ADS8586S: Measurement Error

senthil raj

Part Number: ADS8586S

We are experiencing linear scale error using ADS8586S and hence tested the ADC by feeding the external voltage reference to the ADC. We measure 2.65V instead of expected 2.5V.

The circuit used for testing is shown below. Any inputs on resolving the issue will help.

Thanks.

over 7 years ago

0 Dale Li over 7 years ago

TI__Mastermind 45725 points

Hello senthil,
Welcome to E2E forum.
Can you please use other precision voltage signal generator or other voltage reference as the input signal? a RC filter is highly recommended to use on ADC's input, please refer to Figure 54 or 84 in ADS8586S datasheet. A timing screenshot for the serial interface by a scope and conversion data file will be very helpful, thanks.

Best regards
Dale

0 Dale Li over 6 years ago in reply to Dale Li

TI__Mastermind 45725 points

Hi,
I didn't get response until 9/26, so close this thread. You can open another query if still have questions. Thanks.
Regards
Dale

0 senthil raj over 6 years ago in reply to Dale Li

Prodigy 60 points

Hi,

Sorry for the delayed response. We were currently developing a new prototype and hence the delay in response.

We used the following circuit to check and are facing the same issue. For the measurement using voltage referencenot sure how adding any filter on the input will help.

Please suggest thanks.

0 Dale Li over 6 years ago in reply to senthil raj

TI__Mastermind 45725 points

Hi senthil,
Can you please check if the voltage on REFIO(pin 42) is 2.5V? also can you please check the input signal on AIN1_P(pin 49) with a oscilloscope? this will check if AIN1_P is exactly 2.5V and no potential oscillation. A precision voltage signal generator is the best equipment to check. Do your AVCC come from a DC-DC or LDO? Is your MCU/CPU 5V level digital interface? Thanks.

Best regards
Dale

0 senthil raj over 6 years ago in reply to Dale Li

Prodigy 60 points

Hi Dale,

The first things to check are ref voltage input (pin 42) & the input voltage (pin 49) both are 2.5V. AVCC is from a dc-dc converter and the digital interface is 5V.

Thanks.

0 Dale Li over 6 years ago in reply to senthil raj

TI__Mastermind 45725 points

Hi Senthil,

Thanks to confirm reference voltage. Can you please check the input signal on AIN1_P(pin 49) with a oscilloscope? this will check if AIN1_P is exactly 2.5V and no potential oscillation. A precision voltage signal generator will be better to check as an DC input.

Thanks&regards

Dale

0 Dale Li over 6 years ago in reply to Dale Li

TI__Mastermind 45725 points

Hi Senthil,
Can you please let me know if you have new update or test result? thanks.

Best regards
Dale

0 senthil raj over 6 years ago in reply to Dale Li

Prodigy 60 points

Hi Dale,

The results are the same. We are currently assembling a new test board to rule out defects from the PCB. Will share the results once we test on the new PCB.

Thanks.

0 Dale Li over 6 years ago in reply to senthil raj

TI__Mastermind 45725 points

Hi Senthil,
Thank you to let me know about the latest status.

Best regards
Dale

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ADS8586S: Measurement Error