HT66F4530 datasheet(67/224 Pages) HOLTEK

67 / 224 page

Rev. 1.00

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HT66F4530/HT66F4540/HT66F4550

A/D Flash MCU with Dual Operational Amplifiers

HT66F4530/HT66F4540/HT66F4550

A/D Flash MCU with Dual Operational Amplifiers

RES Pin Reset

AlthoughthemicrocontrollerhasaninternalRCresetfunction,iftheVDDpowersupplyrisetime

isnotfastenoughordoesnotstabilisequicklyatpower-on,theinternalresetfunctionmaybe

incapableofprovidingproperresetoperation.Forthisreasonitisrecommendedthatanexternal

RCnetworkisconnectedtotheRESpin,whoseadditionaltimedelaywillensurethattheRESpin

remainslowforanextendedperiodtoallowthepowersupplytostabilise.Duringthistimedelay,

normaloperationofthemicrocontrollerwillbeinhibited.AftertheRESlinereachesacertain

voltagevalue,theresetdelaytimetRSTDisinvokedtoprovideanextradelaytimeafterwhichthe

microcontrollerwillbeginnormaloperation.TheabbreviationSSTinthefiguresstandsforSystem

Start-upTimer.

FormostapplicationsaresistorconnectedbetweenVDDandtheRESpinandacapacitorconnected

betweenVSSandtheRESpinwillprovideasuitableexternalresetcircuit.Anywiringconnectedto

theRESpinshouldbekeptasshortaspossibletominimiseanystraynoiseinterference.

ForapplicationsthatoperatewithinanenvironmentwheremorenoiseispresenttheEnhancedReset

Circuitshownisrecommended.

VDD

RES

10kΩ~

100kΩ

0.01µF**

1N4148*

VSS

0.1µF~1µF

300Ω*

Note:*ItisrecommendedthatthiscomponentisaddedforaddedESDprotection.

**Itisrecommendedthatthiscomponentisaddedinenvironmentswherepowerlinenoiseis

significant.

External RES Circuit

MoreinformationregardingexternalresetcircuitsislocatedinApplicationNoteHA0075Eonthe

Holtekwebsite.

PullingtheRESPinlowusingexternalhardwarewillalsoexecuteadevicereset.Inthiscase,asin

thecaseofotherresets,theProgramCounterwillresettozeroandprogramexecutioninitiatedfrom

thispoint.

Inte�nal Reset

tRSTD+tSST

0.9VDD

0.4VDD

RES

RESReset Timing Chart

HT66F4530 Datasheet(PDF) 67 Page - Holtek Semiconductor Inc

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