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TPS65130: Getting -15v instead of -2.4v please help

Blane Townsend
Prodigy 10 points
Part Number: TPS65130


Hi, I designed an ordered my board and have tested several of them now. It is for a smart watch and I'm trying to power my AMOLED screen so I need +4.6v and -2.4v output. The +4.6v output works as expected, but instead of getting -2.4v I'm getting -15v and I can't figure out why? I've added my schematic here if you can take a look at it with the values of the resistors and capacitors. One thing I did notice is the voltage at VREF is 0.0v instead of 1.213 like it says in the docs. What would cause that or is that a red herring?

 

  • 0
    Prodigy 10 points

    Ok the 100ohm resistor R1 in my diagram was causing the voltage to drop from 3.3v to 2.5v and so the ENP, PSP, ENN, PSN were not on. I removed the 100ohm resistor entirely and then it output -2.4v. However, once I attached my screen the voltage then changed to -1.2v. As soon as I attach/detach the screen the voltage changes between -2.4v and -1.2v. Also when it's outputting -1.2v the VREF drops to 0.26V and FBN is 0.0v. What would cause this to happen?