140V High Efficiency Switching Surge Stopper

The LTC7862 high efficiency switching surge stopper protects loads from high voltage transients. High efficiency switching allows high output currents, small solution sizes, and high reliability. During an input overvoltage event, the LTC7862 controls the gates of two external N-channel MOSFETs to act as a switching DC/DC step-down regulator. This maintains the output voltage at a safe value, allowing the loads to continue to operate through the input overvoltage event. During normal operation, the LTC7862 turns on the top external N-channel MOSFET continuously, passing the input voltage through to the output, with minimal voltage drop. Using a fast peak current comparator, the LTC7862 also limits the maximum output current to protect against overcurrent and short-circuit faults.

An adjustable timer limits the time that the LTC7862 can spend switching during an overvoltage, overcurrent, or startup condition. When the timer expires, the external MOSFETs are turned off for a cooldown period and then the LTC7862 restarts. By strictly limiting how long the LTC7862 can switch, when the power loss is relatively high, the components and thermal design can be optimized for normal pass-through operation while still safely operating through high voltage input surges and/or overcurrent events.

Applications

* Automotive/Avionic/Industrial Surge Protection

* Automotive Load Dump Protection

* Vehicle Power Including ISO7637

* Military Power Including MIL1275

* VOUT Clamp Stops High Voltage Input Surges

* 100% Duty Cycle Pass-Through Mode During Normal Operation

* Switches During Overvoltage or Overcurrent Transients and Faults and During Startup

* High Efficiency Switching Enables Long Duration Surge Protection and High Output Currents

* Wide VIN Range: 4V to 140V (150V Abs Max)

* Adjustable Output Voltage Clamp Up to 60V

* Adjustable Output Overcurrent Protection

* RSENSE or Inductor DCR Current Sensing

Power Inductor Reduces Input EMI in Normal Mode

* Adjustable Soft-Start for Inrush Current Limiting

* Programmable Fault Timer

* Open-Drain Fault Warning Indicator

* 2.7% Retry Duty Cycle During Faults

* Adjustable Switching Frequency: 50kHz to to 900kHz

* Adjustable Input Voltage Turn-On Threshold

* Adjustable Input Overvoltage Lockout Threshold

* 20-Pin 4mm × 5mm QFN and TSSOP Packages