Efficient Power Supply ORing & Supply Holdup in new Dual Ideal Diode Controller from Linear

The LTC4353 regulates the forward voltage drop across external N-channel MOSFETs to ensure smooth current transfer between supplies in diode-OR applications. In low voltage systems, a slow handoff between controllers results in a voltage droop during supply switchover. The fast <1µs turn-on time of the LTC4353 ensures smooth switchover from one path to the other without oscillation. In the event the input supply fails or is shorted, a fast turn-off minimizes reverse current. In addition to redundant power supply ORing, the LTC4353 makes an excellent diode replacement in supply holdup applications where momentary collapse of supply voltage is isolated from the load.

The LTC4353 provides individual enable inputs that can be used to ensure priority to the main supply when supply voltages are within a MOSFET body diode drop of each other. With both enable inputs pulled low, the LTC4353 consumes just 75µA per supply. Individual status outputs indicate whether the MOSFETs are on or off. The controller operates with supplies from 2.9V to 18V, and offers additional flexibility to control voltages down to 0V by applying an external supply.

The LTC4353 is the only dual low voltage ideal diode controller available on the market, offering significant space savings compared to competing solutions. The LTC4353 is offered in both 16-Lead MSOP and 4mm x 3mm DFN packages and is specified over the commercial and industrial temperature ranges. Pricing starts at $3.45 each in 1,000 piece quantities.

Summary of Features: LTC4353
• Low Loss Replacement for Schottky Power Diodes in Multiple Power Supply or Supply Holdup Applications
• Controls External N-Channel MOSFETs for High Current Capability
• 0V to 18V Supply ORing or Holdup
• 1µs Turn-On & Turn-Off Time
• Enable Inputs
• MOSFET On-Status Outputs
• Available in 16-Pin MSOP & DFN
(4mm x 3mm) Packages