Holtek HT66F30 User Manual

Rev. 2.50 56 June 22, 2017 Rev. 2.50 57 June 22, 2017
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
Operating Modes and System Clocks
Presentdayapplicationsrequirethattheirmicrocontrollershavehighperformancebutoftenstill
demandthattheyconsumeaslittlepoweraspossible,conictingrequirementsthatareespecially
trueinbatterypoweredportableapplications.Thefastclocksrequiredforhighperformancewill
bytheirnatureincreasecurrentconsumptionandofcoursevice-versa,lowerspeedclocksreduce
currentconsumption.AsHoltekhasprovidedthesedeviceswithbothhighandlowspeedclock
sourcesandthemeanstoswitchbetweenthemdynamically,theusercanoptimisetheoperationof
theirmicrocontrollertoachievethebestperformance/powerratio.
System Clock
ThedevicehasmanydifferentclocksourcesforboththeCPUandperipheralfunctionoperation.
Byprovidingtheuserwithawiderangeofclockoptionsusingcongurationoptionsandregister
programming,aclocksystemcanbeconguredtoobtainmaximumapplicationperformance.
Themainsystemclock,cancomefromeitherahighfrequency,f
H
,orlowfrequency,f
L
,source,
andisselectedusingtheHLCLKbitandCKS2~CKS0bitsintheSMODregister.Thehigh
speedsystemclockcanbesourcedfromeitheranHXT,ERCorHIRCoscillator,selectedviaa
congurationoption.Thelowspeedsystemclocksourcecanbesourcedfrominternalclockf
L
.Iff
L

isselectedthenitcanbesourcedbyeithertheLXTorLIRCoscillators,selectedviaaconguration
option.Theotherchoice,whichisadividedversionofthehighspeedsystemoscillatorhasarange
off
H
/2~f
H
/64.
Therearetwoadditionalinternalclocksfortheperipheralcircuits,thesubstituteclock,f
SUB
,and
theTimeBaseclock,f
TBC
.EachoftheseinternalclocksaresourcedbyeithertheLXTorLIRC
oscillators,selectedviacongurationoptions.Thef
SUB
clockisusedtoprovideasubstituteclockfor
themicrocontrollerjustafterawake-uphasoccurredtoenablefasterwake-uptimes.
Togetherwithf
SYS
/4itisalsousedasoneoftheclocksourcesfortheWatchdogtimer.ThefTBC
clockisusedasasourcefortheTimeBaseinterruptfunctionsandfortheTMs.

Holtek HT66F30 Specifications

General

Brand	Holtek
Model	HT66F30
Category	Computer Hardware
Language	English