Pad Description

Pad No.

Pad Name

I/O

Description

1

DATA

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

2

VSS

¾ Negative power supply, ground

3

OSCI

I

Crystal oscillator input pin

4

OSCO

O Crystal oscillato output pin

5

VDD

¾ Positive power supply

6

VLCD

I

LCD operating voltage input pad.

7

IRQ

O Time base or watchdog timer overflow flag, NMOS open drain

output

8, 9

BZ, BZ

O 2kHz or 4kHz tone frequency output pair (Tristate output

buffer)

10~13

T1~T4

I

Not connected

14~29

COM0~COM15

O LCD common outputs

30~93

SEG0~SEG63

O LCD segment outputs

94

CS

I

Chip selection input with pull-high resistor. When the CS is

logic high, the data and command read from or write to the

HT16270 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 controller

and the HT16270 are all enabled.

95

RD

I

READ clock input with pull-high resistor. Data in the RAM of

the HT16270 are clocked out on the rising edge of the RD sig-

nal. The clocked out data will appear on the data line. The host

controller can use the next falling edge to latch the clocked out

data.

96

WR

I

WRITE clock input with pull-high resistor. Data on the DATA

line are latched into the HT16270 on the rising edge of the WR

signal.

Absolute Maximum Ratings

Supply Voltage .............................-0.3V to 5.5V

Storage Temperature.................-50°Cto125°C

Operating Temperature ..............-25°Cto75°C

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 device

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

sure to extreme conditions may affect device reliability.

HT16270

5

April 21, 2000