Diode ORing for system power

Discussion in 'The Projects Forum' started by rakeshm55, Feb 21, 2011.

  1. rakeshm55

    Thread Starter Member

    Oct 19, 2010
    Which will be a suitable schottky diode for Diode ORing ?? I need to switch b/w adaptor power and Battery power
    Adaptor power is 5V Dc..
    Battery is lithium ion 4.2-3V.....
    System load is not more than 40mA......
    I want the system to switch to battery power in adaptor is OFF.....
    Wat are the techniques available....

    For Diode ORing are there any readymade chips available......
  2. Wendy


    Mar 24, 2008
    All diode ORing is a pair of diodes where the power supply with most voltage conducts through.

    The only reason a Schottky diode is used is it drops around 0.2V vs the 0.6V a silicon diode drops.

    Any diode will work, Schottky better than conventional. A chip for 2 diodes... I've seen pairs of Schottky's package in 3 terminal packages. They were high power though, so the package was massive. You can buy small low power Schottkys in small packages, or even use low power germanium diodes, so what's the point?
  3. SgtWookie


    Jul 17, 2007
    Use a pair of 1N5817 through 1N5819 (rated for 1A avg. current), or 1N5820 through 1N5822 (rated for 3A avg. current). These Schottky diodes have a very low forward voltage for the current you say you will be using.