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ADS1299-4: The shorted input waveform is not correct and has a sudden rise

Cherry Zhou
Mastermind 22235 points
Part Number: ADS1299-4
Other Parts Discussed in Thread: ADS1299

Hi team,

Here's an issue from the customer may need your help:

Gain is 1 and sampling rate is 250sps. 

There is a sudden rise as the following figure on the waveform, why's this? It should not be a problem with signal transmission since the customer had test the internal square wave signal of the chip, which is good.

Could you help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Mastermind 19815 points

    Hi,

    May I ask which customer? If cannot be disclosed, please convert the thread to INTERNAL.

    ----------------------------------------------------------------------------

    With little information, it's hard to help debug and troubleshooting, BUT

    You said - "customer had test the internal square wave signal of the chip, which is good."   -- This is great. that means the noises spikes&glitches may not be from the chip itself, could be from the PCBA.

    ------------------------------------

    Here might be some guidance questions and something customers could try-

    0. Is customer using an EVM or their own customer PCBA?

    1. what are customer's signal source(s) and signals(s) they use to input the ADS1299? Is that source and signal clean? It's suggested if they could get an ECG simulator as a reference for test.

    2. Have they try to set the input channel to "internal short" and to see what happen?

    3. If they are using customer PCBA, they may need to double check their layout make sure the analog portion/tracks are far away from any digital or high speed signals.

    4. also check the electrodes, patches, wiring, cabling, shielding, etc, i.e. any thing from and along the signal source(s) to the ADS1299 analog input(s).

    Thanks