HT45F3W datasheet(140/167 Pages) HOLTEK

140 / 167 page

Rev. 1.50

140

De�e��e� 01� �01�

Rev. 1.50

141

De�e��e� 01� �01�

HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

Charge Pump and Voltage Regulator

Theredeviceincludesachargepumpandonevoltageregulatorforgenerationofaconstant3.3Vvoltage.

Operation

Thechargepumpcanbeenabledordisableddependingontheapplication.Thechargepumpacts

asavoltagedoublerwithVDDasitsinput.Theoutputvoltageofchargepumpwillthereforebe

VDD×2.Thisvoltageisprovidedtotheregulatorinputwhichwillinturngenerateastable3.3V

voltage,whichcanbeusedbytheA/Dconverterorasanexternalsensorexcitationvoltageorother

applications.Itisnecessarythatthechargepumpprovidesaminimumoutputvoltageofgreaterthan

3.6Vtoprovidetheregulatorwithitsminimumoperatingvoltageforproper3.3Vvoltagegeneration.

Theblockdiagramofthesetwofunctionsisshownbelow:

Cha�ge Pu�p

(Voltage Dou�le�)

Regulato�

(3.3V)

ADC

OPA

WDT

PGA

SCF

VOCHP

VOREG

CHPC1

CHPC�

VDDCH

VDDCH x �

Divide�

CHPCKD

REGCEN

CHPEN

VDDCH

VSSCH

3.3V

Thechargepumpapplicationcircuitisshownbelow:

HT45F3W

CHPC1

PC�/CHPC�

VOCHP

VOREG/AVDD

VSS/AVSS/VSSCH

C�

Charge pump Circuit

Note:1.C1uses10μFMLCCcapacitor.

2.C2andC3use1μF~10μFElectrolyticcapacitor

3.WhenenteringtheHALTmode,thehardwarewillturnofftheChargepumpautomaticallyto

preventthechargepumpoutputbeinginanunknownstate.DuringthistimetheLCDcannotbe

used.

HT45F3W Datasheet(PDF) 140 Page - Holtek Semiconductor Inc

HT45F3W Datasheet(HTML) 140 Page - Holtek Semiconductor Inc

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