hey guys, i'm now doing a negative power supply by using a buck-boost system. It works pretty well that it gives a negative 5V with a 5V DC input. Here's the problem, i'm trying to measure the output resistance of the system by treating the system as a thevenin's equivalent circuit, the thevenin's voltage source of which is -5V (as when the load resistance is really large, say, 15Mohms, the voltage at the load is -5V). I measured the current flowing through the load and voltage at the load with different load resistance and calculate output resistance of the system, and it turned out to be different for different load resistance. and i found that the output resistance increases as i decreases the load resistance value.
anyone has any idea on how this could happen??
here's a link to the intro to buck boost thing on wikipedia: (and we are doing exactly the same thing)
http://en.wikipedia.org/wiki/Buck–boost_converter
thanks
anyone has any idea on how this could happen??
here's a link to the intro to buck boost thing on wikipedia: (and we are doing exactly the same thing)
http://en.wikipedia.org/wiki/Buck–boost_converter
thanks