HT1380A/HT1381A
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 0.5μA at 2V
–
less than 0.7μA at 3V
–
less than 1.0μA at 5V
• TTL compatible
–
V
IH
: 2.0V~V
DD
+0.3V at V
DD
=5V
–
V
IL
: 0.3V~+0.8V at V
DD
=5V
• Two data transmission modes: single-byte, or burst
mode
• Serial I/O transmission
• All registers store BCD format
• HT1380A: 8-pin DIP package
HT1381A: 8-pin SOP package
General Description
The HT1380A/HT1381A 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 automatically adjusted.
The HT1380A/HT1381A is designed 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 HT1380A/HT1381A 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 HT1380A/HT1381A use a serial 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 delivered 1 byte at a time or in a burst of
up to 8 bytes.
Applications
• Microcomputer serial clock
• Clock and Calendar
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
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
Pin Assignment
N C
X 1
X 2
V S S
4
5
H T 1 3 8 0 A
8 D IP -A
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
H T 1 3 8 1 A
8 S O P -A
3
6
2
7
1
8
V D D
S C L K
I/O
R E S T
Rev. 1.00
1
June 15, 2012
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
