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.