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The power supply of ADS8638

jacky lu
Intellectual 340 points
Other Parts Discussed in Thread: ADS8638

Hi:

I want to use ADS8638 in my design. In the datasheet, it only gives Specifications of HVDD=10V and HVSS=-10V. (also with a minimum/maximum specifications at HVDD=10V to 15V, HVSS=-10V to -15V).

I want to know, if it possible to supply HVDD=5V, HVSS=-5V? If yes, how will Range Select bits in Configuration Register will determine the input range??

Thanks

Regards

Jacky

  • 0
    TI__Expert 4405 points

    Jacky,

    Thank you for your query on the ADS8638.

    As specified in page 5 of the datasheet, using this device with HVDD=5V and HVSS=-5V is a valid as it within the spec range for each supply individually and it also satisfies the HVDD-HVSS > 10V condition.

    Assuming that the input signal is within the +/-5V range and that you are operating from the internal 2.5V reference, you will need to program the Range Select bits in the Configuration Register to ‘010’ to set the input range to +/-5V.

    Regards,

    Sandeep

  • 0 in reply to Sandeep Kasargod
    Intellectual 340 points

    Hi Sandeep:

    Thank you for your reply and instruction. I have a clear understanding about the input range of ADS8638.

    Looking at page 23 of the datasheet, I infer that ADS8638's input pin has the mechanism of over-voltage self-protection. But looking at page 2 of the datasheet, it specify the Absolute Maximum Ratings of AINn to AGND as [HVSS-0.3, HVDD+0.3]. Does the input pin AINn has the mechanism of over-voltage self-protection? Need I add the protection diode before AINn  pin?

    Thanks

    Regards

    Jacky

  • 0 in reply to jacky lu
    TI__Expert 4405 points

    Jacky,

    As shown on page 23 of the datasheet, the ADS8638 does have ESD diodes on each AIN pin to both HVDD and HVSS.

    It would be a good idea to include a series resistance on the AIN pins to limit the current in case of an ESD event.

    Regards,

    Sandeep

  • 0 in reply to Sandeep Kasargod
    Intellectual 340 points

    Sandeep:

    Thanks fro your replay and carful instruction. I have a clear understanding of this device.

    Regards

    Jacky