DS1302 RTC Real-Time Clock IC DIP-8 🕒

The DS1302 is a low-power Real-Time Clock (RTC) and calendar IC with integrated trickle-charger and 31-byte SRAM, designed for precise timekeeping in embedded systems. It uses an external 32.768 kHz crystal and a simple 3‑wire serial interface for easy integration with Arduino, Raspberry Pi, and other microcontroller-based projects. Ideal for electronics components libraries and RTC modules, it operates from 2.0 V to 5.5 V with ultra-low timekeeping current for extended backup life.

Key Features ✨

• Full real-time clock/calendar tracks seconds, minutes, hours, day, date, month, and year.
• Leap-year compensation valid up to the year 2100.
• 31 × 8 static RAM for scratchpad data storage.
• 3-wire serial I/O (CE, I/O, SCLK) minimizes pin count and supports burst transfers.
• Wide operating voltage: 2.0 V to 5.5 V for flexible system design.
• Ultra-low timekeeping current: typically less than 300 nA at 2.0 V.
• Programmable trickle charger to maintain a rechargeable cell or supercapacitor on the backup input.
• Automatic power-fail detection and switchover to backup supply to preserve time and RAM.
• BCD-coded registers simplify software parsing.
• DIP-8 package for easy prototyping and through-hole assembly.

Technical Specifications ⚙️

• Supply Voltage (VCC2): 2.0 V to 5.5 V
• Backup Supply (VCC1): 2.0 V to 5.5 V (with programmable trickle-charge path)
• Timekeeping Current: less than 300 nA at 2.0 V (typ.)
• Interface: 3‑wire serial (CE, I/O, SCLK; SPI-like, not SPI-native)
• Serial Clock Rate: up to approximately 1 MHz
• Oscillator: external 32.768 kHz crystal (no external load capacitors typically required)
• RAM: 31 × 8 bytes
• Calendar Range: Year 00–99 with leap-year compensation to 2100
• Package Type: DIP-8
• Operating Temperature: -40°C to +85°C
• Storage Temperature: -55°C to +125°C
• Power Consumption: ultra-low power timekeeping mode

Pin/Signal Overview 🔌

• CE: Chip Enable (active high)
• I/O: Bidirectional data line
• SCLK: Serial clock input
• X1/X2: 32.768 kHz crystal connections
• VCC2: Main supply
• VCC1: Backup supply (battery/supercap, trickle-charge supported)
• GND: Ground

Compatibility and Integration 🤖

• Works with Arduino, Raspberry Pi, ESP32/ESP8266, and other microcontrollers via a simple bit-banged 3‑wire interface.
• Suitable for both 5 V and 3.3 V logic systems; use level shifting if the DS1302 is powered at 5 V and the MCU is 3.3 V.
• Connect a 32.768 kHz crystal to X1/X2 and a backup source (coin cell or supercap) to VCC1 for continuous timekeeping.
• Add local decoupling capacitors near the IC for best performance.

Applications 💡

• Real-time clocks in computers and embedded systems
• Time-critical applications and scheduling
• Data logging with timestamping
• Alarm systems and timed control
• GPS systems and portable instruments
• DIY electronics modules for learning and prototyping

Why Choose DS1302? ✅

• Combines RTC, backup management, and SRAM in a compact DIP-8 package.
• Low power design maximizes backup battery or supercap life.
• Easy to interface with popular platforms and electronics components ecosystems.