HT45F3W datasheet(45/167 Pages) HOLTEK

45 / 167 page

Rev. 1.50

De�e��e� 01� �01�

Rev. 1.50

De�e��e� 01� �01�

HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

Oscillators

Variousoscillatoroptionsoffertheuserawiderangeoffunctionsaccordingtotheirvarious

applicationrequirements.Theflexiblefeaturesoftheoscillatorfunctionsensurethatthebest

optimisationcanbeachievedintermsofspeedandpowersaving.Oscillatorselectionsandoperation

areselectedthroughacombinationofconfigurationoptionsandregisters.

Oscillator Overview

Inadditiontobeingthesourceofthemainsystemclocktheoscillatorsalsoprovideclocksources

fortheWatchdogTimerandTimeBaseInterrupts.Externaloscillatorsrequiringsomeexternal

componentsaswellasfullyintegratedinternaloscillators,requiringnoexternalcomponents,

areprovidedtoformawiderangeofbothfastandslowsystemoscillators.Alloscillatoroptions

areselectedthroughtheconfigurationoptions.Thehigherfrequencyoscillatorsprovidehigher

performancebutcarrywithitthedisadvantageofhigherpowerrequirements,whiletheopposite

isofcoursetrueforthelowerfrequencyoscillators.Withthecapabilityofdynamicallyswitching

betweenfastandslowsystemclock,thedevicehastheflexibilitytooptimizetheperformance/

powerratio,afeatureespeciallyimportantinpowersensitiveportableapplications.

Type

Name

Freq.

Pins

Exte�nal C�ystal

HXT

400kHz~1�MHz

OSC1/OSC�

Exte�nal RC

ERC

4MHz~1�MHz

OSC1

Inte�nal High Speed RC

HIRC

8MHz

—

Exte�nal Low Speed C�ystal

LXT

3�.7�8kHz

XT1/XT�

Inte�nal Low Speed RC

LIRC

3�kHz

—

Oscillator Types

System Clock Configurations

Therearefivemethodsofgeneratingthesystemclock,threehighspeedoscillatorsandtwolow

speedoscillators.Thehighspeedoscillatorsaretheexternalcrystal/ceramicoscillator,externalRC

oscillatorandtheinternal8MHzRCoscillator.Thetwolowspeedoscillatorsaretheinternal32kHz

RCoscillatorandtheexternal32.768kHzcrystaloscillator.Selectingwhethertheloworhighspeed

oscillatorisusedasthesystemoscillatorisimplementedusingtheHLCLKbitandCKS2~CKS0

bitsintheSMOD0registerandasthesystemclockcanbedynamicallyselected.

Theactualsourceclockusedforeachofthehighspeedandlowspeedoscillatorsischosen

viaconfigurationoptions.Thefrequencyoftheslowspeedorhighspeedsystemclockisalso

determinedusingtheHLCLKbitandCKS2~CKS0bitsintheSMOD0register.Notethattwo

oscillatorselectionsmustbemadenamelyonehighspeedandonelowspeedsystemoscillators.Itis

notpossibletochooseano-oscillatorselectionforeitherthehighorlowspeedoscillator.

HT45F3W датащи(PDF) 45 Page - Holtek Semiconductor Inc

HT45F3W датащи(HTML) 45 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL