DAC output not reaching zero issue on STM32

[RezaNazari]

Dear STM32 Support Team,

I am facing a problem with the DAC module in one of your STM32 microcontrollers. Despite making sure that all the settings and configurations are correct, the DAC output never reaches zero volts, even when I provide a digital input value of 0 and enable the buffer, the output shows 48mV.

I am using a Nucleo board. However, despite these efforts, the DAC output remains slightly above zero. This behavior persists on several boards and chips, indicating that it may be a hardware limitation.

Please confirm whether this is the expected behavior of the DAC module or could there be a problem with the build or design with this particular microcontroller?(Or maybe it's because of the output protection diodes.) If additional software calibration or tuning is required, I would be very grateful for detailed guidance.

For reference, the microcontroller part number is [ STM32F446RET6 & STM32F405RGT6] and the development environment I am using is [Keil IDE].

Thank you for your support and I look forward to your response.

Best Regard,
REZA NAZARI
r.nazari8001@gmail.com

[TDK]

> I am facing a problem with the DAC module in one of your STM32 microcontrollers. Despite making sure that all the settings and configurations are correct, the DAC output never reaches zero volts, even when I provide a digital input value of 0 and enable the buffer, the output shows 48mV.

According to the datasheet, with the buffer on, the lower DAC output is guaranteed to go down to 0.2 V, but no lower.

If you need output down to 0 V, set the buffer off and use an external buffer chip.