STM32, DAC output buffer, maximum safe output current

[RAltm]

Hello,

I want to know the DAC output buffer maximum safe output current before damaging the output buffer. I know that it's not possible to get the output swing mentioned in the datasheet under this condition.
The datasheet maximum ratings doesn't state it for the DACs, and from the normal ratings only the current to keep the maximum output voltage around VREF+ can be calculated. So, either I wasn't able to locate the information in the datasheet (which is hopefully the case) or it isn't mentioned there at all.

I'm using a STM32U083 device, datasheet https://www.st.com/resource/en/datasheet/stm32u083kc.pdf

Regards

[MasterT]

Page 94-95 table.76 see "Resistive load", min. value R defines DAC's max. output current.

[RAltm]

Hello MasterT,

that's the value for normal operation. As I wrote, I want to know the value before damaging the output buffer.

Regards

[Ozone]

If you don't find this value in the DAC specific section or under "Absolute maximum ratings", you can safely assume it is not individually determined for DAC outs.

Perhaps ST staff can provide you more details.

[RAltm]

Hi Ozone,

no, I couldn't find the value specified anywhere. The value from your table is related to digital IO, I think. So, I think I've to clarify with ST staff as suggested by you.

Regards

[Michal Dudka]

In my opinion, the limit mentioned by Ozone generally applies to the DAC output. Furthermore, it is practically impossible to exceed this limit, because the DAC’s output buffer is not capable of supplying or sinking such high currents.

On the STM32G071, I shorted the zeroed DAC output against VCC (3.3V) and measured a current of approximately 1.7mA, and this had no effect on subsequent operation.

In my opinion, the minimum resistance value listed in the datasheet is not the limit beyond which damage occurs, but rather the minimum resistance at which it can be guaranteed that it will not affect the buffer’s function (it will not compromise accuracy).

[RAltm]

Hello Michal,

---

@Michal Dudka wrote:

On the STM32G071, I shorted the zeroed DAC output against VCC (3.3V) and measured a current of approximately 1.7mA, and this had no effect on subsequent operation.

---

Ah, that sounds good. Just knowing that the DAC can be shorted to GND/VCC without damaging the output buffer is enough information for me. 

Regards

[Ozone]

> The value from your table is related to digital IO, I think.

The text in the table says "any IO and control pin".

> So, I think I've to clarify with ST staff as suggested by you.

If that includes DAC output pins as I would surmise is a question that only ST staff can answer, yes.