Holtek HT66F30 - Page 173

Rev. 2.50 172 June 22, 2017 Rev. 2.50 173 June 22, 2017
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
ADCR1 Register
Bit 7 6 5 4 3 2 1 0
Name ACS4
V125EN — VREFS — ADCK2 ADCK1 ADCK0
R/W R/W R/W — R/W — R/W R/W R/W
POR 0 0 — 0 — 0 0 0
Bit7 ACS4:SelecteInternal1.25VasADCinputControl
0:Disable
1:Enable
Thisbitenables1.25VtobeconnectedtotheA/Dconverter.TheV125ENbitmust
rsthavebeensettoenablethebandgapcircuit1.25VvoltagetobeusedbytheA/D
converter.WhentheACS4bitissethigh,thebandgap1.25Vvoltagewillberoutedto
theA/DconverterandtheotherA/Dinputchannelsdisconnected.
Bit6 V125EN:Internal1.25VControl
0:Disable
1:Enable
ThisbitcontrolstheinternalBandgapcircuiton/offfunctiontotheA/Dconverter.
Whenthebitissethighthebandgapvoltage1.25VcanbeusedbytheA/Dconverter.
If1.25VisnotusedbytheA/DconverterandtheLVR/LVDfunctionisdisabledthen
thebandgapreferencecircuitwillbeautomaticallyswitchedofftoconservepower.
When1.25VisswitchedonforusebytheA/Dconverter,atimet
BG
shouldbeallowed
forthebandgapcircuittostabilisebeforeimplementinganA/Dconversion.
Bit5 Unimplemented,readas“0”
Bit4 VREFS:SelecteADCreferencevoltage
0:InternalADCpower
1:VREFpin
ThisbitisusedtoselectthereferencevoltagefortheA/Dconverter.Ifthebitishigh,
thentheA/DconverterreferencevoltageissuppliedontheexternalVREFpin.Ifthepin
islow,thentheinternalreferenceisusedwhichistakenfromthepowersupplypinVDD.
Bit3 Unimplemented,readas“0”
Bit2~0 ADCK2, ADCK1, ADCK0:SelectADCclocksource
000:f
SYS
001:f
SYS
/2
010:f
SYS
/4
011:f
SYS
/8
100:f
SYS
/16
101:f
SYS
/32
110:f
SYS
/64
111:Undened
ThesethreebitsareusedtoselecttheclocksourcefortheA/Dconverter.