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, a 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 facilitate the performance of the software functions that are time dependant. They are designed to run on an ultra-low power consumption, often run on a lithium battery source or 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. 774-7403
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
SGD0.98
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. 146-0203
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
SGD0.909
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. 136-0682
Mfr. Part No.DS12887A+
SGD13.959
Each (In a Tube of 14)
units
- - - - - - - - - - - - - -
RS Stock No. 865-2208
Mfr. Part No.PCF8563T/5,518
BrandNXP
SGD1.20
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
SGD1.157
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. 166-1602
Mfr. Part No.PCF8563TS/4,118
BrandNXP
SGD2.399
Each (On a Reel of 2500)
units
Alarm, Battery Backup, Calendar, Watchdog Timer DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount TSSOP 8 3.1 x 3.1 x 0.95mm 3.1mm 3.1mm 0.95mm 5.5 V +85 °C
RS Stock No. 667-6212
Mfr. Part No.Q42724211000200
BrandEPSON
SGD10.14
Each
units
Calendar DW:DM:M:Y HH:MM:SS - Parallel Through Hole PDIP 18 23.1 x 6.3 x 4.2mm 23.1mm 6.3mm 4.2mm 5.5 V +70 °C
RS Stock No. 169-8134
Mfr. Part No.Q42724211000200
BrandEPSON
SGD9.537
Each (In a Tube of 25)
units
Calendar DW:DM:M:Y HH:MM:SS - Parallel Through Hole PDIP 18 23.1 x 6.3 x 4.2mm 23.1mm 6.3mm 4.2mm 5.5 V +70 °C
RS Stock No. 511-103
Mfr. Part No.PCF8563TS/4,118
BrandNXP
SGD2.444
Each (In a Pack of 5)
units
Alarm, Battery Backup, Calendar, Watchdog Timer DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount TSSOP 8 3.1 x 3.1 x 0.95mm 3.1mm 3.1mm 0.95mm 5.5 V +85 °C
RS Stock No. 165-5309
Mfr. Part No.M41T94MQ6F
SGD2.836
Each (On a Reel of 2500)
units
Alarm, Battery Backup, Interrupt, NVRAM, Real Time Clock, Watchdog Timer Binary, D:D:M:Y:C Binary, HH:MM:SS 44B Serial-SPI Surface Mount SOIC 16 10 x 4 x 1.6mm 10mm 4mm 1.6mm 5.5 V +85 °C
RS Stock No. 919-6337
Mfr. Part No.M48T18-100PC1
SGD26.378
Each (In a Tube of 12)
units
Battery Backup, Calendar, Chip Deselect, Switch Over, Write Protection DW:DM:M:Y HH:MM:SS 8192B Parallel Through Hole PCDIP 28 39.88 x 18.34 x 8.89mm 39.88mm 18.34mm 8.89mm 5.5 V +70 °C
RS Stock No. 169-8144
Mfr. Part No.Q41802551000111
BrandEPSON
SGD5.117
Each (On a Reel of 250)
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. 690-2848
Mfr. Part No.RV-3049-C2-STD-025
SGD9.30
Each
units
Alarm, Calendar, Timer DW:DM:M:Y HH:MM:SS 8B Serial-SPI Surface Mount SON 10 5 x 3.2 x 1.2mm 5mm 3.2mm 1.2mm 5.5 V +85 °C
RS Stock No. 165-8028
Mfr. Part No.M41ST87WMX6TR
SGD6.691
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. 165-2097
Mfr. Part No.MCP79511-I/MS
BrandMicrochip
SGD1.98
Each (In a Tube of 100)
units
Calendar D:W:M:Y, LY HH, HS, MM, SS 64B Serial-SPI Surface Mount MSOP 10 3 x 3 x 0.95mm 3mm 3mm 0.95mm 3.6 V +85 °C
RS Stock No. 817-3654
Mfr. Part No.MCP79410T-I/MS
BrandMicrochip
SGD1.24
Each (On a Reel of 2500)
units
Alarm, Battery Backup, Calendar, Clock DW:D:M:Y HH:MM:SS 64B Serial-2 Wire, Serial-I2C Surface Mount MSOP 8 3 x 3 x 0.95mm 3mm 3mm 0.95mm 5.5 V +85 °C
RS Stock No. 714-7298
Mfr. Part No.M48T18-100PC1
SGD28.70
Each
units
Battery Backup, Calendar, Chip Deselect, Switch Over, Write Protection DW:DM:M:Y HH:MM:SS 8192B Parallel Through Hole PCDIP 28 39.88 x 18.34 x 8.89mm 39.88mm 18.34mm 8.89mm 5.5 V +70 °C
RS Stock No. 723-4749
Mfr. Part No.MCP79410-I/MS
BrandMicrochip
SGD1.51
Each (In a Pack of 2)
units
Battery Backup, Calendar, NV SRAM 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. 667-6278
Mfr. Part No.Q41802551000111
BrandEPSON
SGD5.63
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. 907-4732
Mfr. Part No.M41ST87WMX6TR
SGD11.08
Each (In a Pack of 2)
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
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