[sdiy] Driving SSI2144 freq control with PWM from a microcontroller

[Eric Brombaugh]

There's a way to mitigate that - ensure that you always have a high and 
low transition in every cycle. Basically you create a very high 
frequency PWM signal that's either 33% or 67% depending on the state of 
your PDM bit, so the speed of the high & low transitions are always part 
of your output and don't vary with the data value. Downside is that your 
PDM bitrate has to be 1/3 of that you'd get without doing this approach.

Eric

On 11/5/22 07:50, René Schmitz wrote:
> 
> One caveat with PDM at higher frequencies is that you need fast and 
> symmetric rise and fall times on the digital drivers. A little turn-on 
> or turn-off delay (and any imbalance) distorts your signal.