LTC4411 - Schottky diode selection for automatic power switch over

I'm in the process of designed a simple power supply OR switch using the LTC4411.  The main supply is regulated 3.3V from a battery while the secondary source is a regulated 3.3V supplied via a 12V wall adapter. 

I have trouble properly selecting the schottky diode that is recommended in the applications notes from the data sheet.

Thanks

  • Hi,  The Schottky diode needs to have a reverse breakdown greater than 3.3V (plus margin) and should be rated for your load current. Note that a 0.3V or 0.5V Schottky diode drop can eat up a significant portion of your 3.3V supply (10% to 15%). It may be better to use the LTC4413 dual ideal diode for your application.