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ADS7953: Issues with ADC configuration and ADS7953 giving wrong data

Rahul Ramachandran
Intellectual 800 points

Part Number: ADS7953

My customer is facing a critical issue with ADC7953.

 

Sometimes after a power cycling the ADC gives wrong data. It appears that the device is not getting configured. And repeated configuration attempts doesn’t work.

This happens when the ADC has been running for quite some time and when the power is cycled.

Whenever the device is working correctly at power up, it continues to work well until power is cycled again.

 

This is happening on all our boards. We have tried several things to resolve this issue but haven’t been successful.

Request your help in resolving this.

 

We are using the device in Auto-1 mode with 2 x Range. We are reading 14 channels from the device.

 

SPI clock frequency : 2.6MHz

Configuration data:

0x4200

0x4001

0x8000

0xCFFF  /*Ch 12 and 13 not used*/

0x2C40

0x2841

 

Typical data when the device is working correctly.

0x02a8

0x12ab

0x22a9

0x348d

0x4493

0x5003

0x6732

0x7733

0x882d

0x9439

0xa003

0xb009

0xe000

0xf99c

 

When not working correctly:

0x0dcd

0x0dd0

0x0dd3

0x0dd3

0x0dd2

0x0dd3

0x0dd2

0x0dd2

0x0dd2

0x0dd1

0x0dcf

0x0dcf

0x0dcf

0x0dce

Could you please give pointers on how this could be solved?

  • 0
    TI__Mastermind 25070 points

    Hello,

    To make sure I understand correctly, the device can power up in a fault state where communication to it does nor work. The only way to get it out of this fault state, is another power cycle?

    I suspect that the power up sequence is not controlled and thus is not the same each time. The VA needs to always be greater or equal to VBD. Also, be sure that the digital communications bus is not active during power up. Can the customer observe the power supply lines and confirm that power up sequences is correct?

    Regards

    Cynthia