Pad Description

Pad Name

I/O

Internal

Connection

Description

SEG1~SEG48

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

S1

I

CMOS IN

Pull-low

Clock setting switch

Hour or minute can be selected for S2 adjustment

RES

I

CMOS IN

Pull-high

System initialization pin, active low

The pull-high resistance is 200kW typ.

MODE

I

CMOS IN

Pull-low

4 or 5 bits pattern selection pad

VDD: 5 bits pattern

Floating: 4 bits pattern

12/24

I

CMOS IN

Pull-low

12-hour or 24-hour format option pad

VDD: 12-hour format

Floating: 24-hour format

S2

I

CMOS IN

Pull-low

Clock adjusting switch

Hour or minute digits can be adjusted depending upon the S1 selection

DI

I

CMOS IN

Pull-high

Serial data input pad

Data should be valid at the falling edge of SK (connected to the dialer)

SK

I

CMOS IN

Pull-high

Clock input pad (connected to the dialer), active low

Input data is latched at the falling edge of SK

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)

X1

I

OSCILLATOR

32768Hz crystal oscillator input

X2

O

32768Hz crystal oscillator output

TIMER

I

CMOS IN

Pull-low

Timer reset-and-start/hold toggle control input pad

INT

O

NMOS OUT

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

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 circuits

HT1616C

Rev. 1.10

3

September 13, 2001

12pF

NM O S O UT

CM O S I N

Pu l l - l o w

CM O S I N

Pu l l - h i g h

OS C I L L A T OR

CM O S O UT

X1

X2

15pF

10M W