ADS8568: IHVDD current value when HVDD is supplied before AVDD

T.C

Part Number: ADS8568

Dear data converter experts,

From 11 Power Supply Recommendations in the ADS8568 datasheet

”However, when HVDD is supplied before AVDD, the internal electrostatic discharge (ESD) structure conducts, increasing the IHVDD beyond the specified value until AVDD is applied.”

Could you please tell me specifically how many mA it will be when +15V is supplied to HVDD?

I am concerned that the rated current of the DCDC supplying HVDD may be exceeded.

Best regards,

11 months ago

0 Ryan Andrews 11 months ago

TI__Guru 59876 points

Hello TC,

Thank you for your post.

We don't have this information readily available. Let me order a new EVM and we will check the supply current on HVDD when AVDD is off. Please allow us a few days to get back to you (if find an unmodified one in our lab, we can measure it sooner). Thanks!

Regards,

Ryan

0 T.C 11 months ago in reply to Ryan Andrews

Prodigy 40 points

Hello Ryan,

Thanks for the reply.

I am looking forward to the results of the actual measurement.

Also, I understand that HVDD increases the current through the ESD diode until AVDD supply,
This doesn't mean that the HVDD will supply the AVDD current instead, right?

Our HVDD DCDC still has an extra 90mA.

It is possible to think that the current will draw instead until AVDD supply, but if IHVDD will draw regardless of IAVDD rating, I will refer to the measurement results.

Regards,

T.C

0 Ryan Andrews 11 months ago in reply to T.C

TI__Guru 59876 points

Thanks, TC. I will update you in a few days once we have some data to share.

Regards,

Ryan

+1 Ryan Andrews 10 months ago in reply to Ryan Andrews

TI__Guru 59876 points

Hi T.C.,

Sorry for the delay. We were able to take some measurements and we consistently saw the I_HVDD current under 5 mA before AVDD was enabled. It should not present a problem if your DCDC can handle up to 90 mA.

Regards,

Ryan

0 T.C 10 months ago in reply to Ryan Andrews

Prodigy 40 points

Hello Ryan,

I understand that it is 5mA.

Thank you for your investigation.

Regards,

T.C

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ADS8568: IHVDD current value when HVDD is supplied before AVDD