Analog Devices LTC7862

Description

The LTC®7862 high efficiency switching surge stopper protectsloads from high voltage transients. High efficiencyswitching allows high output currents, small solution sizes,and high reliability. During an input overvoltage event, theLTC7862 controls the gates of two external N-channelMOSFETs 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 inputovervoltage event. During normal operation, the LTC7862turns on the top external N-channel MOSFET continuously,passing the input voltage through to the output, with minimalvoltage drop. Using a fast peak current comparator,the LTC7862 also limits the maximum output current toprotect against overcurrent and short-circuit faults.An adjustable timer limits the time that the LTC7862 canspend switching during an overvoltage, overcurrent, orstartup condition. When the timer expires, the externalMOSFETs are turned off for a cooldown period and thenthe LTC7862 restarts. By strictly limiting how long theLTC7862 can switch, when the power loss is relativelyhigh, the components and thermal design can be optimizedfor normal pass-through operation while still safelyoperating through high voltage input surges and/or overcurrentevents.

Features

• 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 900kHz
• Adjustable Input Voltage Turn-On Threshold
• Adjustable Input Overvoltage Lockout Threshold
• 20-Pin 4mm × 5mm QFN and TSSOP Packages

Typical applications

• Vehicle Power Including ISO7637 / Military Power Including MIL1275
• Automotive/Avionic/Industrial Surge Protection / Automotive Load Dump Protection

More information

• Datasheet
• IC product information