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TPS62290 Failure

Andres Bergeret
Prodigy 100 points
Other Parts Discussed in Thread: TPS62290

Hi!

I've had the same TPS62290 failure in 3 boards already and I'm trying to figure out the problem so I can redesign it if needed.

The part powers the I/O of an FPGA. When I noticed the FPGA was down, I measured the resistance between the 3.3V pins and it was only 2.3 ohms.

I replaced the TPS62290 and it outputted 3.0 V for a while and then failed again.

I thought that maybe it was outputting too much current, but I removed the chip and connected a power supply and it was only 0.3A.

Do you have any idea of what might be happening? I'd be happy to provide any further information that might help diagnose the problem.

Thanks!

Andres

  • 0
    Expert 1920 points

    Ref. http://www.ti.com/lit/ds/symlink/tps62290.pdf page 14 figure 21, try to connect the MODE pin to GND instead of Vin.

  • 0
    TI__Guru**** 150930 points

    Since these are very simple and integrated ICs, typical problems include board layout and/or excessive output capacitance.  Could you post your board layout?

    These ICs also have a very strict output capacitance limit, as described in the datasheet, due to the internal loop compensation.  The output capacitance is the total capacitance on the output, not just what is on this page of your schematic.  The IC sees it all.  My guess is that with an FPGA load, you have much more Cout downstream.  This makes the IC unstable and could lead to failure.

    By placing the IC close to the load and thus removing the inductance, much of this capacitance can usually be safely removed without decreasing the FPGA's performance.

  • 0 in reply to Chris Glaser
    Prodigy 100 points

    Thanks for the advice, Chris!

    I can't post the board layout, but I'll measure the seen capacitance tomorrow and let you know what I find.

    Regards,

    Andres