ADS112C04 : data rate What's wrong

Hi Kim Sungsoo,

Welcome to the E2E forum!  It would seem that there is considerable noise in your measurement.  When operating at the slower data rate the noise averages out.  The noise can come from a number of sources including the analog supply, poor grounding, noise from the input supplies, pickup of EMI/RFI in cabling as well as power line-cycle pickup in wiring.

For verification, try running in continuous conversion mode and take a series of measurement to see how much noise is affecting the returned result.

Also, can you give more detail:

• On your mux settings and how you are connecting the input voltages being measured? 
• How close to the input voltage is the measured result? 
• Do you have a schematic you can share? 
• And what does 'temp_AD' represent?  If this is the internal temp sensor, then you are changing the contents of Register 1.
• Have you verified that your communication is working correctly for register reads and writes?

Best regards,

Bob B

Thank you for quick response.

Vout1 = Configuration Register 0 (0X00)

    Configuration Register 1 (0X00)

Vout2 = Configuration Register 0 (0X60)

              Configuration Register 1 (0X00)

TEMP = Configuration Register 1 (0X01) (Temperature)

Vout1_Ad = d8a Vout1 = 0.216632 Vout2_ad = 3d83 Vout2 = 0.984217 temp_AD = c26b  temp = -6351
Vout1_Ad = d88 Vout1 = 0.216507 Vout2_ad = 3d8c Vout2 = 0.984780 temp_AD = c26c  temp = -6351

Vout1_Ad = d88 Vout1 = 0.216507 Vout2_ad = 3d8a Vout2 = 0.984655 temp_AD = c266  temp = -6352
Vout1_Ad = d87 Vout1 = 0.216444 Vout2_ad = 3d92 Vout2 = 0.985155 temp_AD = c26b  temp = -6351

Vout1 = Configuration Register 0 (0X00)

    Configuration Register 1 (0XA0)

Vout2 = Configuration Register 0 (0X60)

              Configuration Register 1 (0XA0)

TEMP = Configuration Register 1 (0XA1) (Temperature)

Vout1_Ad = 3dd7 Vout1 = 0.989468 Vout2_ad = c1b2 Vout2 = -0.996905 temp_AD = d94  temp = 271
Vout1_Ad = 3e63 Vout1 = 0.998218 Vout2_ad = c188 Vout2 = -0.999530 temp_AD = d92  temp = 271

Vout1_Ad = 3e78 Vout1 = 0.999530 Vout2_ad = c188 Vout2 = -0.999530 temp_AD = d90  temp = 271
Vout1_Ad = 3e56 Vout1 = 0.997405 Vout2_ad = c1c4 Vout2 = -0.995780 temp_AD = d8f   temp = 270

Voutx_AD * 0.0000625019 = Voutx

temp_AD >> 2 * 0.3125 = temp

Input voltage = 1v

The ads112c04 test takes place in the office.

Change only Configuration Register1 value

The input voltage is supplied by the power supply.

Isn't a lower data rate better for noise?

I would like to know why I need to speed up my data to get the right value.

Are there any problems with the work sequence below? (1 second per lead time)

VOUT1

The data value seems to be correct. This is a problem because the previous data values ​​come out.

Thank you.