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.
This IC 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, it use a serial I/O transmission method to interface with a microprocessor. Only three wires are required: (1) RESTB, (2) SCLK and (3) I/O. Data can be delivered 1 byte at a time or in a burst of up to 8 bytes.
Operating voltage: 2.0V~5.5V
Maximum input serial clock:
500kHz at VDD=2V, 2MHz at VDD=5V
less than 0.5uA at 2V
less than 0.7uA at 3V
less than 1.0uA at 5V
– 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
HT1380A: 8-pin DIP package
HT1381A: 8-pin SOP package