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Original question:

TLV5632IDW sensitivity

TLV5632: Internal hang up

Herbert Madeja
Prodigy 20 points
Part Number: TLV5632

Hello - I have the same problem with the chip by ESD like the thread "TLV5632IDW sensitivity" Only by ESD pulse about +/ 7kv all the analog output will be going to 0V. And it is not possible to update the DAC output. If the Error occurs, I have checked the signals from the uC / SPI. The SPI Command (SCLK, FS, DIN) include the timing are ok. Also the expected Data are correct. The GPIO Bits (LDAC, PRE) also ok. We have tried a software reset to exclude an error in the software. After the SW Reset the error was still present. Only if I shut down the VCC Power the chip will reworking correct. It seams that the chip have an internal hang up so they will no more understand any software orders. What is the problem and what can i do that the chip will working correct again? 

schematics

  • 0
    TI__Guru 53773 points

    Hi,

    Are you trying to qualify this device or system to some kind of ESD level?  Our devices are only qualified to certain HBM and CDM ratings.  I need to look up the qualification level for this, but I doubt we test HBM to 75kV on this.  It is possible you are damaging the device as well.

  • 0 in reply to Paul_Frost
    Prodigy 20 points

    Hello again,

    The device will be tested by +-7KV not 75KV. It must be reach 12KV air discharge. In any case, the device is not defective. It works perfectly again after a new power up.  I can now try to make the device ESD tighter, but the problem with the hanging DAC is still present. Therefore, I am looking for a solution that the DAC does not hang up or how to get it running again via software.

     

  • 0 in reply to Herbert Madeja
    TI__Guru 53773 points

    Hi, Sorry, I means 7.5kV is still higher than the level we qualified this device : 2KV HBM and 750V CDM. 

    There could be a lot reasons this might happen.  This test is violating our absolute maximum voltage ratings and while it might not be overtly damaging the device, it could be causing some latent issues.  Ultimately I recommend you implement additional transient voltage protection on the device.  What pins are you applying this spike? 

    Thanks,

    Paul

  • 0
    Prodigy 20 points

    hello, This is not a problem of the ESD strength at the pins, rather the ESD strength of the device according to CE conform and EN60601-1-2. The achieved level of +-7KV is not decisive.It is basically about the fact that the DAC no longer applies the values at the analog output, which are transferred to it via the SPI bus, after an ESD pulse.  It shows that the internal logic of the device does not work properly anymore, so that no transmitted value is transferred to the output.Only a power up, which is roughly equivalent to a hardware reset, brings the chip back to life. Regardless of the ESD level, the main problem is that the device is no longer responsive and it does not have its own reset input to bring it back to life. Therefore the question whether there is a solution on the part of TI. The very best solution is a workaround via software if possibility.

  • 0 in reply to Herbert Madeja
    TI__Guru 53773 points

    Hi,

    So to clarify, you are doing this the whole system, not just the TLV5632? 

    I am not sure what exactly is causing the TLV5632 to lock up, but it is possible there is some kind of brownout event in the device from AVCC momentarily collapsing.  I recommend you approach from two different paths:

    1. See you can attenuate the stress on the device by implementing additional power supply filtering (ferrite beads, high fC RC filtersin, additional supply decoupling) and additional power supply protection in the form of TVS and ESD diodes.

    2. You can try disconnecting DVDD from the VCC supply and drive it directly with a GPO pin from your MCU.  THis pin only needs a few mA to operate, so it is possible you could use the GPO as a combination DVDD/RESET pin.  That might allow the device to recover.

    I am not aware of any internal register that can be used to reset the device internally.

  • 0
    Prodigy 20 points

    Another hello. So, now we are a bit further. We have tried to change the signal from high to low and back to high via software at the PRE pin when the error is present. With this, the DAC accepts the data correctly again when the analog values are reloaded.  All other pins bring no success. There seems to be an internal malfunction with the preload register, so that the default value is always emitted and the SPI interface therefore does not react anymore.
    Now an extended question: Is it possible to outsmart the internal logic with this software trick, so that the device works correctly again without a physical reset signal? A change of the hardware is unfortunately no longer possible with this product.

  • 0 in reply to Herbert Madeja
    TI__Guru 53773 points

    Hi Herbert,

    It is difficult to say for sure if there is a way to recover from this condition, as I am not sure what exactly is halting the internal logic.  It is interesting that the PRE pin recovers this behavior.  I would be would an interesting experiment to try to implement additional protection on that pin to see if it is root of the failure.  I think if you cannot implement any other hardware changes, then you should leverage this PRE toggle for recover.  I suspect that the PRE pin will clear the input register at a hardware level and likely causes a partial logic reset.