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I²C™ & SPI Family Brochure Datasheet by Microchip Technology
View All Related Products | Download PDF Datasheet
Q
MICROCHIP
Serial Real-Time Clock/Calendar
Low-Cost Timekeeping Solution
Summary
Microchip’s portfolio of Real-Time Clock/Calendars
(RTCCs) offer low-cost system timekeeping solution. Real-
Time Clock/Calendars track time with resolutions as small
as 1/100th of a second and issue alarms on a wide variety
of time conditions.
The RTCC maintains accurate time through system
shutdowns by automatically switching over to an external
battery back-up source. RTCC’s are designed to operate
using a 32.768 kHz quartz crystal and can digitally
compensate for frequency variance caused by crystal
tolerance and temperature. Microchip RTCC’s have a I2C™
or SPI interface for configuration, reading and writing the
time. Additionally, alarm interrupt requests, square wave
output and system reset control signals are available on
dedicated pins.
Microchip’s RTCCs are available with a range of internal
memories including battery-backed SRAM, non-volatile
EEPROM and an additional area of protected EEPROM.
The protected EEPROM area is only writable after the
RTCC receives an unlock sequence and is available
pre-programmed with unique EUI-48™ or EUI-64™ MAC
address. Custom programming is also available.
Key Features and Benefits
Features Benefits
Automated timekeeping Offload timekeeping tasks, including leap year management to the RTCC
Dual alarms System controller can attend to other tasks and have the RTCC indicate a specific time has been reached
Battery back-up Maintain time through system powerdowns and preserve SRAM contents
Time stamp Capture the time when system power was lost and restored
Versatile clock-out/alarm/output pin The RTCC can produce a squarewave for the system, or wake a processor from a low-power state on a time
match to indicate an alarm has occurred
64-bytes battery backed SRAM Unlimited endurance non-volatile data storage for data that needs to be maintained through a shutdown
Digital oscillator trimming/calibration Adjust for crystal frequency tolerance and drift to maintain accurate time
Up to 128-bit protected EEPROM area Robust non-volatile storage. Only writable after an unlock sequence
Pre-programmed EUI MAC ID Unique identifier in every device which can be used as a serial number or as a network MAC ID. Using a pre-
programmed MAC ID avoids the expense of purchasing an ID block and serialized programming
Up to 2 Kb general purpose EEPROM Long-term storage of parameters, system modes, calibration information and data through shutdowns
Watch-dog timer Guards against the controller software getting trapped in a loop or awaiting an event
Debounced input event detect Places the system controller in a low-power state and has the RTCC detect a true event from a noisy sensor
Transition count event detect The RTCC can alert the system once it records a specific number of logic-level transitions on a signal, allowing
monitoring to be delegated to the RTCC
Available Reference Materials
■Hardware design guidance
■Circuit schematics and gerber files
■Characterized crystal recommendations
■Code examples
■Migration guides
■Configuration directions
■Debugging guides
■User support forum
SRAM
EEPROM
Alarm
Time Stamp
Timekeeping
Event Handler
WDT
Serial Interface
System reset*
Interrupt
or
Transition
count event
detection*
Debounced input*
*Optional
System
Controller
Supply
Inna
llh’l'lfl’m“
MICROCHIP
Microcontrollers - Digital Signal Controllers - Analog - Memory 0 Wireless
Information subject to change. The Microchip name and logo and the Microchip logo are registered trademarks and PICDEM and PICtail are trademarks of Microchip Technology Incorporated in the U.S.A. and
other countries. All other trademarks mentioned herein are property of their respective companies. © 2014, Microchip Technology Incorporated. All Rights Reserved. Printed in the U.S.A. 7/14
DS20005074B
Visit our web site for additional product information and to locate your local sales office.
Microchip Technology Inc. • 2355 W. Chandler Blvd. • Chandler, AZ 85224-6199
www.microchip.com/clock
Low-Cost Real-Time Clock Calendar Portfolio
Product Pins Interface Battery
Back-up
Protected EEPROM
Area (bits)
Protected
EEPROM Contents
General Purpose
EEPROM (Kbits)
Watchdog Timer
and Event Detects
MCP7940M 8 I2C™ – – N/A – –
MCP7940N 8 I2Cü– N/A – –
MCP79400 8 I2Cü64 – – –
MCP79401 8 I2Cü64 EUI-48 – –
MCP79402 8 I2Cü64 EUI-64 – –
MCP79410 8 I2Cü64 – 1 –
MCP79411 8 I2Cü64 EUI-48 1 –
MCP79412 8 I2Cü64 EUI-64 1 –
MCP79510 10 SPI ü128 – 1 –
MCP79511 10 SPI ü128 EUI-48 1 –
MCP79512 10 SPI ü128 EUI-64 1 –
MCP79520 10 SPI ü128 – 2 –
MCP79521 10 SPI ü128 EUI-48 2 –
MCP79522 10 SPI ü128 EUI-64 2 –
MCP795W10 14 SPI ü128 – 1 ü
MCP795W11 14 SPI ü128 EUI-48 1 ü
MCP795W12 14 SPI ü128 EUI-64 1 ü
MCP795W20 14 SPI ü128 – 2 ü
MCP795W21 14 SPI ü128 EUI-48 2 ü
MCP795W22 14 SPI ü128 EUI-64 2 ü
Power-Fail Time-Stamp Development Tools from Microchip
To support our Real-Time Clock/Calendar products, we
offer two PICtail™ daughter boards, each with a
characterized crystal oscillator circuit and an on-board
coin cell battery for use as a back-up supply. Compatible
code development platforms include the PICDEM™ PIC18
Explorer Board (DM183032) and the Explorer 16
Development Board (DM240001).
Supply
Voltage
Time
Battery
back-up
switch over
voltage
Time captured
by power-fail
timestamp
Time captured
by power-up
timestamp
Loss of
system power
MCP795XX RTCC PICtail
Daughter Board
(AC164147)
MCP79410 RTCC PICtail
Plus Daughter Board
(AC164140)
