Hello.
I have a board which uses five of the TPS40200 chips to make rails at 5.0V, 3.3V, 2.5V, 1.8V, and finally 1.2V
I have the first four rails working fine, but the 1.2V rail is very fickle.
I have designed using SwitcherPro, 
C9 has been changed from 4.7uF to 220 uF.
Now here is what I have discovered so far about the1.2V rail:
The chip is on. I can see voltages at all the pins. My soft start signal looks identical to the other 4 working chips.
I'm seeing Vin at my gate drive pin, but no signal like I do with the other 4 devices.
I see 0.85V at feedback, as opposed to 0.725V with the other 4 devices
I see 0.0615V at comp, as opposed to roughly 1 volt (.996V - 1.02V depending on the Vout of the other rails)
Now here is where things get annoying. When I rework the board or troubleshoot, sometimes the 1.2V rail will turn on for a few seconds. If I use rosin and alcohol cleaner, and leave it on the board, 1.2V works indefinitely, and I see an identical gate signal and switching signal. when I clean the board using a sonic bath, I go back to no output, no gate signal.
If anybody has an idea to help me, I would appreciate it.
