HT1622
Pad Description
Pad No.
Pad Name
I/O
Description
Chip selection input with Pull-high resistor. When the CS is logic
high, the data and command read from or written to the HT1622
are disabled. The serial interface circuit is also reset. But if CS is
at logic low level and is input to the CS pad, the data and com-
mand transmission between the host controller and the HT1622
are all enabled.
READ clock input with Pull-high resistor. Data in the RAM of
the HT1622 are clocked out on the rising edge of the RD signal.
The clocked out data will appear on the data line. The host con-
troller can use the next falling edge to latch the clocked out data.
WRITE clock input with Pull-high resistor. Data on the DATA
line are latched into the HT1622 on the rising edge of the WR sig-
nal.
Negative power supply, ground
If the system clock comes from an external clock source, the ex-
ternal clock source should be connected to the OSCI pad.
Positive power supply
LCD operating voltage input pad
Time base or Watchdog Timer overflow flag, NMOS open drain
output
2kHz or 4kHz tone frequency output pair
Not connected
LCD common outputs
LCD segment outputs
1
CS
I
2
RD
I
3
4
5
6
7
8
9
10, 11
12~14
15~22
23~54
WR
DATA
VSS
OSCI
VDD
VLCD
IRQ
BZ, BZ
T1~T3
COM0~COM7
SEG0~SEG31
I
I/O Serial data input/output with Pull-high resistor
¾
I
¾
I
O
O
I
O
O
Absolute Maximum Ratings
Supply Voltage..............................-0.3V to 5.5V
Input Voltage ................V
SS
-0.3V
to V
DD
+0.3V
Storage Temperature.................-50°C to 125°C
Operating Temperature ..............-25°C to 75°C
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maxi-
mum Ratings 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.
5
April 21, 2000
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
