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DS1302 RTC Chip

[Click the image to enlarge it]

Pin Configuration

Pin No.

Pin Name




Second supply input, when Vcc2 is greater than Vcc1 + 0.2V, DS1302 powers through this pin


X1 and X2

For connecting external crystal oscillator of 32.768kHz






This pin set to HIGH during a Read or a Write


I/O (Data Line)

This is the bi-directional data pin to 3-wire interface


SCLK(Serial Clock)

Used to synchronize data movement on the serial interface



Rechargeable energy source connected to this pin



  • Real-time clock counts minutes, seconds, date, hours, month day of the week, year and leap-year compensation upto 2100.
  • Single and Multiple (Burst mode) data transfer for Read and Write of Clock or RAM data
  • 31*8 battery-backed general purpose RAM
  • Simple interface using 3-wire
  • TTL-compatible
  • 2V to 5.5V full operation
  • Compact size
  • Available Package: 8-pin DIP, 8-pin SO


Technical Specifications

  • Supply voltage (typically): 3.3V
  • Voltage range on any pin (with respect to ground): -0.5V to 7.0°C
  • Operating Temperature (Commercial): 0°C to +70°C
  • Operating Temperature (Industrial): -40°C to +85°C
  • Storage Temperature range: -55°C to +125°C
  • Soldering Temperature: 260°C


Brief about DS1302 Chip and DS1302 RTC Module

DS1302 is a tickle-charge timekeeping chip which contains a real-time clock/calendar and 31 bytes of static RAM. DS1302 uses serial communication to interact with microcontrollers. Also, it automatically adjust the date for the month with fewer days. Clock operates in 24hr or 12hr format with an AM/PM indicator.

DS1302 chip is also commonly used as DS1302 RTC module which comes with a 32 kHz crystal and on-board battery backup all in a small SIP module that is compatible with a breadboard. DS1302 module are used by makers with Arduino, Raspberry Pi and other Micro-controllers.

A DS1302 RTC module pinout is shown in below image.

DS1302 RTC Module Pinout


Block Diagram Diagram of DS1302 RTC Chip

DS1302 Internal Block diagram


How to Use a DS1302 Chip

A typical operating circuit for DS1302 is given below. DS1302 have two power input, one is from cell and other is from controller. A crystal oscillator of 32.768 kHz is used to generate required frequency. For interfacing Data line, Reset Pin and Serial-clock pins of DS1302 are connected with the micro-controller.

 Circuit using DS1302



 DS1302 2D-model

 Dimension for DS1302 2D-model

Component Datasheet

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