HT45F65 datasheet(47/231 Pages) HOLTEK

47 / 231 page

Rev. 1.60

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Rev. 1.60

�7

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HT45F65/HT45F66/HT45F67

Glucose Meter 8-Bit Flash MCU

SomeconfigurationoptionsdetermineiftheXT1/XT2pinsareusedfortheLXToscillatororasI/Opins.

• IftheLXToscillatorisnotusedforanyclocksource,theXT1/XT2pinscanbeusedasnormalI/Opins.

• IftheLXToscillatorisusedforanyclocksource,the32.768kHzcrystalshouldbeconnectedto

theXT1/XT2pins.

Foroscillatorstabilityandtominimisetheeffectsofnoiseandcrosstalk,itisimportanttoensure

thatthecrystalandanyassociatedresistorsandcapacitorsalongwithinterconnectinglinesareall

locatedasclosetotheMCUaspossible.

To i nt er nal

ci rc ui ts

In te r nal

O sc ill at or

Ci rc ui t

No te :1 . Rp , C1 and C 2 ar e re qui r ed.

2. A lt hough not s how n pi ns h av e a

par as it ic c apac it an ce o f a r ound 7pF .

32. 7 68k Hz

In te r nal R C

O sc illa to r

External LXT Oscillator

LXT Oscillator C1 and C2 Values

Crystal Frequency

3�.768kHz

10pF

�ote: 1. C1 and C� values a�e fo� guidance only.

�. RP=5M~10MΩ is recommended.

32.768kHz Crystal Recommended Capacitor Values

LXT Oscillator Low Power Function

TheLXToscillatorcanfunctioninoneoftwomodes,theQuickStartModeandtheLowPower

Mode.ThemodeselectionisexecutedusingtheLXTLPbitintheTBCregister.

LXTLP Bit

LXT Mode

Quick Sta�t

Low-powe�

Afterpoweron,theLXTLPbitwillbeautomaticallyclearedtozeroensuringthattheLXToscillator

isintheQuickStartoperatingmode.IntheQuickStartModetheLXToscillatorwillpowerup

andstabilisequickly.However,aftertheLXToscillatorhasfullypoweredupitcanbeplaced

intotheLow-powermodebysettingtheLXTLPbithigh.Theoscillatorwillcontinuetorunbut

withreducedcurrentconsumption,asthehighercurrentconsumptionisonlyrequiredduringthe

LXToscillatorstart-up.Inpowersensitiveapplications,suchasbatteryapplications,wherepower

consumptionmustbekepttoaminimum,itisthereforerecommendedthattheapplicationprogram

setstheLXTLPbithighabout2secondsafterpower-on.

Itshouldbenotedthat,nomatterwhatconditiontheLXTLPbitissetto,theLXToscillatorwill

alwaysfunctionnormally,theonlydifferenceisthatitwilltakemoretimetostartupifintheLow-

powermode.

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