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Real-Time Clocks

Feature-Rich, Low-Cost Timekeeping Solutions

A Real-Time Clock/Calendar (RTCC) maintains accurate time in an embedded system even when the main power is turned off.  Our RTCCs range from basic low-cost devices to highly integrated mid-range devices with either an I2C or SPI interface and include additional nonvolatile memory and a combination of features that are very useful when operating within a single battery-backed clock device. These cost-effective solutions offer more features and higher performance than many competitive devices and will meet the specific requirements of your application.

Why Choose Our RTCCs?

Innovative Peripherals

  • Battery switchover with power-fail timestamp
  • Wide digital trimming range
  • Watchdog timer with dual retriggers
  • Event detect inputs with a programmable debounce
  • Unique ID with a user unlock sequence

Easy to Implement

  • I2C and SPI interfaces
  • Industry-standard pinouts
    • I2C: 8 pins
    • SPI:  10 or 14 pins
  • RTCC-specific daughter boards that work with Microchip’s standard development platforms

Three Memory Options

  • Battery-backed SRAM
  • Nonvolatile EEPROM
  • Protected EEPROM area
    • Preprogrammed with unique EUI-48™ or EUI-64™ MAC address

Find The Right RTCC for Your Design

I2C RTCCs

I2C RTCC Block Diagram

Timing Features

  • Hours, minutes, seconds
  • Day of the week, day, month and year
  • Dual alarms: Single IRQ Out using VCC or VBAT
  • Programmable clock: 1 Hz to 32 kHz using VCC
  • Digital trimming from −127 ppm* to +127 ppm
    • Up to 11 seconds/day
  • Timestamp at battery switchover
    • VCC to VBAT
    • VBAT to VCC

Memory Options

  • 64 bytes SRAM
  • 1 Kbits SEEPROM
  • 64 bits Unique ID
    • 0 = Blank
    • 1 = EUI-48 MAC address
    • 2 = EUI-64 MAC address

Voltage and Current

  • Main power (oscillator running)
  • VCC = 1.8V to 5.5V
  • ICC = < 5 μA
    • Battery backup (timekeeping and RAM)
      • VBAT = 1.3V to 5.5V
      • IBAT = < 700 nA

*NOTE: 1 ppm ≈ 86 milliseconds/day

SPI RTCCs

SPI RTCC Block Diagram

Timing Features

  • Hours, minutes, seconds
    • Alarm down to 0.01 seconds
  • Day of the week, day, month and year
  • Dual alarms: Single IRQ Out using VCC or VBAT
  • Programmable clock out: 1 Hz to 32 kHz using VCC
  • 32 kHz boot clock at power up (MCP795BXX)
  • Digital trimming from −255 ppm* to +255 ppm
    • Up to 22 seconds/day
  • Timestamp at battery switchover
    • VCC to VBAT
    • VBAT to VCC
  • Watchdog timer
    • SPI retrigger
    • I/O retrigger

Memory Options

  • 64 bytes SRAM
  • 2 Kbits or 1 Kbits EEPROM
  • 128 bits Unique ID
  • 0 = Blank
  • 1 = EUI-48 MAC address
  • 2 = EUI-64 MAC address

Voltage and Current

  • Main power (oscillator running)
    • VCC = 1.8V to 5.5V
    • ICC = < 1 μA
  • Battery backup (timekeeping and RAM)
    • VBAT = 1.3V to 5.5V
    • IBAT = < 700 nA

*NOTE: 1 ppm ≈ 86 milliseconds/day

Get Started with These Development Tools

Use our Real-Time Clock PICtail™ daughter boards, along with a PICtail Plus Expansion Board and an Explorer 16/32 Development Board, to evaluate real-time clock functionality in microcontroller-based embedded applications.

MCP7941X PICtail Plus Daughter Board (I2C)

MCP79410 RTCC Board Learn More

MCP795XX PICtail Plus Daughter Board (SPI)

MCP795xx PICtail Plus Daughter Board Learn More

PICtail Plus Expansion Board

PICtail Plus Expansion Board
Learn More

Explorer 16/32 Development Board

Explorer 16/32 Development Board
Learn More

How Can You Use a RTCC in Your Application?

While there are many ways that RTCC technology can be used to enhance an embedded design, here are a few examples of how an RTCC can be used:

  • Enable wired and wireless communications between devices in smart energy applications using an RTCC with a MAC address
  • Use digital trimming in the RTCC to perform software temperature compensation for more accurate timekeeping in utility metering applications
  • Provide any Ethernet application with its own unique identification using the RTCC’s EUI-48 or EUI-64 MAC address
  • Display the time of day and date on the LCD in any embedded system

Additional Clock and Timing Technologies

Whatever your complex timing requirements are, we offer a comprehensive portfolio of technologies, services, and solutions to help you build more reliable systems. Visit our Clock and Timing page to learn more about our atomic clocks, buffers, crystals, oscillators and other timing products.