Hi!
What is the max PDM frequency I can set? Is the clock limited to these options?
https://docs.nordicsemi.com/bundle/ps_nrf5340/page/pdm.html
Reading the datasheet, there is huge SNR and power use difference from the clock speed. Is it possible to reach the low power mode (768khz) and high performance (3mhz) and even Ultrasonic mode(4.8mhz) on nrf54l15 and nrf54h20?
The short answer for the nRF5340: We have only tested and qualified specific listed values, hence we don't recommend other values (https://docs.nordicsemi.com/bundle/ps_nrf5340/page/pdm.html)
- 16 kHz output sample rate, 16-bit samples
- Selectable ratio of 64 or 80 between PDM_CLK and output sample rate
- 
For the nRF54L15 it looks to be more values supported, but you can assume the same: We have only tested and qualified specific listed values, hence we can't recommend other values (https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/pdm.html)
- 8 kHz, 16 kHz, 32 kHz, or 48k Hz output sample rate, 16-bit samples
- Supports digital microphone clocks at 768 kHz, 800 kHz, 1. 024 MHz , 1.536 MHz, 2.048 MHz , 3.072 MHz , 1.28 MHz, and 2.56 MHz
- Selectable ratio of 32, 48, 50, 64, 80, 96, 100, or 128 between PDM_CLK and output sample rate
Kenneth
