Dual Ideal Diode and Single Hot Swap Controller

The LTC4227 offers ideal diode-OR and Hot Swap™ functions for two power rails by controlling external Nchannel 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 current limit and internal timed circuit breaker.

The LTC4227 regulates the forward voltage drop across the MOSFETs 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 switchover. If the input supply fails or is shorted, a fast turn-off minimizes reverse-current transients.

The LTC4227 allows turn-on/off control, and reports fault and power good status for the supply.

Part

Overcurrent Fault

Start-Up Delay

LTC4227-1

Latch Off

100ms

LTC4227-2

Retry

100ms

LTC4227-3

Latch Off

1.6ms

LTC4227-4

Retry

1.6ms

Applications

* Redundant Power Supplies and Supply Holdup

* Computer Systems and Servers

* Telecom Networks

* Power Path and Inrush Current Control for Redundant Supplies

* Low Loss Replacement for Power Schottky Diodes

* Allows Safe Hot Swapping from a Live Backplane

* 2.9V to 18V Operating Range

* Controls N-Channel MOSFETs

* Limits Peak Fault Current in ≤1μs

* 0.5μs Ideal Diode Turn-On and Reverse Turn-Off Time

* Adjustable Current Limit with Circuit Breaker

* Smooth Switchover without Oscillation

* Adjustable Current Limit Fault Delay

* Fault and Power Status Output

* 20-Lead 4mm × 5mm QFN and 16-Lead SSOP Packages