MCP7940N

The MCP7940N series of low-power Real-Time Clocks (RTC) uses digital timing compensation for an accurate clock/calendar, a programmable output control for versatility, and a power sense circuit that automatically switches to the backup supply. Using a low-cost 32.768 kHz crystal, it tracks time using several internal registers. For communication, the MCP7940N uses the I2C™ bus. The clock/calendar automatically adjusts for months with fewer than 31 days, including corrections for leap years. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator and settable alarm(s) to the second, minute, hour, day of the week, date or month. Using the programmable CLKOUT, frequencies of 32.768, 8.192 and 4.096 kHz and 1 Hz can be generated from the external crystal. The device is fully accessible through the serial interface while VCC is between 1.8V and 5.5V, but can operate down to 1.3V for timekeeping and SRAM retention only.

Features
  • Battery-Backed Real-Time Clock/Calendar (RTCC)
  • Hours, Minutes, Seconds, Day of Week, Day, Month, Year
  • Leap year compensated  to 2399
  • 12/24 hour modes
  • On-Chip Digital Trimming/Calibration
  • 1 PPM Resolution
  • ±129 PPM Range
  • Dual Programmable Alarms
  • Versatile Output Pin
  • Clock output with selectable frequency
  • Alarm output
  • General Purpose output
  • Power-Fail Time-Stamp Time logged on switchover to and from Battery Backup
  • Time logged on switchover to and from Battery Backup
  • 64 Bytes Battery-Backed SRAM
  • 2-Wire Serial Interface, I2C™Compatible I2C Clock Frequency up to 400 kHz
  • I2C Clock Frequency up to 400 kHz
  • Wide Voltage Range Operating Voltage 1.8V to 5.5V Backup Voltage 1.3V to 5.5V
  • Operating Voltage 1.8V to 5.5V
  • Backup Voltage 1.3V to 5.5V
  • Low Typical Timekeeping Current
  • Automatic Switchover to Battery Backup
Parameter
Parameter Name Value Value
Max Communications Speed 400 kHz 400 kHz
Pin Count 8 8
Minimum Clock Count (seconds) 1 sec 1 sec
Battery-backed SRAM (Bytes) 64 64
Temperature Range (C) -40 to +125 -40 to +125
Documents
MCP7940N Low-Cost I2C Real-Time Clock/Calendar with SRAM and Battery SwitchoverData Sheets03/20/20141351KB
MCP7940N Family Silicon ErrataErrata12/15/201570KB
Maxim DS1307 to MCP7940N MigrationMigration Documents03/07/2013326KB
Maxim DS1338 to MCP7940N MigrationMigration Documents03/28/2013317KB
ST M41T11 to MCP7940N MigrationMigration Documents04/09/2013344KB
AN1355 - A Complete Electronic Watch Based on MCP79410 I2C? RTCCAppNote06/23/2016154KB
AN1364 - Using the Alarm Feature on the MCP79410 RTCC to Implement a Delayed AlarmAppNote10/20/2010123KB
AN1365 - Recommended Usage of Microchip Serial RTCC DevicesAppNote03/28/2013267KB
AN1413 - Temperature Compensation of a Tuning Fork Crystal Based on MCP79410AppNote11/07/2011479KB
AN1414 - Using HI-TECH C Compiler to Interface RTCC Devices to 8-Bit PIC MCUsAppNote01/31/20124847KB
AN1491 - Configuring the MCP794XX RTCC FamilyAppNote01/25/2013246KB
AN1496 - Debugging Stand-Alone Real-Time Clock/Calender-based ApplicationsAppNote02/22/2013215KB
AN1519 - Recommended Crystals for Microchip Stand-Alone Real-Time Clock/Calendar DevicesAppNote09/16/2013397KB
