Holtek HT66F002 - LCD Bias Current Control; SCOMC

Rev. 1.71 120 April 11, 2017 Rev. 1.71 121 April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
LCD Bias Current Control
TheLCDCOMdriverenablesarangeofselectionstobeprovidedtosuittherequirementofthe
LCDpanelwhicharebeingused.ThebiasresistorchoiceisimplementedusingtheISEL1and
ISEL0bitsintheSCOMCregister.
SCOMC
Bit 7 6 5 4 3 2 1 0
Name — ISEL1 ISEL0 SCOMEN COM3EN COM2EN COM1EN COM0EN
R/W — R/W R/W R/W R/W R/W R/W R/W
POR — 0 0 0 0 0 0 0
Bit7 Unimplemented,readas“0”
Bit6~5 ISEL1~ISEL0:SelectresistorforRtypeLCDbiascurrent(V
DD
=5V)
00:2×100kΩ(1/2Bias),I
BIAS
=25μA
01:2×50kΩ(1/2Bias),I
BIAS
=50μA
10:2×25kΩ(1/2Bias),I
BIAS
=100μA
11:2×12.5kΩ(1/2Bias),I
BIAS
=200μA
Bit4 SCOMEN:LCDcontrolbit
0:Disable
1:Enable
WhenSCOMENisset,itwillturnontheDCpathofresistortogenerate1/2V
DD
biasvoltage.
Bit3 COM3EN:PB3/AN7orSCOM3selection
0:PB3/AN7
1:SCOM3
Bit2 COM2EN:PB4/CLOorSCOM2selection
0:PB4/CLO
1:SCOM2
Bit1 COM1EN:PC1orSCOM1selection
0:PC1
1:SCOM1
Bit0 COM0EN:PC0orSCOM0selection
0:PC0
1:SCOM0