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TPS65011 in a "stuck" condition

Garrett Clark
Prodigy 50 points
Other Parts Discussed in Thread: TPS65011

We are seeing an intermittent error condition with the TPS65011, where it is essentially "stuck" in a state where all the converters are on but the MPU_RST line is never released so our processor never runs. This happens infrequently, but when it occurs there is no way to get past the problem without disconnecting the battery. It appears that battery charging is still working properly if the device is plugged-in to USB. Also, the voltages all seem to be correct.

Design details:

Device is charged through USB only

VMain is 3.3v, VCore is 1.8v, LDO1 is 1.2v (supplied by VCore)

Device is turned on with PB_ONOFF, or when attached to USB

Device is turned off by setting VDCDC1 bits 3 and 4, then raising LOW_PWR

The following pins are not used (unconnected): HOT_RESET, RESPWRON

  • 0
    TI__Genius 17240 points

    Can you be more specific about when exactly the error condition occurs in reference to Figure 31 of the datasheet?

    Also, I would like the schematic, layout and a scope shot of Vmain for both a good and bad board.

    You can post the schematic and layout, start a "conversation" or I can provide my email. 

    Thanks!

     

  • 0 in reply to Daniel Acevedo
    Prodigy 50 points

    Here is where we seem to be stuck. RESPWRON and MPU_RESET are always low. Actually, RESPWRON floats near low.

    Here is an excerpt of the schematic:

    VMain looks the same (3.3v) whether the board is glitched or not. I'm having trouble getting it into a failure mode at the moment, so I don't have a scope image for you.

    Thanks for the quick reply!

  • 0 in reply to Garrett Clark
    TI__Genius 17240 points

    Were you able to get the requested scope shots? Will you please illustrate in which state you are stuck in and please reference figure 31 of the datasheet (not figure 33 as you in your post)? Is this on the first power-up? If not, how did you last shut-down to get in this state? What surrounding ICs are in the system and have the inputs/outputs of these been verified?

  • 0 in reply to Daniel Acevedo
    Prodigy 50 points

    Here is VMain (3.3v) of a device in the glitched state. Looks fine to me, and VCore and LDO1 are also fine.

    Here is VMain from working device, as you requested:

    Here is RESPWRON, which is apparently not being held low any longer. It is floating near low, but when it's active it actually sits at the 0v line.

    As best as I can tell, this is where we are in the state diagram. Everything is ON but MPU_RESET is held low and so the processor never starts.

    The processor we are using is an ARM9 from Atmel called the AT91SAM9R64. As I've stated, the processor isn't running because the PMU is holding down its reset line. The only input from our processor other than I2C is the LOW_PWR line, which is low as it should be.

    The units we have that have glitched this way typically are being returned from customers, so they have all initially worked and been QA tested. Some have worked for weeks before this happens, but when it does they have all had the exact same symptoms. Our shutdown process is to set the VDCDC1 register bits 3 and 4, then raise LOW_PWR. 

  • 0 in reply to Garrett Clark
    TI__Genius 17240 points

    I'm looking into this.

    What is the power configuration at the time of the failure? Is it when USB and BAT are connected, just USB or Just BAT or any combination? Also, the pull-up for /MPU_RESET is  probably on another page of the schematic but what do you have it pulled up to?

     

     

     

  • 0 in reply to Daniel Acevedo
    Prodigy 50 points

    Thanks for helping dig into this issue. We know for certain the glitch happens when USB is both connected and unconnected, and our BAT is always connected. I can also tell you that the batteries have had a good charge. The MPU_RESET line is connected to our processor's NRST line which has an integrated 100K pull-up.