Features

• Power Path and Inrush Current Control for Redundant Supplies
• Low Loss Replacement for Power Schottky Diodes
• Protects Output Voltage from Input Brownouts
• Allows Safe Hot Swapping from a Live Backplane
• 2.9V to 18V Operating Range
• Controls N-Channel MOSFETs
• Limits Peak Fault Current in ≤1μs
• Adjustable Current Limit with Circuit Breaker
• Adjustable Current Limit Fault Delay
• Smooth Switchover without Oscillation
• 0.5μs Ideal Diode Turn-On and Turn-Off Time
• Status, Fault and Power Good Outputs
• LTC4228-1: Latch Off After Fault
• LTC4228-2: Automatic Retry After Fault
• 28-Lead 4mm × 5mm QFN and SSOP Packages

Typical Application

Description

The LTC®4228 offers ideal diode and Hot Swap™ functions for two power rails by controlling two external N-channel MOSFETs in each rail. MOSFETs acting as ideal diodes replace two high power Schottky diodes and the associated heat sinks, saving power and board area. Hot Swap control MOSFETs allow boards 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 current limit and internal timed circuit breaker.

The LTC4228 regulates the forward voltage drop across the external MOSFETs and sense resistor to ensure smooth current transfer from one supply to the other without oscillation. The ideal diodes turn on quickly to reduce the load voltage droop during supply switch-over. If the input supply fails or is shorted, a fast turn-off minimizes reverse-current transients.

The LTC4228 allows independent on/off control, and reports fault and power good status for the supply. The LTC4228 improves on the LTC4225 by recovering more quickly from input brownouts to preserve the output voltage.