ESP32S2 DAC No sinking output below 1.5V

[virtex]

Hi there,

I have here an ESP32S2-MINI-1U where I try to activate the DAC. According to the documentation it should work with the following two lines:
[Codebox]
dac_output_enable(DAC_CHANNEL_1);
dac_output_voltage(DAC_CHANNEL_1, Value);
[/Codebox]

Unfortunately, I cannot detect a voltage change on either channel 1 or 2. It's always around 1.5V (always tried to set a value near 0V).

Is it necessary to execute something more to be able to use the DAC?

Edit: I've used the cosine wave generator to generate a sin wave.

The behavior of the output then is strange. The sine wave does not fall below about 1.5V. So it is like a half rectified sine wave with a DC offset of 1.5V.
If I set the dc offset parameter of the structure dac_cw_config_t to a higher value, the sine wave is completely there.

I can reproduce this behavior with both DAC outputs. Currently both outputs have 10k ohm resistors connected to VCC.

Edit2:

It looks like this is normal behavior. According to the following topic viewtopic.php?t=5098, the integrated DAC is very bad as a current sink once the level drops below about 1.5V.

Can you please include this in the documentation for the DAC? That means it can only be operated with buffer as sink.