ADC128D818: 12bits output data format of "16bits I2C output data", it is the high 12bits (bit[15]..bit[5]) or low 12bits (bit[11]..bit[0]) ?

Iven Xu

Intellectual 2090 points

Part Number: ADC128D818

Dear AE/SE team,

We are using ADC128D818 and we found the output data read from the registers are always 0? We have checked the I2C timing sequency that it is correct through check write/read the registers in the ADC128D818. Now I am suspect the below question?

Q: 12bits output data format of "16bits I2C output data", it is the high 12bits (bit[15]..bit[5]) or low 12bits (bit[11]..bit[0]) ?

customer is using low 12bits now.

Best Regards

Iven Xu

over 7 years ago

0 Joseph Wu over 7 years ago

TI__Guru* 97415 points

Iven,

The output data of the ADC128D818 is formatted so that data comes out filling up the 12 MSb, with 0000b for the last bits of a two byte register. You can find more information at the following E2E post:

e2e.ti.com/.../1634699

Joseph Wu

0 Iven Xu over 7 years ago in reply to Joseph Wu

TI__Intellectual 2090 points

Joseph,

Thanks for your confirmation. yes, it works after change to the 12bit MSB.

another question:
In page 33: Quick start, 9.2.2.2.1 => wait time, how much time for this "wait time"?

Could you please help comments for if keep the Not ready bit =1, how much time need to set in the software "maybe time out"? thanks.

Best Regards

Iven Xu

0 Tom Hendrick over 7 years ago in reply to Iven Xu

TI__Guru**** 180741 points

Hi Iven,

The I2C timeout should be 35mS MAX. Section 9.2.2.2.1 is referring to the power on reset functionality of the device which will be dependent to some extent of the ramp of the power supply as well as the amount of capacitance on the bus.

0 Iven Xu over 7 years ago in reply to Tom Hendrick

TI__Intellectual 2090 points

Thanks Tom.

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ADC128D818: 12bits output data format of "16bits I2C output data", it is the high 12bits (bit[15]..bit[5]) or low 12bits (bit[11]..bit[0]) ?