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OPAMP output: VDDA overconsumption

Chris1
Senior III
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'?

1 ACCEPTED SOLUTION

Accepted Solutions
Amel NASRI
ST Employee
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

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

6 REPLIES 6
Chris1
Senior III
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.

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

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

Posted on May 24, 2017 at 16:14

Thanks, Jan.

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

Amel NASRI
ST Employee
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

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Posted on May 24, 2017 at 19:40

That's good news.

Thank you for the clarification.