Hello
I'm using the LM25116 at the heart of a small 2A out regulator, the output voltage of which has to have some flexibility depending on an injected input voltage. I made the voltage variable in two ways. First I used a pot R432 (R411 is in parallel but it is not populated on the board) the pot ideally would let me set the inital highest voltage, and then I could inject a voltage below 1.215 volts into the SS pin to lower the voltage even further for my application. Now my problem is this, no matter what value I set to the pot or the voltage I inject into the SS pin the voltage is always a constant around 6V. I've worked on this for a little bit and have not been able to figure out the problem. The eval board I first modeled this circuit on works, and I am at a loss at the moment for why this is failing. Below is a copy of my schematic
Edit: 2014/02/05 3:58PM EST
Another unusual behavior I have observed is that with any voltage above 0.08V on the SS pin give me around 6V out, however if reduce it beyond that the voltage drops to 2.5V, and if i don't connect anything to the SS pin the voltage also goes to 2.5V the only time I can get it above that is by injecting a signal of over 0.08V.
