HT66F20 datasheet(73/298 Pages) HOLTEK

73 / 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

Whentheresetpinisdrivenlowbyexternalhardware,mostofthemicrocontrollerpinswillbe

forcedintoahighimpedancecondition.HoweverspecialattentionmustbemadetothePA5/C1X/

SDO/AN5andPB2/OSC2pinsasthesetwopinswillbeforcedintoalogicaloutputlowcondition

whentheresetpinisheldlow.Forthisreasonitisrecommendedthatthesetwopinsarenot

connectedtolowimpedancesourcesintheapplicationcircuittoeliminatethepossibilityoftwolow

impedancesourcesbeingconnectedtogether.Thissituationonlyoccurswhentheresetpinispulled

lowbyexternalhardwareandnotduringapoweronorotherresettype.

Pin Name

Pin Status

PA5/C1X/SDO/AN5

O�tp�t Low

PB�/OSC�

O�tp�t Low

Othe� pins

High Impedance

• LowVoltageReset–LVR

Themicrocontrollercontainsalowvoltageresetcircuitinordertomonitorthesupplyvoltage

ofthedevice,whichisselectedviaaconfigurationoption.Ifthesupplyvoltageofthedevice

dropstowithinarangeof0.9V~VLVRsuchasmightoccurwhenchangingthebattery,theLVR

willautomaticallyresetthedeviceinternally.TheLVRincludesthefollowingspecifications:

ForavalidLVRsignal,alowvoltage,i.e.,avoltageintherangebetween0.9V~VLVRmustexist

forgreaterthanthevaluetLVRspecifiedintheA.C.characteristics.Ifthelowvoltagestatedoes

notexceedtLVR,theLVRwillignoreitandwillnotperformaresetfunction.Oneofarangeof

specifiedvoltagevaluesforVLVRcanbeselectedusingconfigurationoptions.

LV R

In te r nal R es et

t RS TD + t SST

Note:tRSTDispower-ondelay,typicaltime=100ms

Low Voltage Reset Timing Chart

• WatchdogTime-outResetduringNormalOperation

TheWatchdogtime-outResetduringnormaloperationisthesameasahardwareRESpinreset

exceptthattheWatchdogtime-outflagTOwillbesetto“1”.

t RS TD + t SST

WD T Ti me - out

In te r nal R es et

Note:tRSTDispower-ondelay,typicaltime=100ms

WDT Time-out Reset during Normal Operation Timing Chart

• WatchdogTime-outResetduringSLEEPorIDLEMode

TheWatchdogtime-outResetduringSLEEPorIDLEModeisalittledifferentfromotherkinds

ofreset.MostoftheconditionsremainunchangedexceptthattheProgramCounterandtheStack

Pointerwillbeclearedto"0"andtheTOflagwillbesetto"1".RefertotheA.C.Characteristics

fortSSTdetails.

t SST

WD T Ti me - out

In te r nal R es et

Note:ThetSSTis15~16clockcyclesifthesystemclocksourceisprovidedbyERCorHIRC.

ThetSSTis1024clockforHXTorLXT.ThetSSTis1~2clockforLIRC.

WDT Time-out Reset during SLEEP or IDLE Timing Chart

HT66F20 Datasheet(PDF) 73 Page - Holtek Semiconductor Inc

HT66F20 Datasheet(HTML) 73 Page - Holtek Semiconductor Inc

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