ADS5296A: ADS 5296 - test dc value

Zeev Gerber

Intellectual 290 points

Part Number: ADS5296A

Hi,

After deep dive investigation I found strange phenomena on the ADS5296A.

We test dc value in few values on all channel with 100 samples and check Repetitiveness.

We except delta for 0-2 bit (one bit = 2mv).

We have card with few channels which fail the test.

The failure in the test depend on the input dc values.

There are values that all channels pass the test.

The failed channel has two results:

good result which change with small DC addition
bad result which didn't change with small DC addition. (stay fix)

in same point of changing the dc input values, the bad result disappear and could start again with different dc value.

bad result could be different between channels.

I never see phenomena like this.

Pls. advise

9 days ago

0 Zeev Gerber 9 days ago

Intellectual 290 points

The test result point to missing codes of the ADC in the problematic channel.

right?

0 Sheetal Gupta 8 days ago

TI__Intellectual 1410 points

Hi Zeev,

Can you please share your observation data or screenshot of the failure trend you are observing on the below email ultrasound_rx-support@list.ti.com. We will assist you there. Also, does it look like INL break?

0 Zeev Gerber 8 days ago in reply to Sheetal Gupta

Intellectual 290 points

0 Zeev Gerber 8 days ago in reply to Zeev Gerber

Intellectual 290 points

see the test result we run on all channels 20 time per channel.

10%-20% from the sample have problem in the problematic channels.

when we have failure the sample LSB is A for specific channels or C for other specific channels

0 Sheetal Gupta 7 days ago in reply to Zeev Gerber

TI__Intellectual 1410 points

Hi Zeev,

Can you answer the following questions to help us understand the issue better.

1. Are you programming the device in 10-bit mode or 12-bit mode?

2. Does the delta shown in the image shared has units of bit? For example, delta = 10 means error of 10bits?

3. You mentioned that 1 bit = 2mV, how is that? For the ADC, one bit or 1 LSB would be 2Vpp/2^12 = 0.5mV. Are you using some other scheme to define the missing code error?

4. Can you specify the DC voltage sweep range in which you observed these missing codes?

5. The delta scheme is a little confusing, can you specify the missing code error in terms of DNL or INL as to how many LSBs missing code is observed?

6. Are you using a DAC to give this DC input voltage. Can you check the DNL/INL specification of this DAC also.

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ADS5296A: ADS 5296 - test dc value