HT68F14 HOLTEK [Holtek Semiconductor Inc], HT68F14 Datasheet - Page 33

• Manufacturer Part Number: HT68F14
• Description: Enhanced I/O Flash Type MCU
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

HT68F13/HT68F14/HT68F15
Enhanced I/O Flash Type MCU
Note that if the Watchdog Timer is disabled, which means that the LIRC oscillator is off, then there will be no Fast
Wake-up function available when the device wakes-up from the SLEEP0 Mode.
Rev. 1.10
Oscillator
Bit 0
System
HIRC
LIRC
Fast Wake-up
HXT
ERC
FSTEN
To minimise power consumption the device can enter the SLEEP or IDLE0 Mode, where the system
clock source to the device will be stopped. However when the device is woken up again, it can take a
considerable time for the original system oscillator to restart, stabilise and allow normal operation to
resume. To ensure the device is up and running as fast as possible a Fast Wake-up function is provided,
which allows f
the original system oscillator has stabilised. As the clock source for the Fast Wake-up function is f
the Fast Wake-up function is only available in the SLEEP1 and IDLE0 modes. When the device is
woken up from the SLEEP0 mode, the Fast Wake-up function has no effect because the f
stopped. The Fast Wake-up enable/disable function is controlled using the FSTEN bit in the SMOD
register.
If the HXT oscillator is selected as the NORMAL Mode system clock and the Fast Wake-up function is
enabled, then it will take one to two t
The system will then initially run under the f
elapsed, at which point the HTO flag will switch high and the system will switch over to operating
from the HXT oscillator.
If the ERC or HIRC oscillators or LIRC oscillator is used as the system oscillator then it will take
15~16 clock cycles of the ERC or HIRC or 1~2 cycles of the LIRC to wake up the system from the
SLEEP or IDLE0 Mode. The Fast Wake-up bit, FSTEN will have no effect in these cases.
Bit
0
1
X
X
X
HLCLK: system clock selection
This bit is used to select if the f
When the bit is high the f
selected. When system clock switches from the f
automatically switched off to conserve power.
0: f
1: f
H
H
/2 ~ f
15~16 HIRC cycles
15~16 ERC cycles
1024 HXT cycles
1024 HXT cycles
(SLEEP0 Mode)
1~2 LIRC cycles
Wake-up Time
H
/64 or f
SUB
, namely the LIRC oscillator, to act as a temporary clock to first drive the system until
L
H
clock will be selected and if low the f
and then switches over to run with the HXT clock)
(System runs with f
H
Wake-Up Times
(SLEEP1 Mode)
Wake-up Time
clock or the f
SUB
clock cycles of the LIRC oscillator for the system to wake-up.
33
15~16 HIRC cycles
15~16 ERC cycles
1024 HXT cycles
SUB
1~2 LIRC cycles
H
1~2 f
/2 ~ f
SUB
clock source until 1024 HXT clock cycles have
H
clock to the f
SUB
H
/64 or fL clock is used as the system clock.
first for 1024 HXT cycles
cycles
Wake-up Time
(IDLE0 Mode)
H
L
/2 ~ f
clock, the f
H
/64 or f
H
clock will be
L
clock will be
1~2 HIRC cycles
1~2 LIRC cycles
1~2 HXT cycles
1~2 HXT cycles
1~2 ERC cycles
February 9, 2011
Wake-up Time
(IDLE1 Mode)
²X² : don¢t care
SUB
clock is
SUB
,