HT47C20L datasheet(5/55 Pages) HOLTEK

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Pin Description

Pin Name

I/O

Mask

Option

Function

RES

Schmitt trigger reset input. Active low.

PA0/BZ

PA1/BZ

PA2

PA3/PFD

PA4~PA7

I/O

Wake-up

Pull-high

or None

CMOS or

NMOS

Bidirectional 8-bit input/output port. The low nibble of the PA

can be configured as CMOS output or NMOS output with or

without pull-high resistors (mask option). NMOS output can be

configured as schmitt trigger input with or without pull-high

resistors. Each bit of NMOS output can be configured as wake

up input by mask option. Of the eight bits, PA0~PA1 can be set

as I/O pins or buzzer outputs by mask option. PA3 can be set as

an I/O pin or a PFD output by mask option.

PB0/INT

PB1

PB2/TMR

PB3

Four-bit schmitt trigger input port. The PB is configured as

with pull-high resistors. Of the four bits, PB0 can be set as an

input pin or an external interrupt input pin (INT) by software

application. While PB2 can be set as an input pin or a

timer/event counter input pin by software application.

VSS

¾¾

Negative power supply, GND

V1~V3, C1~C2 ¾¾

Voltage pump

SEG19/COM3

COM2~COM0

1/2 or 1/3

or 1/4

Duty

SEG19/COM3 can be set as a segment or a common output

driver for LCD panel by mask option. COM2~COM0 are out-

puts for LCD panel plate.

SEG18~SEG0

LCD driver outputs for LCD panel segments

VDD

¾¾

Positive power supply

OSC2

OSC1

OSC1 and OSC2 are connected to a 32768Hz crystal for the in-

ternal system clock and WDT source.

IN0

CS0

RS0

CRT0

RT0

Oscillation input pin of channel 0

Reference capacitor connection pin of channel 0

Reference resistor connection pin of channel 0

Resistor/capacitor sensor connection pin for measurement of

channel 0

Resistor sensor connection pin for measurement of channel 0

IN1

CS1

RS1

RT1

Oscillation input pin of channel 1

Reference capacitor connection pin of channel 1

Reference resistor connection pin of channel 1

Resistor sensor connection pin for measurement of channel 1

TEST

TEST mode input pin with pull-high resistor.

It disconnects in normal operation.

HT47C20L

January 18, 2000

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