I have a design that will run off of a single cell 1.5V AA battery and I wanted to provide some reverse battery protection to it while also maximizing my run time. The classic way to do this is just with a FET.
But then I was reading a TI app note where they note that when a battery is drained to 0.8V the voltage is not sufficient to fully turn on the FET and it will operate in the linear region. Therefor the RDSon is much higher and the voltage drop will not allow the regulator (which is placed after the protection) to turn on.
Their solution in the app note is a regulator they have with a Vaux output that charges up to 2.5V before turning on the main output. This Vaux pin is used to pull up the gate of the FET thus turning it on. The part they use is a little too small for me and I was trying to figure out a way to get just this feature discretely or with some additional IC.
Has anyone run into an application like this before or have any advice?
I looked for some charge pumps but they stopped around 0.9V input where I want to get down to 0.7V (their circuit can do 0.5). I looked for some other regulators and I've considered using their regulator just for it's vaux capability :) Finally one AA battery is a hard requirement, I don't have a choice here.