HT1380 Real-Time Clock IC – Serial RTC/Calendar – SOIC-8 – Holtek

The Holtek HT1380 is a low-power Real-Time Clock (RTC) and calendar IC designed for accurate timekeeping in compact embedded systems. Supplied in a space-efficient SOIC-8 (SOP-8) surface-mount package, it is ideal for high-density PCB designs used in consumer electronics, industrial controls, security devices, metering systems, and data loggers.

The HT1380 provides full time and calendar functions, including seconds, minutes, hours, day, date, month, and year, with automatic leap-year correction. Communication is handled through a simple 3-wire serial interface (RST, SCLK, I/O), making it easy to integrate with a wide range of microcontrollers. All timekeeping data is stored in BCD (Binary Coded Decimal) format for simplified software processing.

Operating across 2.0V to 5.5V, the IC supports both low-voltage and standard logic systems while maintaining ultra-low standby current (<1µA at 5V), making it ideal for battery-powered applications. An external 32.768 kHz crystal oscillator is required to ensure stable and accurate clock operation.

Key Specifications:

• Manufacturer: Holtek

• Part Number: HT1380

• Function: Real-Time Clock/Calendar

• Interface: 3-wire serial (RST, SCLK, I/O)

• Time Format: BCD-coded registers

• Operating Voltage: 2.0V to 5.5V

• Standby Current: <1µA typical at 5V

• External Crystal: 32.768 kHz

• Timekeeping Modes: 12-hour (with AM/PM) and 24-hour

• Automatic leap-year compensation

• Package: SOIC-8 / SOP-8 (surface mount)

Package Includes:
1 x HT1380 Real-Time Clock IC (SOIC-8)

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