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. 133-781
Mfr. Part No.DS12887+
BrandMaxim
TWD452
Each
units
Alarm, Battery Backup, Calendar, Power Fail Binary, DW:DM:M:Y Binary, HH:MM:SS 114B Multiplexed Through Hole EDIP 24 34.04 x 18.8 x 9.4mm 34.04mm 18.8mm 9.4mm 5.5 V +70 °C
RS Stock No. 146-1112
Mfr. Part No.DS12887+
BrandMaxim
TWD400
Each (In a Tube of 14)
units
Alarm, Battery Backup, Calendar, Power Fail Binary, DW:DM:M:Y Binary, HH:MM:SS 114B Multiplexed Through Hole EDIP 24 34.04 x 18.8 x 9.4mm 34.04mm 18.8mm 9.4mm 5.5 V +70 °C
RS Stock No. 714-7298
Mfr. Part No.M48T18-100PC1
TWD593
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. 919-6337
Mfr. Part No.M48T18-100PC1
TWD522
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. 803-2204
Mfr. Part No.MCP795W22-I/SL
BrandMicrochip
TWD66
Each (In a Pack of 5)
units
Calendar DW:M:Y:LY HH:MM:SS:HSS 64B Serial Surface Mount SOIC 14 8.65 x 3.9 x 1.25mm 8.65mm 3.9mm 1.25mm 3.6 V +85 °C
RS Stock No. 165-1954
Mfr. Part No.MCP795W22-I/SL
BrandMicrochip
TWD73
Each (In a Tube of 57)
units
Calendar DW:M:Y:LY HH:MM:SS:HSS 64B Serial Surface Mount SOIC 14 8.65 x 3.9 x 1.25mm 8.65mm 3.9mm 1.25mm 3.6 V +85 °C
RS Stock No. 165-9062
Mfr. Part No.DS1307+
BrandMaxim
TWD128
Each (In a Tube of 50)
units
Alarm, Battery Backup, Calendar, Power Fail DW:DM:M:Y HH:MM:SS 56B Serial-I2C Through Hole PDIP 8 9.91 x 7.87 x 4.45mm 9.91mm 7.87mm 4.45mm 5.5 V +70 °C
RS Stock No. 540-2726
Mfr. Part No.DS1307+
BrandMaxim
TWD150
Each
units
Alarm, Battery Backup, Calendar, Power Fail DW:DM:M:Y HH:MM:SS 56B Serial-I2C Through Hole PDIP 8 9.91 x 7.87 x 4.45mm 9.91mm 7.87mm 4.45mm 5.5 V +70 °C
RS Stock No. 797-9509
Mfr. Part No.DS1643P-100+
BrandMaxim
TWD844
Each
units
Timekeeping RAM YY:MM:DD HH:MM:SS - Parallel Surface Mount Power Cap 34 25.27 x 23.62 x 0.81mm 25.27mm 23.62mm 0.81mm 5.5 V +70 °C
RS Stock No. 660-6360
Mfr. Part No.BQ4822YMA-70
TWD1,440
Each
units
Alarm, Battery Backup, Calendar, Chip Deselect, Power Fail, Watchdog Timer, Write Protection DW:DM:M:Y HH:MM:SS:hh 8192B Parallel Through Hole PDIP 28 37.72 x 18.42 x 9.4mm 37.72mm 18.42mm 9.4mm 5.5 V +70 °C
RS Stock No. 714-0855
Mfr. Part No.M41T00SM6F
TWD70
Each
units
- DW:DM:M:Y HH:MM:SS 8B Serial-2 Wire, Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.25mm 5mm 4mm 1.25mm 5.5 V +85 °C
RS Stock No. 778-1484
Mfr. Part No.DS3231MZ+
BrandMaxim
TWD259
Each
units
Battery Backup, Calendar Binary HH:MM:SS - Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +85 °C
RS Stock No. 139-600
Mfr. Part No.DS12C887+
BrandMaxim
TWD438
Each
units
Alarm Binary, DW:DM:M:Y Binary, HH:MM:SS 113B Multiplexed Through Hole EDIP 24 34.04 x 18.29 x 9.4mm 34.04mm 18.29mm 9.4mm 5.5 V +70 °C
RS Stock No. 165-9743
Mfr. Part No.DS3231MZ+
BrandMaxim
TWD282
Each (In a Tube of 100)
units
Battery Backup, Calendar Binary HH:MM:SS - Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +85 °C
RS Stock No. 168-6813
Mfr. Part No.M41T00SM6F
TWD68
Each (On a Reel of 2500)
units
- DW:DM:M:Y HH:MM:SS 8B Serial-2 Wire, Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.25mm 5mm 4mm 1.25mm 5.5 V +85 °C
RS Stock No. 146-1117
Mfr. Part No.DS12C887+
BrandMaxim
TWD388
Each (In a Tube of 14)
units
Alarm Binary, DW:DM:M:Y Binary, HH:MM:SS 113B Multiplexed Through Hole EDIP 24 34.04 x 18.29 x 9.4mm 34.04mm 18.29mm 9.4mm 5.5 V +70 °C
RS Stock No. 704-4688
Mfr. Part No.ISL12020MIRZ
TWD229
Each
units
Alarm, Battery Backup, Calendar, Switch Over DW:DM:M:Y HH:MM:SS 128B Serial-I2C Surface Mount DFN 20 5.5 x 4 x 1.3mm 5.5mm 4mm 1.3mm 5.5 V +85 °C
RS Stock No. 540-2704
Mfr. Part No.DS1302+
BrandMaxim
TWD113
Each
units
Alarm, Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 31B Serial Through Hole PDIP 8 9.91 x 7.87 x 4.45mm 9.91mm 7.87mm 4.45mm 5.5 V +70 °C
RS Stock No. 923-7497
Mfr. Part No.DS1302ZN+T&R
BrandMaxim
TWD90
Each (On a Reel of 2500)
units
Battery Backup, Calendar, NV RAM YY:MM:DD HH:MM:SS 31B Serial-3 Wire Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +85 °C
RS Stock No. 923-1499
Mfr. Part No.ISL12020MIRZ
TWD179
Each (In a Tube of 53)
units
Alarm, Battery Backup, Calendar, Switch Over DW:DM:M:Y HH:MM:SS 128B Serial-I2C Surface Mount DFN 20 5.5 x 4 x 1.3mm 5.5mm 4mm 1.3mm 5.5 V +85 °C