Pad Description
Pad No.
Pad Name
I/O
Description
1
RD
I
READ clock input with pull-high resistor. Data in the RAM of the HT1625 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.
2
WR
I
WRITE clock input with pull-high resistor. Data on the DATA line are latched
into the HT1625 on the rising edge of the WR signal.
3
DATA
I/O
Serial data input or output with pull-high resistor
4
VSS
Negative power supply, ground
5
OSCI
I
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.
6
OSCO
O
7
VDD
Positive power supply
8
VLCD
I
LCD operating voltage input pad.
9
IRQ
O
Time base or Watchdog Timer overflow flag, NMOS open drain output
10, 11
BZ, BZ
O
2kHz or 4kHz tone frequency output pair
12~14
T1~T3
I
Not connected
15~22
COM0~COM7
O
LCD common outputs
23~86
SEG0~SEG63
O
LCD segment outputs
87
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 HT1625 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 HT1625 are all enabled.
Absolute Maximum Ratings
Supply Voltage......................................... 0.3V to 5.5V
Storage Temperature............................ 50 C to 125 C
Input Voltage.............................V
SS
0.3V to V
DD
+0.3V
Operating Temperature........................... 25 C to 75 C
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maximum Ratings 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.
HT1625
Rev. 1.10
5
September 11, 2002