducing the static current to 60 μA during shutdown and keeping the auxiliary amplifier active, such as undervoltage locking or alway on regulator.
Pin arrangement
Typical application
Block diagram
Features
● Stop high pressure surges
● The output clamp voltage is adjustable
● Overcurrent protection
● Wide working range :4V to 80V
● Reverse input protection to -60V
● Low 7 μA Shutdown current (LT4356-1)
● Level detection comparator auxiliary amplifier or linear regulator controller (LT4356-2)
● Adjustable fault timer
● Control n channel MOSFET
● The closing pin can withstand -60V to 100V
● Fault output indication
● Ensure operation to 125°C
● Available in (4mm x 3mm) 12 stitches DFN,10-pin MSOP or 16-pin SO package.
Applications
● Automotive/avionics lightning protection
● Hot swap/live swap
● High side switch for battery powered system
● Intrinsically safe application
