Hi, Hyunkee,
As the following figure, the default state of the pin is DAC1_OUT, CMP0_IN4 and ADC1_SE23, in other words, all three module output or input are connected togrther. When DAC is disabled, it's output is in in high impedance, so the pin is an input pin as CMP0_IN4 and ADC1_SE23.
Hope it can help you
BR
Xiangjun Rong
