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ADS7253: ADS7253 data conversion erro

Eric QI
Intellectual 620 points
Part Number: ADS7253

Hi,

Now I'm using ADS7253 for converter analog signal of current to digital signal.

The current is the phase current of inverter.

The problem is ,when current increases,so does the noise.

And the conversion of ADS7253 is error.

As shown below,all of the data move one bit to the left.

I want to know,whether this phenomenon is related to power noise or ground noise.

Or is there any other reason.

Thanks.

channel 2: CS

channel 3:SDO

  • 0
    TI__Guru 57336 points

    Hi Eric, 

    Thank you for your post.

    It's impossible to make any sense of this data without seeing the SCLK waveform captured with SDO_x. We will need more details about this measurement, such as the applied input voltage to the ADC and what data values are being ready by your host controller.

    Also, please provide a schematic showing the input signal chain and the ADS7253 connections.

    Best regards,

  • 0 in reply to Ryan Andrews
    Intellectual 620 points

    Hi,Ryan

    The data is shown below.Apparently, the SCLK was disturbed.

    Channel 1: SCLK

    Channel 3 :SDO

  • 0 in reply to Eric QI
    TI__Guru 57336 points

    Hi Eric,

    Clearly there is some noise that is coupling across your digital communication signals. My suggest is to add some capacitance from each signal to ground. This will filter some of the high frequency content and reduce the noise coupling.

    The "bit shift" might be explained by the extra glitch you see on the SCLK waveform. This could cause your MCU to latch the data prematurely.

    Regards,