DAC8750 Damaged - Smoked

Brian Cavanagh

Other Parts Discussed in Thread: DAC8750

Hi, I have DVDD at 3.3Vdc and AVDD at 24VDC to power the DAC8750.

I have different power rails in my design, 3.3, 5.0, 12VDC and 24VDC(main input power).

For testing other circuits(not the DAC8750) on the board I powered the 24VDC without the other voltage rails turned on. Note, 24VDC was however going to AVDD pin (DAC8750), there was no voltage at the DVDD pin at that time.

My testing included starting at 24VDC and lowering until about 8VDC.

With the 24 volts applied, everything was fine. When I went to about 6 to 8VDC a part smoked (turned out to be the DAC8750).

Can someone give me any thoughts on why that would happen? Does DVDD and AVDD need to be powered at the same time? Please note, I was not testing the DAC just other circuits. This was an unforeseen result.

Thanks, Brian

over 9 years ago

0 Eugenio Mejia over 9 years ago

TI__Genius 10615 points

Hi Brian,

Brian Cavanagh said:
My testing included starting at 24VDC and lowering until about 8VDC.

The DAC8750 specifies a minimum AVDD voltage of 10 V, but even so, we would not expect the part to break like this. I will have to run some tests and discuss with my team.

How were you stepping down the voltage? Was it live? Or did you shut off the supply and apply the lower voltages?

Brian Cavanagh said:
Does DVDD and AVDD need to be powered at the same time?

There is no required power supply sequencing although DVDD is recommended to be powered on first.

What is the load at the output of the DAC?

0 Brian Cavanagh over 9 years ago in reply to Eugenio Mejia

Intellectual 285 points

Hi Eugenio, first, thank you for responding so quickly. I greatly appreciate it.
I was lowering the power supply voltage manually on my power supply.
I didn't have a load at my DAC terminals on the board, just floating.

Thanks again, Brian

0 Brian Cavanagh over 9 years ago in reply to Brian Cavanagh

Intellectual 285 points

Would you like me to send my schematic some how? I'd like not to display it on the website. Thanks

0 Eugenio Mejia over 9 years ago in reply to Brian Cavanagh

TI__Genius 10615 points

Hi Brian,

Your schematic would also be a big help.

To share it privately I only need your permission to contact you to your E2E registered email and we can have a private exchange.

0 Brian Cavanagh over 9 years ago in reply to Eugenio Mejia

Intellectual 285 points

Hi Eugenio, it is ok to contact me at my E2E registered email address. Thank you, Brian

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DAC8750 Damaged - Smoked