HT1380/HT1381
Serial Timekeeper Chip
Features
·
·
·
·
Operating voltage: 2.0V~5.5V
Maximum input serial clock: 500kHz at
V
DD
=2V, 2MHz at V
DD
=5V
Operating current: less than 400nA at 2V,
less than 1.2mA at 5V
TTL compatible
-
V : 2.0V~V
IH
DD
+0.3V at V
DD
=5V
-
V :
-0.3V~+0.8V
at V
IL
DD
=5V
·
·
·
·
Two data transmission modes: single-byte,
or burst mode
Serial I/O transmission
All registers store BCD format
HT1380: 8-pin DIP package
HT1381: 8-pin SOP package
Applications
·
Microcomputer serial clock
·
Clock and Calendar
General Description
The HT1380/HT1381 is a serial timekeeper IC
which provides seconds, minutes, hours, day,
date, month and year information. The number
of days in each month and leap years are auto-
matically adjusted. The HT1380/HT1381 is de-
signed for low power consumption and can
operate in two modes: one is the 12-hour mode
with an AM/PM indicator, the other is the
24-hour mode.
The HT1380/HT1381 has several registers to
store the corresponding information with 8-bit
data format. A 32768Hz crystal is required to
provide the correct timing. In order to minimize
the pin number, the HT1380/HT1381 use a se-
rial I/O transmission method to interface with a
microprocessor. Only three wires are required:
(1) REST, (2) SCLK and (3) I/O. Data can be de-
livered 1 byte at a time or in a burst of up to 8
bytes.
Block Diagram
I/O
S C L K
D a ta S h ift
R e g is te r
R e a l T im e
C lo c k
Pin Assignment
N C
X 1
X 2
V S S
4
5
3
6
2
7
1
8
V D D
S C L K
I/O
R E S T
N C
X 1
X 2
V S S
4
5
3
6
2
7
1
8
V D D
S C L K
I/O
R E S T
R E S T
C o m m a n d
C o n tr o l L o g ic
O s c illa to r a n d
D iv id e r
C ir c u it
X 1
X 2
H T 1 3 8 0
8 D IP
H T 1 3 8 1
8 S O P
1
October 2, 1999
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
