Pad Description

Pad No.

Pad Name

I/O

Description

2

VO15N

O

Half voltage circuit output pin

3

VEE

¾

Double voltage circuit output pin

4~7

COM0~COM3

O

LCD common outputs

8~39

SEG0~SEG31

O

LCD segment outputs

40

CS

I

Chip selection input with pull-high resistor

When the CS is logic high, the data and command, read from or

written to the HT1620 are disabled. The serial interface circuit is

also reset. But if the CS is at logic low level and is input to the CS

pad, the data and command transmission between the host con-

troller and the HT1620 are all enabled.

41

RD

I

READ clock input with pull-high resistor

Data in the RAM of the HT1620 are clocked out on the falling

edge of the RD signal. The clocked out data will appear on the

DATA line. The host controller can use the next raising edge to

latch the clocked out data.

42

WR

I

WRITE clock input with pull-high resistor

Data on the DATA line are latched into the HT1620 on the rising

edge of the WR signal.

43

DATA

I/O Serial data input/output with pull-high resistor

44

VSS

¾

Negative power supply, Ground

45

OSCO

O

The OSCI and OSCO pads are connected to a 32.768kHz crystal

in order to generate a system clock.

46

OSCI

I

47

VDD

¾

Positive power supply

48

IRQ

O

Time base or WDT overflow flag, NMOS open drain output

49, 50

BZ, BZ

O

2kHz or 4kHz tone frequency output pair (tri-state output buffer)

51, 1

CC1, CC2

I

External capacitor pin, for double voltage and half voltage circuit

use

Absolute Maximum Ratings

Supply Voltage..............................-0.3V to 3.6V

Storage Temperature.................-50

Operating Temperature...............-25

Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maxi-

mum Ratings² may cause substantial damage to the device. Functional operation of this de-

vice at other conditions beyond those listed in the specification is not implied and prolonged

exposure to extreme conditions may affect device reliability.

HT1620

6

July 26, 1999