> Can someone recommend a low-Vf diode for diode-OR

At very low currents I think most/all Schottkeys are low Vf

For example the SB1245 I looked at recently for a power
application is described as "Ultra Low Vf". At mA current
Vf is down around 20mV

www.fairchildsemi.com/ds/SB/SB1245.pdf

Compare with a signal diode like a BAT46

http://www.vishay.com/docs/85662/bat46.pdf

mA current, Vf also around 20mV

A 1N4148, which I've used many times with a back-up SRAM,
has "insignificant" Vf at retention current (< 10uA) but may be a
little high at operating current (~30mA + pin loading) if Vcc is 3V

http://www.nxp.com/documents/data_sheet/1N4148_1N4448.pdf

Joe
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