Why does STM32F4 DAC have left or right data alignment in 12-bit mode? What is that supposed to mean?

[Andrew C]

In the datasheet, it says that the DAC has left or right data alignment in 12-bit mode. What is this mode supposed to do? Also, it says "8-bit or 10-bit monotonic output". Does that mean in 12 bits, it is no longer monotonic?

[T J]

The top 8 bits are useful,

sometimes, its all you need,

hence the right justification...

to dump the bottom bits of noise....

[Tesla DeLorean]

It means it fills upper or lower bits depending on the user's application and needs.

If you want to do signed math you kind of want the data in the high order bits, or for example the interface they get sent over has different bit widths and discards low order bits. ie 12-bit data into a 10-bit codec.​