HT1380 Datasheet, PDF (1/10 Pages) Holtek Semiconductor Inc – Serial Timekeeper Chip

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
- _{VIH: 2.0V~VDD+0.3V at VDD=5V}
- _{VIL: -0.3V~+0.8V at VDD=5V}
Applications
· Microcomputer serial clock
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.
Block Diagram
· 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
· Clock and Calendar
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.
Pin Assignment
I/O
S C LK
REST
D a ta S h ift
R e g is te r
C om m and
C o n tr o l L o g ic
R e a l T im e
C lo c k
O s c illa to r a n d
D iv id e r
C ir c u it
NC 1
X1 2
X2 3
VSS 4
8 VDD
NC 1
7 S C LK
X1 2
6 I/O
X2 3
5 REST VSS 4
8 VDD
7 S C LK
6 I/O
5 REST
X1
H T1380
X2
8 D IP
H T1381
8 SO P
1
October 2, 1999