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. 865-2208
Mfr. Part No.PCF8563T/5,518
BrandNXP
MYR3.996
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
MYR3.85
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. 624-8466
Mfr. Part No.M48T35Y-70PC1
MYR102.58
Each
units
Battery Backup, Calendar, Chip Deselect, Switch Over, Write Protection DW:DM:M:Y HH:MM:SS 32768B 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. 146-0203
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
MYR2.509
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. 920-9001
Mfr. Part No.M48T35Y-70PC1
MYR94.64
Each (In a Tube of 12)
units
Battery Backup, Calendar, Chip Deselect, Switch Over, Write Protection DW:DM:M:Y HH:MM:SS 32768B 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. 774-7403
Mfr. Part No.MCP7940M-I/P
BrandMicrochip
MYR2.723
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. 912-6943
Mfr. Part No.MCP7940M-I/SN
BrandMicrochip
MYR2.183
Each (In a Tube of 100)
units
Calendar, NV SRAM 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. 761-7627
Mfr. Part No.MCP7940M-I/SN
BrandMicrochip
MYR2.468
Each (In a Pack of 5)
units
Calendar, NV SRAM 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. 624-8438
Mfr. Part No.M41T62Q6F
MYR7.81
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. 920-9007
Mfr. Part No.M41T62Q6F
MYR3.713
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. 823-3712
Mfr. Part No.MCP7940N-I/ST
BrandMicrochip
MYR3.315
Each (In a Pack of 10)
units
Calendar DW:D:M:Y HH:MM:SS 64B Serial-I2C Surface Mount TSSOP 8 4.5 x 3.1 x 1.05mm 4.5mm 3.1mm 1.05mm 5.5 V +85 °C
RS Stock No. 825-1076
Mfr. Part No.MCP79510-I/MS
BrandMicrochip
MYR4.70
Each (In a Pack of 5)
units
Calendar DW:M:Y:LY HH:MM:SS:HSS 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. 732-7333
Mfr. Part No.DS1307ZN+
MYR16.19
Each
units
Calendar DW:DM:M:Y HH:MM:SS 56B Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +85 °C
RS Stock No. 726-3949
Mfr. Part No.MCP79410-I/SN
BrandMicrochip
MYR3.826
Each (In a Pack of 5)
units
Battery Backup, Calendar, NV SRAM 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. 817-3658
Mfr. Part No.MCP79410T-I/SN
BrandMicrochip
MYR3.77
Each (On a Reel of 3300)
units
Alarm, Battery Backup, Calendar, Clock DW:D:M:Y HH:MM:SS 64B Serial-2 Wire, 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. 145-9048
Mfr. Part No.MCP7940N-I/ST
BrandMicrochip
MYR2.917
Each (In a Tube of 100)
units
Calendar DW:D:M:Y HH:MM:SS 64B Serial-I2C Surface Mount TSSOP 8 4.5 x 3.1 x 1.05mm 4.5mm 3.1mm 1.05mm 5.5 V +85 °C
RS Stock No. 732-7374
Mfr. Part No.DS1340U-33+
MYR15.62
Each
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount μSOP 8 3.05 x 3.05 x 0.95mm 3.05mm 3.05mm 0.95mm 5.5 V +85 °C
RS Stock No. 165-2099
Mfr. Part No.MCP79510-I/MS
BrandMicrochip
MYR4.172
Each (In a Tube of 100)
units
Calendar DW:M:Y:LY HH:MM:SS:HSS 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. 889-5121
Mfr. Part No.MCP79410-I/SN
BrandMicrochip
MYR3.946
Each (In a Tube of 100)
units
Battery Backup, Calendar, Clock, NV Timekeeping SRAM 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. 817-3667
Mfr. Part No.MCP79410T-I/ST
BrandMicrochip
MYR3.949
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 TSSOP 8 3.1 x 4.5 x 1.05mm 3.1mm 4.5mm 1.05mm 5.5 V +85 °C