Rev. 1.40
46
March 29, 2019
Rev. 1.40
47
March 29, 2019
HT45F23A/HT45F24A
TinyPower
TM
Flash MCU with OPA & Comparators
HT45F23A/HT45F24A
TinyPower
TM
Flash MCU with OPA & Comparators
Operating Mode Switching and Wake-up
The devices can switch between operating modes dynamically allowing the user to select the best
performance/power ratio for the present task in hand. In this way microcontroller operations that
do not require high performance can be executed using slower clocks thus requiring less operating
current and prolonging battery life in portable applications.
In simple terms, Mode Switching between the NORMAL Mode and SLOW Mode is executed
using the HLCLK bit and CKS2~CKS0 bits in the SMOD register while Mode Switching from the
NORMAL/SLOW Modes to the SLEEP/IDLE Modes is executed via the a HALT instruction. When
a HALT instruction is executed, whether the devices enter the IDLE Mode or the SLEEP Mode is
determined by the condition of the IDLEN bit in the SMOD register and FSYSON in the WDTC
register.
When the HLCLK bit switches to a low level, which implies that clock source is switched from the
high speed clock source, f
H
, to the clock source, f
H
/2~f
H
/64 or f
L
. If the clock is from the f
L
, the high
speed clock source will stop running to conserve power. When this happens it must be noted that the
f
H
/16 and f
H
/64 internal clock sources will also stop running, which may affect the operation of other
internal functions such as the SIM. The accompanying flowchart shows what happens when the
devices move between the various operating modes.