Pad Description

Pad No.

Pad Name

I/O

Description

1~42

96~181

SEG86~SEG127

SEG0~SEG85

O

LCD segment outputs

43~58

80~95

COM31~COM16

COM0~COM15

O

LCD common outputs, under 144

´16 command mode, COM16~COM31 will

share to SEG128~SEG143. COM31/SEG128, COM30/SEG129, COM29/

SEG130....., COM18/SEG141, COM17/SEG142, COM16/SEG143

59

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 HT1670 are disabled. The serial

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

the CS pad, the data and command transmission between the host controller

and the HT1670 are all enabled.

60

RD

I

READ clock input with pull-high resistor. Data in the RAM of the HT1670 are

clocked out on the falling edge of the RD signal. The clocked out data will ap-

pear on the data line. The host controller can use the next rising edge to latch

the clocked out data.

61

WR

I

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

into the HT1670 on the rising edge of the WR signal.

62~65

DB0~DB3

I/O

Parallel data input/output with a pull-high resistor

66

VSS

¾ Negative power supply for logic circuit, ground

67

68

OSCI

OSCO

I

O

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

generate a system clock. If the system clock comes from an external clock

source, the external clock source should be connected to the OSCI pad. But

if an on-chip RC oscillator is selected, the OSCI and OSCO pads can be left

open.

69

VDD

¾ Positive power supply for logic circuit

70, 79

VLCD

I

Power supply for LCD driver circuit

71

IRQ

O

Time base or Watchdog Timer overflow flag, NMOS open drain output.

72, 73

BZ, BZ

O

2kHz or 4kHz frequency output pair (tristate output buffer)

74~78

T1~T4, T000

I

Vary bias current pin

It is usually not connected

Absolute Maximum Ratings

Storage Temperature ............................

-50°Cto125°C

Operating Temperature...........................

-25°Cto75°C

Note: These are stress ratings only. Stresses exceeding the range specified under

²Absolute Maximum 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 exposure to extreme conditions may affect device reliabil-

ity.

HT1670

Rev. 1.10

5

September 17, 2004