Features

Operating voltage: 2.0V~5.5V

Maximum input serial clock: 500kHz at VDD=2V,

2MHz at VDD=5V

Operating current: less than 1A at 2V,

less than 1.2A at 5V

TTL compatible

 VIH: 2.0V~VDD+0.3V at VDD=5V

 VIL: 0.3V~+0.8V at VDD=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

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 automatically adjusted. The

HT1380/HT1381 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 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 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.