Last Updated on March 16, 2024
To Control Time depended applications we need Real time clock circuitry, some microcontrollers has their own internal RTC but most low price microcontroller don’t have RTC internally, this article will help you to find most suitable RTC chip for your Embedded project.
Real Time Clock shortly known as RTC, it makes count on second, minute, hour and days and even years.
Typical RTC interface
Now a days digital RTC ICs are uses I²C technology to communicate with microcontroller and processors. That is it uses only two wires (serial clock) SCL and (serial data) SDA. So it is very easy to interface with micro controller that having I²C lines.
Every RTC chip needs clock pulse hence they provided with crystal element and to maintain interrupt free operation a stand alone battery also provided to RTC chip.
Here most used RTC ICs are listed out with pin configurations.
- DS1307 – 64 x 8, Serial, I2C Real-Time Clock.
- DS3234 – Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM
- DS3231 – Extremely Accurate I2C-Integrated RTC/TCXO/Crystal
- DS1302 – Trickle-Charge Timekeeping Chip
- DS1308 – Low-Current I²C RTC with 56-Byte NV RAM
- PCF8563 – Real-time clock/calendar
- MCP79400 – Real-Time Clock/Calendar with SRAM and Protected EEPROM
IC DS1307-64 x 8, Serial, I2C Real-Time Clock
The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information.[DS1307 datasheet]
DS3234-Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM
The DS3234 is a low-cost, extremely accurate SPI™ bus real-time clock (RTC) with an integrated temperature compensated crystal oscillator (TCXO) and crystal. The DS3234 incorporates a precision, temperature-compensated voltage reference and comparator circuit to monitor VCC.[DS3234 datasheet]
DS3231 – Extremely Accurate I2C-Integrated RTC/TCXO/Crystal
The DS3231 is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperaturecompensated crystal oscillator (TCXO) and crystal. The device incorporates a battery input, and maintains accurate timekeeping when main power to the device is interrupted.[DS3231 datasheet]
DS1302 – Trickle-Charge Timekeeping Chip
The DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM. It communicates with a microprocessor via a simple serial interface. The real-time clock/calendar provides seconds, minutes, hours, day, date, month, and year information.[DS1302 datasheet]
DS1308 – Low-Current I²C RTC with 56-Byte NV RAM
The DS1308 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV RAM. Address and data are transferred serially through an I2C interface. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information.[DS1308 datasheet]
PCF8563 – Real-time clock/calendar
The PCF8563 is a CMOS1 Real-Time Clock (RTC) and calendar optimized for low power consumption. A programmable clock output, interrupt output, and voltage-low detector are also provided. All addresses and data are transferred serially via a two-line bidirectional I2C-bus. Maximum bus speed is 400 kbit/s. The register address is incremented automatically after each written or read data byte. [PCF8563 datasheet]
MCP79400 – Real-Time Clock/Calendar with SRAM and Protected EEPROM
The MCP7940X Real-Time Clock/Calendar (RTCC) tracks time using internal counters for hours, minutes, seconds, days, months, years, and day of week. Alarms can be configured on all counters up to and including months. For usage and configuration, the MCP7940X supports I2C communications up to 400 kHz. [mcp79400 datasheet]