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TPS7A47 and TPS7A33 Split Power Supply not working

user4922893
Prodigy 30 points

Hello,
i want to use a 35 Volt DC wall adapter to create a +-15Volt supply with virtual ground.
The pspice model works but in real only the -15 Volt rail works.
The +15Vdc rail shows only +2.5 Volt. It seems that the ground is not centered.
I don't know how pspice is handling the ground issue on V3 and V4. Maybe the regulators are fighting to each other.
I have seen some split supply solutions with 1R load resistors but schematic was complete different.
Can someone help with an correct schematic idea?

Here is the my pspice model scheme i have build:


Big thanks!

  • 0
    TI__Guru 55940 points
    Hi ,

    Many times in a split rail system, if the negative rail starts up before the positive rail, the positive rail will not properly start up. The cause of this is that the negative rail pulls the positive rail's output negative. Often this can be solved with a simple modification to the existing circuit. Options include delaying EN for the negative rail with an RC or code or even having a larger NR/SS capacitor on the negative rail.

    Very Respectfully,
    Ryan