HT45F3820 Datasheet, PDF (34/121 Pages) Holtek Semiconductor Inc – Ultrasonic Atomizer Flash MCU

HT45F3820
Ultrasonic Atomizer Flash MCU
System Operating Modes
There are six different modes of operation for the microcontroller, each one with its own
special characteristics and which can be chosen according to the specific performance and
power requirements of the application. There are two modes allowing normal operation of the
microcontroller, the NORMAL Mode and SLOW Mode. The remaining four modes, the SLEEP0,
SLEEP1, IDLE0 and IDLE1 Mode are used when the microcontroller CPU is switched off to
conserve power.
Operating
Description
Mode
CPU
fSYS
fH
fSUB
NORMAL Mode
On
fH~fH/64
On
On
SLOW Mode
On
fSUB
Off
On
ILDE0 Mode
Off
Off
Off
On
IDLE1 Mode
Off
On
On/Off
On
SLEEP0 Mode ^(Note)
Off
Off
Off
Off
SLEEP1 Mode
Off
Off
Off
On
Note: If the Watchdog Timer configuration option is "Always enabled" which means the fSUB clock
must always be on, there is not SLEEP0 mode.
NORMAL Mode
As the name suggests this is one of the main operating modes where the microcontroller has all of
its functions operational and where the system clock is provided by the high speed oscillator. This
mode operates allowing the microcontroller to operate normally with a clock source will come from
the high speed oscillator, HIRC. The high speed oscillator will however first be divided by a ratio
ranging from 1 to 64, the actual ratio being selected by the CKS2~CKS0 and HLCLK bits in the
SMOD register. Although a high speed oscillator is used, running the microcontroller at a divided
clock ratio reduces the operating current.
SLOW Mode
This is also a mode where the microcontroller operates normally although now with a slower speed
clock source. The clock source used will be from fSUB. Running the microcontroller in this mode
allows it to run with much lower operating currents. In the SLOW Mode, the fH is off.
SLEEP0 Mode
If the WDT configuration option is "Always enabled", there is not SLEEP0 mode. If the WDT
configuration option is "controlled by WDTC register" the MCU can enter the SLEEP0 mode. The
SLEEP Mode is entered when an HALT instruction is executed and when the IDLEN bit in the
SMOD register is low. In the SLEEP0 mode the CPU will be stopped, and the fSUB and fS clocks
will be stopped too, and the Watchdog Timer function is disabled. In this mode, the LVDEN is must
cleared to zero. If the LVDEN is set high, it won’t enter the SLEEP0 Mode.
SLEEP1 Mode
The SLEEP Mode is entered when an HALT instruction is executed and when the IDLEN bit in
the SMOD register is low. In the SLEEP1 mode the CPU will be stopped. However the fSUB and fS
clocks will continue to operate if the LVDEN is "1" or the Watchdog Timer function is enabled.
IDLE0 Mode
The IDLE0 Mode is entered when a HALT instruction is executed and when the IDLEN bit in the
SMOD register is high and the FSYSON bit in the CTRL register is low. In the IDLE0 Mode the
system oscillator will be inhibited from driving the CPU, the system oscillator will be stopped, the
low frequency clock fSUB will be on to drive some peripheral functions.
Rev. 1.11
34
April 11, 2017