HT46R068B/HT46R069B
Enhanced A/D Type 8-bit OTP MCU
Operating Modes
By using the LXT low frequency oscillator in combination with a high frequency oscillator, the
system can be selected to operate in a number of different modes. These Modes are Normal, Slow,
Idle and Sleep.
Mode Types and Selection
The higher frequency oscillators provide higher performance but carry with it the disadvantage of
higher power requirements, while the opposite is of course true for the lower frequency oscillators.
With the capability of dynamically switching between fast and slow oscillators, the device has
the flexibility to optimise the performance/power ratio, a feature especially important in power
sensitive portable applications.
For these devices the LXT oscillator can run together with any of the high speed oscillators,
namely the HXT, ERC or the HIRC. The CLKMOD bit in the CTRL0 register can be used to
switch the system clock from the selected high speed oscillator to the low speed LXT oscillator.
When the HALT instruction is executed the LXT oscillator can be chosen to run or not using the
LXTEN bit in the CTRL2 register.
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System Clock Configurations
For all devices, when the system enters the Sleep or Idle Mode, the high frequency system clock
will always stop running. The accompanying tables shows the relationship between the CLKMOD
bit, the HALT instruction and the high/low frequency oscillators. The CLMOD bit can change
normal or Slow Mode.
● Operating Mode Control
HALT
Instruction
CLKMOD LXTEN High Speed System Clock
Low Speed
System Clock LXT
Operating
Mode
bit
bit
XTAL/IRC/ERC
0
1
x
x
x
x
1
0
Rꢀn
Stop
Stop
Stop
On
On
On
Off
Noꢁmal
Slow
Idle
Not
execꢀted
Execꢀted
Sleep
Rev. 1.00
3ꢃ
�anꢀaꢁꢂ ꢃꢄꢅ ꢃ011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
