OPAMP output: VDDA overconsumption

[Chris1]

Posted on May 22, 2017 at 15:35

The STM32L471 Errata document states that:  An overconsumption can appear on VDDA in the following conditions:

• a voltage VPAD is applied on PA3 or PB0 with VDDA+ 50 mV < VPAD < VDDA + 600 mV 

...

Our application uses PB0 as a GPIO output with a voltage in the range described above.  Is that matching the condition 'a voltage VPAD is applied'?

[Chris1]

Posted on May 23, 2017 at 16:23

Restating the question:

If our application results in voltage on PB0 but the voltage is supplied by the microcontroller, is that a case of 'a voltage VPAD is applied'?

Our application cannot tolerate an extra mA of current consumption.

[waclawek.jan]

Posted on May 24, 2017 at 00:12

I'm not ST so you might want to get confirmation through conservative channels, but I'd say yes.

JW

[waclawek.jan]

Posted on May 24, 2017 at 16:26

I wanted to suggest to (ab)use the comparator somehow as source of output, if it's only a plain GPIO output.

However, I read the ES and DS and RM last night but couldn't really decipher how to enable that output... Lucke me I don't need to use this chip :)

ST might want to comment.

JW

[Chris1]

Posted on May 24, 2017 at 16:14

Thanks, Jan.

I agree, likely only ST staff can clarify what their statement means.

[Amel NASRI · Accepted solution]

Posted on May 24, 2017 at 19:01

Hello Chris,

The VDDA overconsumption will occur if these conditions are valid:

• the voltage input on the used pin (PB0 in your case) is in the range VDDA + 50mV, VDDA + 600mV
• the temperature is below 0°C

As you are configuring your GPIO in output mode, you shouldn't be impacted by the limitation described in the errata sheet.

-Amel

[Chris1]

Posted on May 24, 2017 at 19:40

That's good news.

Thank you for the clarification.