ADS1248: ADS1248 read back FFFFFFFF

Hi huichun xing,

Do you see any activity on the DOUT pin under any circumstances? Or is the DOUT pin always high?

If the DOUT pin on the ADS1248 is always high, this could indicate that the device is not powered correctly, or the clock is not operating properly.

If you pull the START pin high, can you see pulses on the DRDY pin? This gives a good indication that the device is working correctly.

-Bryan

Bryan,

DOUT pin always high, no toggle;

Configured as Internal CLK, and SW RESET; 

When Start pin High, No pulse on DRDY pin. 

Thanks,

Hi huichun xing,

Please check that the power supplies are working correctly and that the correct voltage is being applied to the ADC pins. That is the only other obvious issue that could cause the ADC to not respond at all to the START pin

Do you have multiple devices that are having these same issues? Or is it just one ADS1248?

-Bryan

Bryan,

The power is the first condition we checked, Digital VDD 3.28V, Analog VDD 4.75V up to ADC pin, both normal.

Also we did have 3 good bds and 2 bad bds (RTD no data) for the rev build. First time we met this kind of issue. 

Even in debug mode, no response from beginning. 

Based on these, dos it look like a bad ADC part? 

I did check some previous rev , ADS1238 marking " ADS1248 12KG4 CHKC" and this rev marking "ADS1248 02KG4 CEG3".

Thanks,

Hi huichun xing,

Thanks for providing this additional information.

Can you please send me pictures of the topside markings on each device ("good" and "bad")?

Also, can you please let me know the name of your supplier for these devices?

-Bryan

To TI 0902.docx

Both in word file. We use third party PCBA vendor. These two bds are from different PCBA vendors. But I do not know their sourcing channel for the device. 

Hi huichun xing,

Thanks for sending this over. Let me look into this in more detail and get back to you. It will probably be Tuesday next week since there is a holiday on Monday

-Bryan

Bryan,

Thanks for the information. I found the issue in our engineering board. However we do have production bds in Pilot run from same vendor. Is there any way our sourcing quality can check the issue based on the marking? or any TI quality contact.

Thanks,