L9803 STMicroelectronics, L9803 Datasheet - Page 29

• Manufacturer Part Number: L9803
• Description: Super Smart Power Motor Driver With 8-bit Mcu, Ram, Eeprom, Adc, Wdg, Timers, Pwm And H-bridge Driver
• Manufacturer: STMicroelectronics

L9803
3.7
3.7.1
3.7.2
Note:
3.7.3
Power Saving Modes
Introduction
There are three Power Saving modes. The Slow Mode may be selected by setting the
relevant bits in the Miscellaneous register as detailed in
may be entered using the WFI and HALT instructions.
Slow Mode
In Slow mode, the oscillator frequency can be divided by 4, 8, 16 or 32 rather than by 2. The
CPU and peripherals (except CAN, see Note) are clocked at this lower frequency. Slow
mode is used to reduce power consumption.
Before entering Slow mode and to guarantee low power operations, the CAN Controller
must be placed by software in STANDBY mode.
Wait Mode
Wait mode places the MCU in a low power consumption mode by stopping the CPU. All
peripherals remain active. During Wait mode, the I bit (CC Register) is cleared, so as to
enable all interrupts. All other registers and memory remain unchanged. The MCU will
remain in Wait mode until an Interrupt or Reset occurs, whereupon the Program Counter
branches to the starting address of the Interrupt or Reset Service Routine.
The MCU will remain in Wait mode until a Reset or an Interrupt (coming from CAN, Timers 1
& 2, EEPROM, ADC, PWM 1 & 2, I/O ports peripherals and Power Bridge) occurs, causing
its wake-up.
Refer to
Figure 13. Wait Mode Flow Chart
Figure 12
below.
N
INTERRUPT
Y
Clocks, Reset, Interrupts & Power saving modes
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
I-BIT
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
I-BIT
OR SERVICE INTERRUPT
FETCH RESET VECTOR
N
WAIT INSTRUCTION
RESET
Section
Y
ON
ON
ON
SET
ON
ON
OFF
CLEARED
3.4. Wait and Halt modes
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