DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer? and if I need to drive with the DAC an external circuit, How can I solve the issue?

[Hicss.2033]

..

[Ozone]

> DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer?

Yes. Look closely in the datasheet.

> How can I solve the issue?

Disable the internal buffer amplifier.

Use a proper external amplifier, taking the high output impedance of the DAC into account.

[Hicss.2033]

And is there any way (a voltage level traslator or regulator) to shift this level to zero so that the overall output is zero? This is to generate waves starting from zero.

[Ozone]

Reading the datasheet will reveal ST specifies up to 200mV offset at the DAC output with buffer amplifier enabled.

Either accept that, or turn the internal buffer amplifier off, or use an external DAC.

[Hicss.2033]

I've turned the internal buffer amplier off, and I measure for 0 a value of about 2V (and not zero).

So it seems that disabling the buffer does not solve the trouble.....

[Hicss.2033]

and thank you for your fast answer.

[waclawek.jan]

> I've turned the internal buffer amplier off,

> and I measure for 0 a value of about 2V

What exactly is connected to the output amplifier?

JW

[Hicss.2033]

A digital multimeter
Inviato da Posta per Windows 10
Da: ST Community
Inviato: lunedì 29 giugno 2020 19:39
A: [e-mail]
Oggetto: waclawek.jan answered you: DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer? and if I need to drive with the DAC an external circuit, How can I solve the issue?
> I've turned the internal buffer amplier off, > and I measure for 0 a value of about 2V   What exactly is connected to the output amplifier?   JW
 
 
 
 
 
 
waclawek.jan (Community Member)
> I've turned the internal buffer amplier off,
> and I measure for 0 a value of about 2V
 
What exactly is connected to the output amplifier?
 
JW
 
  or reply to this email
 
 
 
 
 
 
Replying to
 
 
 
Hicss.2033 (Community Member) asked a question.
Thursday, October 17, 2019 12:35 AM
DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer? and if I need to drive with the DAC an external circuit, How can I solve the issue?
 
 
 
 
 
 
 
waclawek.jan (Community Member)
> I've turned the internal buffer amplier off,
> and I measure for 0 a value of about 2V
 
What exactly is connected to the output amplifier?
 
JW
Monday, June 29, 2020 10:39 AM
 
 
 
 
 
 
 
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[waclawek.jan]

>>> I've turned the internal buffer amplier off,

>>> and I measure for 0 a value of about 2V

>>

>>What exactly is connected to the output amplifier?

 >

> A digital multimeter.

Nothing else?

Which pin do you use?

Try the other DAC output.

Try other values into DAC.

JW

[Hicss.2033]

I’m using DAC channel 1 on PA4.
For FFF is OK, but for 1000 (decimal) I’ve 2.2v.
Anyway moving to channel 2 on PA5 I’ve 0 (and in buffered mode I have an out put for zero of .05V, that is better than the previous one).
Thanks for your help!!
Inviato da Posta per Windows 10
Da: ST Community
Inviato: martedì 30 giugno 2020 07:18
A: [e-mail]
Oggetto: waclawek.jan answered you: DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer? and if I need to drive with the DAC an external circuit, How can I solve the issue?
>>> I've turned the internal buffer amplier off, >>> and I measure for 0 a value of about 2V >> >>What exactly is connected to the output amplifier?  > > A digital multimeter.   Nothing else? Which pin do you use?   Try the other DAC output.   Try other values into DAC.   JW
 
 
 
 
 
 
waclawek.jan (Community Member)
>>> I've turned the internal buffer amplier off,
>>> and I measure for 0 a value of about 2V
>>
>>What exactly is connected to the output amplifier?
 >
> A digital multimeter.
 
Nothing else?
Which pin do you use?
 
Try the other DAC output.
 
Try other values into DAC.
 
JW
 
  or reply to this email
 
 
 
 
 
 
Replying to
 
 
 
Hicss.2033 (Community Member) asked a question.
Thursday, October 17, 2019 12:35 AM
DAC Output not zero on STM32F429I discovery (about 180mv). Can someone give an answer? and if I need to drive with the DAC an external circuit, How can I solve the issue?
 
 
 
 
 
 
 
waclawek.jan (Community Member)
>>> I've turned the internal buffer amplier off,
>>> and I measure for 0 a value of about 2V
>>
>>What exactly is connected to the output amplifier?
 >
> A digital multimeter.
 
Nothing else?
Which pin do you use?
 
Try the other DAC output.
 
Try other values into DAC.
 
JW
Edited Monday, June 29, 2020 10:18 PM
 
 
 
 
 
 
 
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