ADS8678: Low side current sensing application suitability

Steven Shenker

Part Number: ADS8678

Hi there,

I am wanting to use this part for a current sensing application of 0-9V range with current sensing of 0-3A (0.3 ohm resistor). I understand due that due to the non-differential architecture the common mode voltage would be a problem for high side sensing?

Do you think this part would be suitable for low side current sensing where Bipolar input AIN_xP gets the positive voltage value of current drop across the resistor of voltage of maximum 1V (3 x 0.3 ohm) and AIN_xGND gets the value of the sense resistor ground?

Thanks in advance.

over 1 year ago

0 Tom Hendrick over 1 year ago

TI__Guru**** 172846 points

Hi Steven,

You are correct on the high side issue using the ADS8578. From the low side, you would be fine as long as the sense resister 'ground' is at the same potential as the AGND pins of the ADS8578.

0 Steven Shenker over 1 year ago in reply to Tom Hendrick

Intellectual 850 points

Thanks for your quick reply Tom. If AGND is sometimes lifted to around 150mV for brief periods does the input protection rules apply for the AGND pin as well up to +-20V? IE this table:

0 Tom Hendrick over 1 year ago in reply to Steven Shenker

TI__Guru**** 172846 points

Hi Steven,

Are you asking about the AGND (i.e. power) pins or the AIN_nGND pins? From the operating standpoint, the AIN_nGND can swing +/-100mV from the AGND reference.

0 Steven Shenker over 1 year ago in reply to Tom Hendrick

Intellectual 850 points

Sorry I was referring to the AIN_nGND pins. I wanted to clarify whether the above table applies to them as well. From a reliability (not operational) standpoint whether they can also tolerate the +-20V range.

0 Tom Hendrick over 1 year ago in reply to Steven Shenker

TI__Guru**** 172846 points

Thank you for clarifying - the table applies there as well.

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ADS8678: Low side current sensing application suitability