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RMas
RMas
Associate II
December 22, 2022
Solved

STM32G474 Internal VS External DAC operation

Can anyone explain a usage case or purpose for the 4 Internal and 3 External DACs?

Can you operate all three external DACs simultaneously to provide 3 reference voltages?

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Peter BENSCH
Peter BENSCHBest answer
ST Technical Moderator
January 2, 2023

Yes, the DACs can work at the same time.

Section 22.5 lists the possibilities of operating the DACs in the various low-power modes. Here, the note "DAC used with DMA" means that the DACs can then only be updated with DMA, since the clock of the CPU is deactivated in these cases and the CPU can therefore not perform any updates of the DACs.

Regards

/Peter

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3 replies

Peter BENSCH
Peter BENSCH
ST Technical Moderator
December 22, 2022

External Unbuffered is a somewhat unfortunate designation.

There are 7 DACs built-in, 4 of which are unbuffered, i.e. without a post-amplifier, and 3 of which are equipped with a post-amplifier. A post-amplifier has the advantage of being able to drive a lower load impedance, but the disadvantages of having a somewhat limited output voltage range, as well as being slower.

More details about the DACs can be found in the data sheet and in the reference manual RM0440.

Does it answer your question?

Regards

/Peter

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RMas
RMasAuthor
Associate II
December 23, 2022

It sounds like the three buffered DACs can all operate at the same time? I only need to hold them at a voltage from 0-3V and adjust them every so often so speed should not be an issue. Section 22.5 shows that the DACs should also be able to operate in low power modes. Is there any consideration for the comment "DAC used with DMA"?

Peter BENSCH
Peter BENSCHBest answer
ST Technical Moderator
January 2, 2023

Yes, the DACs can work at the same time.

Section 22.5 lists the possibilities of operating the DACs in the various low-power modes. Here, the note "DAC used with DMA" means that the DACs can then only be updated with DMA, since the clock of the CPU is deactivated in these cases and the CPU can therefore not perform any updates of the DACs.

Regards

/Peter

In order 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.
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