Holtek HT66F002 - System Clocks; System Operation Modes; NORMAL Mode

Rev. 1.71 38 April 11, 2017 Rev. 1.71 39 April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HIRC
Prescaler
f
H
LIRC
Low Speed Oscillation
f
H
/2
f
H
/16
f
H
/64
f
H
/8
f
H
/4
f
H
/32
HLCLK
CKS2~CKS0 bits
f
SYS
f
LIRC
High Speed Oscillation
WDT
f
SYS
/4
f
TB
Time Base 0
Time Base 1
TBCK
f
L
f
TBC
IDLEN
System Clock Congurations
Note:Whenthesystemclocksourcef
SYS
isswitchedtof
L
fromf
H
,thehighspeedoscillationwill
stoptoconservethepower.Thusthereisnof
H
~f
H
/64forperipheralcircuittouse.
System Operation 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modesareusedwhenthemicrocontrollerCPUisswitchedoffto
conservepower.
Operating
Mode
Description
CPU f
SYS
f
LIRC
f
TBC
NORMAL mode On f
H
~f
H
/64 On On
SLOW mode On f
L
On On
IDLE0 mode Off Off On On
IDLE1 mode Off On On On
SLEEP0 mode Off Off Off Off
SLEEP1 mode Off Off On Off
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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rst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.