Max current possibly sourced from a DAC pin?

[JLemi]

Hello.

I would like to know how much current a DAC pin is able to source.

The STM32G081 datasheet indicates "Output current sourced by any I/O and control pin = 15mA". Is this 15mA also an upper limit to a DAC sourcing pin?

The STM32G081 datasheet also indicates "I DDA(DAC), DAC consumption from V DDA, DAC output buffer ON, max = 670 uA".

Is the current upper limit of a DAC pin 15 mA or 670 uA ?

Many thanks !

[waclawek.jan · Accepted solution]

> Is this 15mA also an upper limit to a DAC sourcing pin?

No, that's the digital output current.

> DAC consumption from V DDA, DAC output buffer ON, max = 670 uA".

That's power consumption, not output "drive".

DAC output "drive" is given by the "Output Impedance" paramater in the DAC characteristics table, typ. 11.7kOhm with output buffer OFF, so say at 1.17V if you load it by 100uA, it's output voltage will be only half of what you'd expect.

When DAC buffer is ON, the "Resistive load" parameter applies, i.e. if you load the DAC by 5kOhm and more against VSSA (ground), the output voltage should not depart from what you'd set int DAC. However, note, that the output swing is limited with DAC ON, see parameter "Voltage on DAC_OUT output", it will be limited to +-200mV from the rails.

JW

[JLemi]

Many thanks Jan, this was very helpful. JL

[Paul1]

Careful: Not sure about your STM but some STM32 "Output Buffer" option can introduce inaccuracies if calibration procedure isn't done. Raw DAC output is very accurate, while DAC Output Buffer is much stronger but may be inaccurate. Read fine print in datasheet for your IC, or use an external OpAmp.

Paul