Pad Description

Pad Name

I/O

Internal

Connection

Description

SEG1~SEG30

O

CMOS OUT

LCD segment signal output pads

COM1~COM3

O

CMOS OUT

LCD common signal output pads

HK

I

CMOS IN

Pull-high

Hook switch detector input

Active low

S2

I

CMOS IN

Pull-low

Clock adjusting switch

Active high

X2

O OSCILLATOR 32768Hz crystal oscillator output

X1

I

OSCILLATOR 32768Hz crystal oscillator input

T2

I

CMOS IN

Pull-high

Test pad (connected to VSS for production test)

T1

I

CMOS IN

Pull-high

Test pad (connected to VSS for production test)

INT

O

NMOS OUT

Interrupt output, 2Hz (default) or 16Hz (by mask option)

TIMER

I

CMOS IN

Pull-low

Timer reset and start/hold toggle control input pad

12/24

I

CMOS IN

Pull-low

12-hour or 24-hour format option pad, connected to VDD for 12-hour format

S1

I

CMOS IN

Pull-low

Clock setting switch

Active high

DI

I

CMOS IN

Pull-high

Serial data input pad (connected to the dialer)

Data should be valid at the falling edge of SK

SK

I

CMOS IN

Pull-high

Clock input pad (connected to the dialer)

VA

O

CMOS OUT

Voltage doubler, connected to the external capacitor

VB

O

CMOS OUT

Voltage doubler, connected to the external capacitor

VC

O

CMOS OUT

Voltage doubler, connected to the external capacitor

VDD

¾¾

Positive power supply

VSS

¾¾

Negative power supply, ground

Approximate internal connection circuit

HT1611C

Rev. 1.10

3

August 17, 2001

NM O S O UT

CM O S I N

Pul l - l o w

CM O S I N

Pul l - h i g h

OS C I L L A T OR

CM O S O UT

X1

X2

12pF

15pF

10M W