Surge stopper ICs protect against high voltage transients

Protecting loads from high voltage transients, the LTC7860 surge stopper IC from Linear Technology is now available from Astute Electronics.

During an input overvoltage event, such as a load dump in vehicles, the LTC7860 controls the gate of an external MOSFET to act as a switching DC/DC regulator (PROTECTIVE PWM mode). This operation regulates the output voltage to a safe level, allowing the loads to operate through the input over-voltage event.

During normal operation (SWITCHON mode), this surge stopper IC turns on the external MOSFET continuously, passing the input voltage through to the output. An internal comparator limits the voltage across the current sense resistor and regulates the maximum output current to protect against overcurrent faults.

Ian Fantham, sales director, Astute Electronics said:  “Traditionally, designers need to include a large, heavy heatsink to allow operation to continue, just for the rare over-voltage instances. Because the LTC7860 uses an efficient switching topology, designers can use a much smaller heatsink, or no heat sink at all.”

Available in small, thermally enhanced 12-lead MSOP packaging, the devices feature an adjustable timer, which limits the time the surge stopper IC can spend in overvoltage or overcurrent regulation.

When the timer expires, the external MOSFET is turned off until the LTC7860 restarts after a cool down period. By strictly limiting the time in PROTECTIVE PWM Mode when the power loss is high, the components and thermal design can be optimised for normal operation and safely operate through high voltage input surges and/or overcurrent faults. An additional PMOS can be added for reverse battery protection.

Applications include military power systems to MIL1275, ISO7637 vehicle systems and general power supplies for industrial and telecoms equipment.

http://www.astute.co.uk

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