Features

• Ideal Diode-OR and Inrush Current Control for Redundant Supplies
• Low Loss Replacement for Power Schottky Diodes
• Enables Safe Board Insertion into a Live Backplane
• 2.9V to 18V Operating Range
• Current Monitor Output
• Controls N-Channel MOSFETs
• Limits Peak Fault Current in ≤ 1μs
• Adjustable Current Limit with Foldback
• Adjustable Start-Up and Current Limit Fault Delay
• 0.5μs Ideal Diode Turn-On and Turn-Off Time
• Smooth Switchover without Oscillation
• Fault, Power Good and Diode Status Outputs
• LTC4236-1: Latch Off After Fault
• LTC4236-2: Automatic Retry After Fault
• 28-Pin 4mm x 5mm QFN Package

Typical Application

Description

The LTC®4236 offers ideal diode-OR and Hot Swap functions for two power rails by controlling external N-channel MOSFETs. MOSFETs acting as ideal diodes replace two high power Schottky diodes and the associated heat sinks, saving power and board area. A Hot Swap control MOSFET allows a board to be safely inserted and removed from a live backplane by limiting inrush current. The supply output is also protected against short-circuit faults with a fast acting foldback current limit and electronic circuit breaker.

The LTC4236 regulates the forward voltage drop across the ideal diode MOSFETs to ensure smooth current transfer from one supply to the other without oscillation. The ideal diode MOSFETs turn on quickly to reduce the load voltage droop during supply switchover. If the input supply fails or is shorted, a fast turn-off minimizes reverse current transients.

A current sense amplifier translates the voltage across the sense resistor to a ground referenced signal. The LTC4236 provides adjustable start-up delay, turn-on/-off control, and reports fault and power good status for the supply.