SAADC : "The SAMPLERATE timer mode cannot be combined with SCAN mode, and only one channel can be enabled in this mode. " Why ?

[MCB]

it says "The SAMPLERATE timer mode cannot be combined with SCAN mode, and only one channel can be
enabled in this mode." , simply why ? 

When we set scan mode , and when we call sample task , is adc using internal timer to scan each channel ? is this the reason that we can not use adc's internal timer with scan mode or more than one channel ?

[haakonsh]

"it says "The SAMPLERATE timer mode cannot be combined with SCAN mode, and only one channel can be
enabled in this mode.", simply why ? " 

I don't know, it's an HW limitation on a feature that is never used. We only exposed the functionality on the latest nRF5 SDK 16.0. I'm guessing it was a bug that never got high enough priority to be fixed. 

"When we set scan mode, and when we call sample task , is adc using internal timer to scan each channel ?"
No, an internal state-machine handles that.