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TPS5130 doesn't start with slow ramping input

Muzaffer Kal
Prodigy 50 points
Other Parts Discussed in Thread: TPS5130

I have a design which implements the TPS5130 and I have a problem where if the power supply behind me has a slow ramping output TPS5130 doesn't start at all. If I turn on the previous power supply (at 13.8 volts) and push the power button on my board later, TPS5130 starts and generates the voltages I need.

So far I checked the reference output at .85 and the internal regulator outputs which are OK even when the controller doesn't start. Any idea why a TPS5130 doesn't give switched dc output when the input voltage is ramping very slowly?

 

  • 0
    Prodigy 50 points

    here is some more info: If I short the FLT pin to ground, TPS5130 starts regardless of how slow the input ramps.

    To summarize, the design works with several power supplies at the input and fails to start with one specific power supply if power switch is on while the input supply is starting. If the design's power switch is off while the input supply is coming up and then switch is closed after input power supply ramps, TPS5130 also works.

    It seems that the TPS5130 gets into a fault condition and can't get out even when the fault cause goes away (as the problem doesn't happen if fault is suppressed).

    Any idea how to get around this?