Holtek HT66F0175 - Low Voltage Detector - LVD

Rev. 1.50 170 August 28, 2017 Rev. 1.50 171 August 28, 2017
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
Low Voltage Detector – LVD
EachdevicehasaLowVoltageDetectorfunction,alsoknownasLVD.Thisenabledthedeviceto
monitorthepowersupplyvoltage,V
DD
,andprovideawarningsignalshoulditfallbelowacertain
level.Thisfunctionmaybeespeciallyusefulinbatteryapplicationswherethesupplyvoltagewill
graduallyreduceasthebatteryages,asitallowsanearlywarningbatterylowsignaltobegenerated.
TheLowVoltageDetectoralsohasthecapabilityofgeneratinganinterruptsignal.
LVD Register
TheLowVoltageDetectorfunctioniscontrolledusingasingleregisterwiththenameLVDC.Three
bitsinthisregister,VLVD2~VLVD0,areusedtoselectoneofeightxedvoltagesbelowwhich
alowvoltageconditionwillbedetermined.AlowvoltageconditionisindicatedwhentheLVDO
bitisset.IftheLVDObitislow,thisindicatesthattheV
DD
voltageisabovethepresetlowvoltage
value.TheLVDENbitisusedtocontroltheoverallon/offfunctionofthelowvoltagedetector.
Settingthebithighwillenablethelowvoltagedetector.Clearingthebittozerowillswitchoffthe
internallowvoltagedetectorcircuits.Asthelowvoltagedetectorwillconsumeacertainamountof
power,itmaybedesirabletoswitchoffthecircuitwhennotinuse,animportantconsiderationin
powersensitivebatterypoweredapplications.
LVDC Register
Bit 7 6 5 4 3 2 1 0
Name — — LVDO LVDEN — VLVD2 VLVD1 VLVD0
R/W — — R R/W — R/W R/W R/W
POR — — 0 0 — 0 0 0
Bit7~6 Unimplemented,readas“0”
Bit5 LVDO:LVDoutputag
0:NoLowVoltageDetected
1:LowVoltageDetected
Bit4 LVDEN:LowVoltageDetectorEnablecontrol
0:Disable
1:Enable
Bit3 Unimplemented,readas“0”
Bit2~0 VLVD2~VLVD0:LVDVoltageselection
000:2.0V
001:2.2V
010:2.4V
011:2.7V
100:3.0V
101:3.3V
110:3.6V
111:4.0V