Holtek HT66F0175 - Page 59

Rev. 1.50 58 August 28, 2017 Rev. 1.50 59 August 28, 2017
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
LVR
Internal Reset
t
RSTD
+ t
SST
Note:t
RSTD
ispower-ondelaywithtypicaltime=50ms
Low Voltage Reset Timing Chart
• LVRC Register
Bit 7 6 5 4 3 2 1 0
Name LVS7 LVS6 LVS5 LVS4 LVS3 LVS2 LVS1 LVS0
R/W R/W R/W R/W R/W R/W R/W R/W R/W
POR 0 1 0 1 0 1 0 1
Bit7~0 LVS7~LVS0:LVRvoltageselect
01010101:2.1V
00110011:2.55V
10011001:3.15V
10101010:3.8V
Othervalues:GeneratesaMCUreset–registerisresettoPORvalue
Whenanactuallowvoltageconditionoccurs,asspeciedbyoneofthefourdened
LVRvoltagevalueabove,anMCUresetwillgenerated.Theresetoperationwillbe
activatedafter2~3f
LIRC
clockcycles.Inthissituationtheregistercontentswillremain
thesameaftersucharesetoccurs.
Anyregistervalue,otherthanthefourdenedregistervaluesabove,willalsoresult
inthegenerationofanMCUreset.Theresetoperationwillbeactivatedafter2~3f
LIRC

clockcycles.However,inthissituationtheregistercontentswillberesettothePOR
value.
• CTRL Register
Bit 7 6 5 4 3 2 1 0
Name FSYSON — — — — LVRF LRF WRF
R/W R/W — — — — R/W R/W R/W
POR 0 — — — — x 0 0
“x”: unknown
Bit7 FSYSON:f
SYS
ControlinIDLEMode
Describedelsewhere.
Bit6~3 Unimplemented,readas“0”
Bit2 LVRF:LVRfunctionresetag
0:Notoccurred
1:Occurred
Thisbitissetto1whenaspeciclowvoltageresetconditionoccurs.Notethatthisbit
canonlybeclearedto0bytheapplicationprogram.
Bit1 LRF:LVRcontrolregistersoftwareresetag
0:Notoccurred
1:Occurred
Thisbitissetto1bytheLVRCcontrolregistercontainsanyundenedLVRvoltage
registervalues.Thisineffectactslikeasoftware-resetfunction.Notethatthisbitcan
onlybeclearedto0bytheapplicationprogram.
Bit0 WRF:WDTcontrolregistersoftwareresetag
Describedelsewhere.