HT66F20 datasheet(72/298 Pages) HOLTEK

72 / 298 page

Rev. 1.90

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Rev. 1.90

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HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

Enhanced A/D Flash Type 8-Bit MCU with EEPROM

HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

Enhanced A/D Flash Type 8-Bit MCU with EEPROM

• RESPin

AstheresetpinissharedwithPB.0,theresetfunctionmustbeselectedusingaconfiguration

option.AlthoughthemicrocontrollerhasaninternalRCresetfunction,iftheVDDpowersupply

risetimeisnotfastenoughordoesnotstabilisequicklyatpower-on,theinternalresetfunction

maybeincapableofprovidingproperresetoperation.Forthisreasonitisrecommendedthatan

externalRCnetworkisconnectedtotheRESpin,whoseadditionaltimedelaywillensurethatthe

RESpinremainslowforanextendedperiodtoallowthepowersupplytostabilise.Duringthis

timedelay,normaloperationofthemicrocontrollerwillbeinhibited.AftertheRESlinereaches

acertainvoltagevalue,theresetdelaytimetRSTDisinvokedtoprovideanextradelaytimeafter

whichthemicrocontrollerwillbeginnormaloperation.TheabbreviationSSTinthefigures

standsforSystemStart-upTimer.

FormostapplicationsaresistorconnectedbetweenVDDandtheRESpinandacapacitor

connectedbetweenVSSandtheRESpinwillprovideasuitableexternalresetcircuit.Any

wiringconnectedtotheRESpinshouldbekeptasshortaspossibletominimiseanystraynoise

interference.

ForapplicationsthatoperatewithinanenvironmentwheremorenoiseispresenttheEnhanced

ResetCircuitshownisrecommended.

PB 0/ RE S

0. 1~ 1 m F

10k W ~

100k W

VD D

VS S

0. 01 m F* *

V DD

1N 4148*

300 W *

Note:*ItisrecommendedthatthiscomponentisaddedforaddedESDprotection.

**Itisrecommendedthatthiscomponentisaddedinenvironmentswherepower

linenoiseissignificant.

Extern RES Circuit

MoreinformationregardingexternalresetcircuitsislocatedinApplicationNoteHA0075Eon

theHoltekwebsite.

PullingtheRESPinlowusingexternalhardwarewillalsoexecuteadevicereset.Inthiscase,as

inthecaseofotherresets,theProgramCounterwillresettozeroandprogramexecutioninitiated

fromthispoint.

RE S

In te r nal R es et

0. 9 V DD

0. 4 V DD

t RS TD + t SST

Note: tRSTDispower-ondelay,typicaltime=100ms

RES Reset Timing Chart

HT66F20 Datasheet(PDF) 72 Page - Holtek Semiconductor Inc

HT66F20 Datasheet(HTML) 72 Page - Holtek Semiconductor Inc

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