Linear Technology’s surge stopper ICs from Astute protect against high voltage transients


Eliminates or reduces size of heatsink required

July 2016: Astute Electronics, the leading supplier of electronic components and value added

services, has introduced Linear Technology’s high efficiency LTC7860 surge stopper ICs which protect

loads from high voltage transients. 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),

the LTC7860 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.

Comments Ian Fantham, Sales Director, Astute Electronics: “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 that the LTC7860 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 optimized 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.