PATENTED
HT1626
Pad Description
Pad No.
Pad Name
I/O
Description
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 instead, the OSCI and OSCO pads
can be left open.
1
OSCI
I
2
OSCO
O
¾
I
3
VDD
Positive power supply
4
VLCD
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
5
IRQ
O
O
I
6, 7
8~11
12~27
28~75
BZ, BZ
T1~T4
COM0~COM15
SEG0~SEG47
O
O
LCD common outputs
LCD segment outputs
Chip selection input with pull-high resistor. When the CS is logic high, the
data and command read from or write to the HT1626 are disabled. The se-
rial interface circuit is also reset. But if the CS is at logic low level and is in-
put to the CS pad, the data and command transmission between the host
controller and the HT1626 are all enabled.
76
CS
I
READ clock input with pull-high resistor. Data in the RAM of the HT1626 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 rising edge to
latch the clocked out data.
77
78
RD
I
I
WRITE clock input with pull-high resistor. Data on the DATA line are latched
into the HT1626 on the rising edge of the WR signal.
WR
79
80
DATA
VSS
I/O Serial data input or output with pull-high resistor
Negative power supply, ground
¾
Absolute Maximum Ratings
Supply Voltage .........................................-0.3V to 5.5V
Input Voltage.............................VSS-0.3V to VDD+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 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.
Rev. 1.50
5
June 9, 2009
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
