ADS8867: Brown out results in unrecoverable all-zero output

David Bleloch

Part Number: ADS8867
Other Parts Discussed in Thread: ADS7066

Dear Sirs Mdms,

we are currently using the ADS8867 in a datalogging application, currently in production, and we have a significant number of returned units with the following issue.

The device is powered by a long life battery. When the battery nears end of life, we sometimes see a brownout event which is detected by our supervisory chip, which resets our processor. The ADC does not get a full power cycle but simply stops putting out any data after the event. Further investigation of RMA units shows that in this condition DOUT is "stuck at" 0. We don't have the functionality to power cycle the device with sufficient delay, and there is no reset on the converter.

Can the device be reset through the SPI lines, for instance by clocking a large number of edges into the device with the other SPI lines in a particular state?

Many thanks in advance.

David

over 5 years ago

0 Keith Nicholas over 5 years ago

TI__Mastermind 47650 points

Hello David,

The ADS88xx family does not have a brown-out circuit, and as far as I know, the only way to reset the device is to do a full power cycle.

I will do some digging to see if there are any other options, but I do not believe this is the case.

I will provide an update before end of business tomorrow.

Regards,
Keith Nicholas
Precision ADC Applications

0 David Bleloch over 5 years ago in reply to Keith Nicholas

Prodigy 80 points

Thanks Keith,

I appreciate that it's a long shot but it would get us out of a hole.

Kind regards

0 Keith Nicholas over 5 years ago in reply to David Bleloch

TI__Mastermind 47650 points

Hi David,

Unfortunately, there is no internal reset sequence or internal brown-out circuit. Once the brown-out condition occurs, the only way to recover the ADS8867 is to do a full power cycle by taking the supplies to 0V, and then ramping back up to the correct voltage levels.

Regards,
Keith

0 David Bleloch over 5 years ago in reply to Keith Nicholas

Prodigy 80 points

Hiya Keith

Oh well, many thanks for looking into this for me. We'll have to look for another way around the problem.

Have a great weekend,

David

0 Keith Nicholas over 5 years ago in reply to David Bleloch

TI__Mastermind 47650 points

Hi David,

We do have a new 16b device with brown-out, ADS7066, but I assume you need to find a solution with your existing design.

Have a nice weekend as well!

Regards,
Keith

Data converters

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ADS8867: Brown out results in unrecoverable all-zero output