printed circuit board (PCB) components in descending order of priority:
1. The switch-mode power supply (SMPS) components
2. Bluetooth® radio frequency (RF) trace and band-pass filter
3. Bluetooth RF decoupling
4. Crystal (XTAL)
5. Audio BGBYP capacitor
6. VDD_DIG decoupling
7. The quad serial peripheral interface (QSPI) flash devices and decoupling
8. All other decoupling
SMPS
1.8 V SMPS output
digital SMPS changes between 1.1 V and 0.85 V depending on the power mode of the integrated circuit
three modes PWM PFM ULP(PFM)
PWM frequency 2 MHz PWM max load current 350 mA 150 mA
PFM / ULP max load current 40 mA 55 mA