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

X1

I

OSCILLATOR

32768Hz crystal oscillator input

X2

O

32768Hz crystal oscillator output

T1

I

CMOS IN

Pull-high

Test pad (connected to VSS for production test)

T2

I

CMOS IN

Pull-high

Test pad (connected to VSS for production test)

INT

O

NMOS OUT

Interrupt output, 8Hz 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

S2

I

CMOS IN

Pull-low

Clock adjusting 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)

RES

I

CMOS IN

Pull-high

System initialization pin (active low)

The pull-high resistance is 200kW typ.

RT

I

CMOS

LATCH IN

Pull-low

Real time selection pin

VDD: With real time mode

Floating: Without real time mode

EPN

I

CMOS

LATCH IN

Pull-high

Extension phone number display selection pin

VSS: Without extension phone number display

Floating: With extension phone number display

ACT

I

CMOS

LATCH IN

Pull-high

In the dialing number display mode, auto change to timer mode selection

VSS: Auto change to timer mode

Floating: Manual change to timer mode

VA

O

CMOS OUT

Voltage doubler, connected to external capacitor

VB

O

CMOS OUT

Voltage doubler, connected to external capacitor

VC

O

CMOS OUT

Voltage doubler, connected to external capacitor

VDD

¾¾

Positive power supply

VSS

¾¾

Negative power supply, ground

HT1613C

Rev. 1.10

3

August 17, 2001