Clock configurations

PM0222

10/33

DocID025476 Rev 1

3.2.3

Disabling the 80 MHz RC oscillator

When the 80 MHz RC oscillator is not used by the CPU or by any peripheral for a long time,

it is recommended to power it down by setting CRMU.CCR0.ANA_PD80M to 1.

When powering down the 80 MHz RC oscillator, the software must change the CPU clock to

another source (32 kHz or external) first (CRMU.CCR0.HS_OSC_SEL = 0b01 for example),

and then execute a second CRMU register access to power down the oscillator

(CRMU.CCR0.ANA_PD80M = 1).

When powering up the 80 MHz RC oscillator, the software can power up the oscillator

(CRMU.CCR0.ANA_PD80M = 0) and change the CPU clock to the 80 MHz RC oscillator

source at the same time (CRMU.CCR0.HS_OSC_SEL = 0b00).