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.

FEATUREs
• Operating voltage: 2.0V~5.5V
• Maximum input serial clock: 500kHz at VDD=2V, 2MHz at VDD=5V
• Operating current:
   – less than 0.5μA at 2V
   – less than 0.7μA at 3V
   – less than 1.0μA 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
• HT1380A: 8-pin DIP package
  HT1381A: 8-pin SOP package
 
Applications
• Microcomputer serial clock
• Clock and Calendar