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1.2A Overvoltage/Overcurrent Protector Isolates Sensitive Low Voltage Electronics from Input Power Surges

24th June 2010

Linear Technology (UK) Limited

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Datasheet

Linear Technology Corporation introduces the LTC4362, a 2.5V to 5.5V overvoltage and overcurrent protector designed to safeguard low voltage, portable electronics from damaging input voltage transients and current surges. Overvoltage events can occur due to power adapter failure or faults, or when hot-plugging an AC adapter into a device's power input. Inadvertently plugging the wrong power adapter into a device can potentially cause damage from overvoltage or negative supply voltage. The LTC4362 utilizes a 2% accurate 5.8V overvoltage threshold to detect an overvoltage event and responds quickly within 1µs (max) to isolate the downstream components from the input.

Overvoltage protection of up to 28V is achieved with an internal, avalanche rated, low RDS(ON) MOSFET, and rides through inductive cable transients without requiring transient voltage suppressors (TVS) or other external components in most applications. In addition, the LTC4362 monitors the voltage drop across an internal current sense resistor to provide a 20% accurate, 1.5A overcurrent threshold. The LTC4362 is targeted for portable electronics with multiple power supply options, such as cell phones, MP3/MP4 players, digital cameras that charge via wall and car battery adapters and USB ports.

The LTC4362 controls an internal 40mOhm N-channel MOSFET so that under normal operation it provides a low loss path from the input to the load. Inrush current limiting is achieved with a controlled gate voltage slew rate. If the voltage at the input exceeds the overvoltage threshold of 5.8V, the GATE is pulled low within 1us to protect the load. The LTC4362 features a soft shutdown controlled by the /ON pin and provides a gate drive output for an optional external P-channel MOSFET for reverse voltage protection. A power good output pin indicates gate turn on. The LTC4362 is available in two options; the LTC4362-1 latches off after an overcurrent event, whereas the LTC4362-2 performs an auto-retry following a 130ms delay. Following an overvoltage condition, both options automatically restart with a start-up delay.