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ADS112C04: external reference voltage [(VREFP – VREFN) / 4] selected as inputs to the ADC doesn't work

Pau Vilanova
Prodigy 10 points
Part Number: ADS112C04

Hello,

We are configuring the ADS112C04 to mesure its external reference voltage /4 (5V/4 = 1.25V) (MUX[3:0]=1100, gain bypassed=1)

Even though all the other self thests works, this one fails, giving us 0.5V. The Voltage between REFp and REFn is 5V.

Did we miss anything in the configuration? 

Configuration Register 0 = 0xC1 (CONFIG0_MUX_VREF_DIV4, CONFIG0_GAIN_1, CONFIG0_PGA_BYPASS_YES_DISABLED)

Configuration Register 1 = 0x78 (CONFIG1_DR_175_SPS, CONFIG1_MODE_TURBO, CONFIG1_CM_CONTINUOUS, CONFIG1_VREF_INT, CONFIG1_TS_DISABLED)

Configuration Register 2 = 0x20 (CONFIG2_DCNT_DISABLED, CONFIG2_CRC_CRC16, CONFIG2_BCS_DISABLED, CONFIG2_IDAC_OFF)

Configuration Register 3 = 0x00 (CONFIG3_I1MUX_DISABLED, CONFIG3_I2MUX_DISABLED)

Thanks

  • 0
    TI__Prodigy 320 points

    Hello Pau,

    My apologies for the delayed response.  I am working on your request and will get back to you in a day or two.

  • +1 in reply to Henry Sarmiento
    TI__Prodigy 320 points

    Hello Pau,

    Once again, I apologize for the delayed response.

    I used our ADS112C04EVM evaluation module to help answer your question.  Please, see below:

    • Tried the configuration register settings you listed and didn't get an output voltage of 0.5V like you did.  I got the device's internal 2.048V reference.
    • After looking further, found configuration registers' 0, 2, 3 settings that you listed in your question are good.
    • Your setting of Configuration Register 1 = 0x78 selects the Turbo operating mode at 350 SPS and selects the internal 2.048V reference source.
    • Due to your testing using external reference voltage pins REFP and REFN, set configuration register to 0x7A

    Results of using Configuration Register 0 = 0xC1, Configuration Register 1 = 0x7A, Configuration Register 2 = 0x20, Configuration Register 3 = 0x00:

    Best Regards,

    Henry Sarmiento

  • 0 in reply to Henry Sarmiento
    Prodigy 10 points

    Hello Henry,

    That change on the configuration Register 1 worked.

    Thanks!