AN2027 - Backup Power Sources for Microchip's RTCCs and SRAMsAppNote12/01/2015161KB
TB3116 - Questions and Answers Concerning MCP79XXX Serial RTCCsAppNote08/11/201475KB
Enabling Intelligent Automation Using the MCP7941X I2C RTCCTech Briefs10/21/201074KB
I2C & SPI Real-Time Clock/Calendar Sell SheetBrochures07/21/2014703KB
MCP794xx I2C Real-Time Clock/Calendar BrochureBrochures10/27/2010141KB
MCP794xx Reference Layout Gerber FilesGerber Files05/25/201150KB
AN1355 PIC18F Source CodeSample Code08/21/201261KB
AN1355 PIC24F Source CodeSample Code08/21/2012152KB
Ordering Information
Part NumberLeadsPackage TypeTemp RangePacking1+26+100+1000+5000+
MCP7940N-E/MS8MSOP-40C to +125CTUBE0.840.780.740.690.67
MCP7940N-E/SN8SOIC-40C to +125CTUBE0.800.740.700.660.64
MCP7940N-I/MS8MSOP-40C to +85CTUBE0.780.720.680.640.62
MCP7940N-I/P8PDIP-40C to +85CTUBE0.800.740.700.660.64
MCP7940N-I/SN8SOIC-40C to +85CTUBE0.740.680.650.610.59
MCP7940N-I/ST8TSSOP-40C to +85CTUBE0.780.720.680.640.62
MCP7940NT-E/MS8MSOP-40C to +125CT/R0.840.780.740.690.67
MCP7940NT-E/SN8SOIC-40C to +125CT/R0.800.740.700.660.64
MCP7940NT-I/MNY8TDFN-40C to +85CT/R0.820.760.720.680.66
MCP7940NT-I/MS8MSOP-40C to +85CT/R0.780.720.680.640.62
MCP7940NT-I/SN8SOIC-40C to +85CT/R0.740.680.650.610.59
MCP7940NT-I/ST8TSSOP-40C to +85CT/R0.780.720.680.640.62
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RoHS Information
PartNumberDeviceWeightShippingWeightLeadCountPackageTypePackageWidthSolderCompositionJEDECIndicatorRoHSChinaEFUP
MCP7940N-I/P0.4867000.9000008PDIP.300inMatte Tine3
MCP7940N-I/SN0.0780000.1600008SOIC.150In(3.90mm)Matte Tine3
MCP7940NT-I/SN0.0780000.2303038SOIC.150In(3.90mm)Matte Tine3
MCP7940NT-I/SNV010.0780000.2303038SOIC.150In(3.90mm)Matte Tine3
MCP7940N-E/SN0.0780000.1600008SOIC.150In(3.90mm)Matte Tine3
MCP7940NT-E/SN0.0780000.2303038SOIC.150In(3.90mm)Matte Tine3
MCP7940N-I/ST0.0330000.0900008TSSOP4.4mmMatte Tine3
MCP7940NT-I/ST0.0330000.2156008TSSOP4.4mmMatte Tine3
MCP7940N-I/MS0.0256000.0700008MSOP3x3mmMatte Tine3
MCP7940NT-I/MS0.0256000.2156008MSOP3x3mmMatte Tine3
MCP7940N-E/MS0.0256000.0700008MSOP3x3mmMatte Tine3
MCP7940NT-E/MS0.0256000.2156008MSOP3x3mmMatte Tine3
MCP7940NT-I/MNY0.0143000.2484858TDFN2x3x0.8mmNiPdAue4
MCP7940N Low-Cost I2C Real-Time Clock/Calendar with SRAM and Battery Switchover MCP7940N
MCP7940N Family Silicon Errata MCP7940N
Maxim DS1307 to MCP7940N Migration MCP7940N
Maxim DS1338 to MCP7940N Migration MCP7940N
ST M41T11 to MCP7940N Migration MCP7940N
AN1355 MCP79412
AN1355 Source Code MCP79412
AN1364 MCP79412
AN1364 Source Code MCP79412
AN1365 MCP795W22
AN1413 MCP795W22
AN1413 Source Code MCP795W22
AN1414 MCP79412
Source Code AN1414 MCP79412
AN1491 MCP79412
01491 Source Code MCP79412
AN1491 Source Code MCP79412
AN1496 MCP79412
AN1519 MCP795W22
AN2027 MCP79512
TB3116 MCP795W22
Enabling Intelligent Automation Using the MCP7941X I2C RTCC MCP79412
I2C & SPI Real-Time Clock/Calendar Sell Sheet MCP795W22
MCP794xx I2C Real-Time Clock/Calendar Brochure MCP79412
MCP794xx Reference Layout Gerber Files MCP79412
AN1355 PIC18F Source Code MCP79412
AN1355 PIC24F Source Code MCP79412
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