Surge stopper integrates ideal diode for comprehensive protection against transient voltages

July 24, 2012 //By Paul Buckley
Linear Technology Corporation has introduced a surge stopper with ideal diode, providing compact and low-loss protection for 4 V to 80 V electronics in automotive, avionics and industrial systems.

The LTC4364 surge stopper shields downstream electronics from input overvoltages and overcurrent, enabling continuous operation through transient surges. Overcurrent limiting protects the system and supply from short-circuits at the load. Unique to the LTC4364 is ideal diode control, which replaces a Schottky diode in the power path with a low loss N-channel MOSFET. The ideal diode, along with a robust front-end, protects the load from a reversed input down to -40 V and maintains the output voltage during an input brownout.

During an input voltage surge, such as automotive load dump, the LTC4364 drops the excess voltage across an external MOSFET while regulating the output to an adjustable safe voltage. This enables the use of lower voltage rated electronics downstream. Similarly, during a current surge, the LTC4364 regulates the forward path to a current limit set by a sense resistor. For persistent overvoltage or overcurrent conditions, a VDS-accelerated timer with early warning indicator ensures safe shutdown of the MOSFET.

The LTC4364’s wide operating range maintains operation in automotive cold crank when the battery voltage could dip down to 4 V. With a simple input clamp, the device can handle transient surges beyond 100 V and can even survive -20 V at the output. The latter, along with diode blocking and overcurrent limiting, makes the LTC4364 a complete solution for protecting output ports. Adjustable input undervoltage and overvoltage thresholds block start-up for out-of-range voltages, avoiding deeply discharged batteries and auto-retry into a fault condition. A low 370 µA operating and 10 µA shutdown current prolongs battery life. The device can also be used for inrush current control, providing HotSwap capabilities.

Availability and Pricing

The LTC4364 is available in two options. After a fault, the LTC4364-1 latches off the pass transistor, whereas the LTC4364-2 enables a 0.1% duty cycle auto-retry. Specified over the full commercial, industrial and automotive temperature ranges, the LTC4364 is offered in 14-pin DFN (4mm x 3mm), and 16-lead