Datasheet

Product overview STM8AF52/62xx, STM8AF51/61xx
20/110 Doc ID 14395 Rev 9
5.6 Low-power operating modes
For efficient power management, the application can be put in one of four different low-
power modes. You can configure each mode to obtain the best compromise between lowest
power consumption, fastest start-up time and available wakeup sources.
● Wait mode
In this mode, the CPU is stopped but peripherals are kept running. The wakeup is
performed by an internal or external interrupt or reset.
● Active-halt mode with regulator on
In this mode, the CPU and peripheral clocks are stopped. An internal wakeup is
generated at programmable intervals by the auto wake up unit (AWU). The main
voltage regulator is kept powered on, so current consumption is higher than in Active-
halt mode with regulator off, but the wakeup time is faster. Wakeup is triggered by the
internal AWU interrupt, external interrupt or reset.
● Active-halt mode with regulator off
This mode is the same as Active-halt with regulator on, except that the main voltage
regulator is powered off, so the wake up time is slower.
● Halt mode
CPU and peripheral clocks are stopped, the main voltage regulator is powered off.
Wakeup is triggered by external event or reset.
In all modes the CPU and peripherals remain permanently powered on, the system clock is
applied only to selected modules. The RAM content is preserved and the brown-out reset
circuit remains activated.
Table 7. Peripheral clock gating bits (CLK_PCKENR2)
Control bit Peripheral
PCKEN27 CAN
PCKEN26 Reserved
PCKEN25 Reserved
PCKEN24 Reserved
PCKEN23 ADC
PCKEN22 AWU
PCKEN21 Reserved
PCKEN20 Reserved