Real Time Clocks

What is a Real Time Clock?

A Real Time Clock (RTC) is a computer clock which is usually in the form of an integrated circuit. They have been designed to keep track of time, in real time - hence the product name. A Real Time Clock is usually an integral part of the computer motherboard. More often than not, an RTC will also include a calendar and an alarm

How do Real Time Clocks work?

The memory on the clocks system stores system descriptions and set up values such as "Current Time Value". The information that is held in the RTC is read with a microprocessor, commonly over a serial interface which facilitates the performance of the software functions that are time dependant.

Designed to run on ultra-low power consumption, RTCs often run on a lithium battery source but can also run on normal power. This power source allows them to continue running and generating real time when a system is down. The newer models of RTC use super-capacitors as a source of power that can be recharged and soldered to the board. Some Real Time Clocks feature synchronisation to an external signal, such as a compensated power line frequency. It allows the device to provide an accurate result without having an on-board temperature compensation scheme.

RTC Time Values

  • Year
  • Month
  • Date
  • Hours
  • Minutes
  • Seconds

...
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Description Price Functions Date Format Time Format User RAM Bus Type Mounting Type Package Type Pin Count Dimensions Length Width Height Maximum Operating Supply Voltage Maximum Operating Temperature
RS Stock No. 920-9007
Mfr. Part No.M41T62Q6F
PHP65.227
Each (On a Reel of 3000)
units
Alarm, Battery Backup, Calendar, Watchdog Timer DW:DM:M:Y HH:MM:SS:hh 16B Serial-I2C Surface Mount QFN 16 3 x 3 x 0.88mm 3mm 3mm 0.88mm 4.4 V +85 °C
RS Stock No. 624-8438
Mfr. Part No.M41T62Q6F
PHP119.166
Each (In a Pack of 5)
units
Alarm, Battery Backup, Calendar, Watchdog Timer DW:DM:M:Y HH:MM:SS:hh 16B Serial-I2C Surface Mount QFN 16 3 x 3 x 0.88mm 3mm 3mm 0.88mm 4.4 V +85 °C
RS Stock No. 165-2125
Mfr. Part No.MCP7940N-I/P
BrandMicrochip
PHP43.068
Each (In a Tube of 60)
units
Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Through Hole PDIP 8 10.16 x 7.11 x 4.95mm 10.16mm 7.11mm 4.95mm 5.5 V +85 °C
RS Stock No. 810-3933
Mfr. Part No.MCP7940N-I/P
BrandMicrochip
PHP45.083
Each (In a Pack of 10)
units
Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Through Hole PDIP 8 10.16 x 7.11 x 4.95mm 10.16mm 7.11mm 4.95mm 5.5 V +85 °C
RS Stock No. 146-0203
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
PHP34.759
Each (In a Tube of 60)
units
Alarm, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Through Hole PDIP 8 10.16 x 7.11 x 4.95mm 10.16mm 7.11mm 4.95mm 5.5 V +85 °C
RS Stock No. 774-7403
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
PHP36.991
Each (In a Bag of 10)
units
Alarm, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Through Hole PDIP 8 10.16 x 7.11 x 4.95mm 10.16mm 7.11mm 4.95mm 5.5 V +85 °C
RS Stock No. 809-1420
Mfr. Part No.M41T81M6F
PHP136.342
Each (In a Pack of 5)
units
Alarm Binary HH:MM:SS:hh 20B Serial Surface Mount SOIC 8 5 x 4 x 1.25mm 5mm 4mm 1.25mm 5.5 V +85 °C
RS Stock No. 798-5258
Mfr. Part No.MCP7940N-I/SN
BrandMicrochip
PHP40.462
Each (In a Pack of 10)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount SOIC 8 4.9 x 3.9 x 1.5mm 4.9mm 3.9mm 1.5mm 5.5 V +85 °C
RS Stock No. 165-1998
Mfr. Part No.MCP7940N-I/MS
BrandMicrochip
PHP42.192
Each (In a Tube of 100)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount MSOP 8 3 x 3 x 0.95mm 3mm 3mm 0.95mm 5.5 V +85 °C
RS Stock No. 865-2208
Mfr. Part No.PCF8563T/5,518
BrandNXP
PHP73.397
Each (In a Pack of 10)
units
Calendar, Clock YY:MM:DD:dd HH:MM:SS - Serial-2 Wire, Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.45mm 5mm 4mm 1.45mm 5.5 V +85 °C
RS Stock No. 124-2362
Mfr. Part No.PCF8563T/5,518
BrandNXP
PHP58.065
Each (On a Reel of 2500)
units
Calendar, Clock YY:MM:DD:dd HH:MM:SS - Serial-2 Wire, Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.45mm 5mm 4mm 1.45mm 5.5 V +85 °C
RS Stock No. 912-2774
Mfr. Part No.MCP7940N-I/SN
BrandMicrochip
PHP40.105
Each (In a Tube of 100)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount SOIC 8 4.9 x 3.9 x 1.5mm 4.9mm 3.9mm 1.5mm 5.5 V +85 °C
RS Stock No. 667-6278
Mfr. Part No.Q41802551000111
BrandEPSON
PHP212.86
Each
units
Alarm, Calendar, Timer - - - Serial-I2C Surface Mount SOP 14 5 x 10.1 x 3.2mm 5mm 10.1mm 3.2mm 5.5 V +85 °C
RS Stock No. 165-8028
Mfr. Part No.M41ST87WMX6TR
PHP280.323
Each (On a Reel of 1000)
units
Calendar, Clock DD:MM:YY HH:MM:SS 128B Serial-I2C Surface Mount SOX 28 18.01 x 7.67 x 2.38mm 18.01mm 7.67mm 2.38mm 3.6 V +85 °C
RS Stock No. 667-6230
Mfr. Part No.Q41454351000111
BrandEPSON
PHP206.28
Each
units
Calendar, Timer - - - Serial Surface Mount SOP 14 5 x 10.1 x 3.2mm 5mm 10.1mm 3.2mm 5.5 V +85 °C
RS Stock No. 168-8043
Mfr. Part No.M41ST87WSS6F
PHP271.656
Each (On a Reel of 1350)
units
Calendar D:D:M:Y:C HH:MM:SS:HSS 128B Serial Surface Mount SSOP 20 7.5 x 5.6 x 1.85mm 7.5mm 5.6mm 1.85mm 3.6 V +85 °C
RS Stock No. 102-3553
Mfr. Part No.M41T81M6F
PHP78.862
Each (On a Reel of 2500)
units
Alarm Binary HH:MM:SS:hh 20B Serial Surface Mount SOIC 8 5 x 4 x 1.25mm 5mm 4mm 1.25mm 5.5 V +85 °C
RS Stock No. 103-1580
Mfr. Part No.M41T56M6F
PHP87.624
Each (On a Reel of 2500)
units
Calendar, Chip Deselect, Switch Over DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount SOIC 8 4.9 x 3.9 x 1.25mm 4.9mm 3.9mm 1.25mm 5.5 V +85 °C
RS Stock No. 146-0213
Mfr. Part No.MCP79412-I/SN
BrandMicrochip
PHP53.173
Each (In a Tube of 100)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount SOIC 8 4.9 x 3.9 x 1.5mm 4.9mm 3.9mm 1.5mm 5.5 V +85 °C
RS Stock No. 169-8137
Mfr. Part No.Q41454351000111
BrandEPSON
PHP185.034
Each (On a Reel of 250)
units
Calendar, Timer - - - Serial Surface Mount SOP 14 5 x 10.1 x 3.2mm 5mm 10.1mm 3.2mm 5.5 V +85 °C