ADS7056: ADS7056EVM issue

Sunny Qin

Part Number: ADS7056
Other Parts Discussed in Thread: OPA856, , OPA836

Hi Team,

My customer evaluating our ADS7056EVM now, and they found an strange issue, when they input a stable DC voltage on input of ADS7056EVM(input to OPA856 of EVM), then click continue capture data button on our GUI, they get data as below:

they found first 2000 data was higher than input volage, and it drop to right value slowly, sampling rate is 2.5MHz.

Customer use logic analysis equipment to capture SPI line of ADS7056, SPI data is the same with GUI, so we don`t know why this happened, do you have some comments?

Thanks very much.

Regards, Sunny

over 4 years ago

0 Cynthia over 4 years ago

TI__Mastermind 24940 points

Hello Sunny,

You can confirm that there has not been any editions to the board? In particular to the passive components on the input driver, OPA836?

Also, would you measure the input at the OPA836, and also at the ADC input pin. This confirm that the input is not still settling.

This has been confirmed with the GUI, correct?

Regards

Cynthia

0 Sunny Qin over 4 years ago in reply to Cynthia

TI__Expert 4890 points

Hi Cynthia,

1, no editions to the EVM.

2, we already measured ADC PIN and OPA836 PIN, the signal is stable.

3, we tried to input DC signal directly to ADC, result it same.

could you help to check if any issue happen on EVM?

Thanks.

Regards, Sunny

0 Cynthia over 4 years ago in reply to Sunny Qin

TI__Mastermind 24940 points

Sunny,

Once I get hardware onsite, I will try this on the EVM and let you know

Regards

Cynthia

0 Sunny Qin over 4 years ago in reply to Cynthia

TI__Expert 4890 points

Hi Cynthia,

ok, thanks for your help.

Regards, Sunny

0 Cynthia over 4 years ago in reply to Sunny Qin

TI__Mastermind 24940 points

Hi Sunny,

Many apologies for the very late response. With the end of the year, we get bombarded with many things.

But I finally was able to hope up the EVM and from the pictures below, you can see that if the input is stable and DC the ADC will not measure any zeros at the beginning. If the ADC is measuring an input that is rising and stabilizing, then you will see the rise from low to the input voltage.

Please let me know if you still have issues.

0 Sunny Qin over 4 years ago in reply to Cynthia

TI__Expert 4890 points

Hi Cynthia,

ok, many thanks for your help.

Regards, Sunny

Data converters

Data converters forum

ADS7056: ADS7056EVM issue