Ideal diode controller suits low voltage applications

Low voltage applications where a slow handoff by controllers can result in a voltage droop during supply switchover could benefit from Linear Technology's LTC4352, a 0V to 18V ideal diode controller that smoothes current transfer between supplies in diode-OR applications.

The LTC4352 regulates the forward voltage drop across an external N-channel MOSFET.A charge stored on an external capacitor for immediate sourcing of gate pull-up current enables a fast turn-on time of 500ns, which Linear says results in the LTC4352 being able to control the switchover from one path to the other without oscillation. Meanwhile, if an input supply fails, a fast turn-off minimises reverse current. For this reason, the LTC4352 can act as a diode replacement when a load needs to be isolated during a momentary collapse of supply voltage.

The LTC4352 provides under/over voltage monitoring and a FAULT# pin to indicate when the input supply is outside of proper levels or an open MOSFET fault has occurred, while a STATUS pin indicates the MOSFET on state. The ideal diode behaviour may be overridden to allow reverse current if required. This part can be used for inrush current control in applications where the input supply is hot-plugged.

Compared to a standard diode, the LTC4352 prevents out of range input voltages from affecting the load voltage by using back-to-back MOSFETs and resistive dividers on the UV and OV pins to set the allowable input voltage operating range.

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 LTC4352 comes in 12-pin MSOP and 3mm x 3mm DFN packages and is specified over the commercial and industrial temperature ranges.

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