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. 877-2781
Mfr. Part No.M41T83SQA6F
€2.74
Each (In a Pack of 5)
units
Real Time Clock DW:DM:M:Y HH:MM:SS:hh 32B Serial-2 Wire, Serial-I2C Surface Mount QFN 16 4.1 x 4.1 x 0.95mm 4.1mm 4.1mm 0.95mm 5.5 V +85 °C
RS Stock No. 920-9001
Mfr. Part No.M48T35Y-70PC1
€19.961
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. 165-5486
Mfr. Part No.M41T83SQA6F
€1.449
Each (On a Reel of 1000)
units
Real Time Clock DW:DM:M:Y HH:MM:SS:hh 32B Serial-2 Wire, Serial-I2C Surface Mount QFN 16 4.1 x 4.1 x 0.95mm 4.1mm 4.1mm 0.95mm 5.5 V +85 °C
RS Stock No. 624-8466
Mfr. Part No.M48T35Y-70PC1
€21.65
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. 188-9366
Mfr. Part No.M41ST85WMX6TR
€5.65
Each
units
Alarm, Battery Backup, Calendar, Watchdog Timer Binary, D:D:M:Y:C - 64bit - Surface Mount SOX 28 18.01 x 7.67 x 2.39mm 18.01mm 7.67mm 2.39mm 3.6 V +85 °C
RS Stock No. 189-8414
Mfr. Part No.DS1306EN+
€5.065
Each (In a Pack of 2)
units
Battery Backup, Calendar, NV RAM DW:DM:M:Y HH:MM:SS 96B Serial-SPI Surface Mount TSSOP 20 6.6 x 4.5 x 0.95mm 6.6mm 4.5mm 0.95mm 5.5 V +85 °C
RS Stock No. 196-9065
Mfr. Part No.ISL12022IBZ
€3.82
Each (In a Pack of 2)
units
- DW:DM:M:Y HH:MM:SS - - - SOIC 8 - - - - - -
RS Stock No. 171-1647
Mfr. Part No.RV-2123-C2-TA-010
€5.64
Each (On a Tape of 100)
units
Calendar DW:DM:M:Y HH:MM:SS - 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. 828-9977
Mfr. Part No.M48T12-70PC1
€13.95
Each
units
Timekeeper SRAM D:M:Y HH:MM:SS 16kbit - Through Hole PCDIP 24 34.8 x 18.34 x 8.89mm 34.8mm 18.34mm 8.89mm 5.5 V +70 °C
RS Stock No. 189-7205
Mfr. Part No.DS1305+
€4.362
Each (In a Tube of 25)
units
Alarm, Calendar DW:DM:M:Y HH:MM:SS 96B Serial-SPI Through Hole PDIP 16 19.43 x 7.87 x 4.45mm 19.43mm 7.87mm 4.45mm 5.5 V +70 °C
RS Stock No. 190-5152
Mfr. Part No.DS1347T+T&R
€12.61
1 Pack of 5
Pack(s)
Alarm, Real Time Clock, SRAM DM:M:Y:C SS:MM:HH - - Surface Mount TDFN-EP 8 3.1 x 3.1 x 0.8mm 3.1mm 3.1mm 0.8mm 5.5 V +85 °C
RS Stock No. 920-8991
Mfr. Part No.M48T58Y-70PC1
€13.553
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. 189-7227
Mfr. Part No.DS1339U-33+
€2.785
Each (In a Tube of 50)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount μSOP 8 3.1 x 3.1 x 0.95mm 3.1mm 3.1mm 0.95mm 5.5 V +85 °C
RS Stock No. 192-1232
Mfr. Part No.DS1305N+
€4.449
Each (In a Tube of 25)
units
Alarm, Trickle Charger YY:MM:DD HH:MM:SS 96B Serial-SPI Through Hole PDIP 16 19.43 x 7.87 x 4.45mm 19.43mm 7.87mm 4.45mm 5.5 V +85 °C
RS Stock No. 191-3543
Mfr. Part No.DS3231M+
€6.23
Each
units
Real Time Clock D:D:M:Y SS:MM:HH - Serial-I2C Surface Mount SO 16 10.5 x 7.6 x 2.35mm 10.5mm 7.6mm 2.35mm 5.5 V +85 °C
RS Stock No. 686-5036
Mfr. Part No.M48T58-70PC1
€15.65
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. 168-6880
Mfr. Part No.M41T11MH6F
€2.464
Each (On a Reel of 936)
units
Calendar, Chip Deselect, Switch Over DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount SOH 28 18.49 x 8.89 x 2.69mm 18.49mm 8.89mm 2.69mm 5.5 V +85 °C
RS Stock No. 196-9066
Mfr. Part No.ISL12057IUZ
€1.753
Each (In a Tube of 50)
units
- DW:DM:M:Y HH:MM:SS - - - MSOP 8 - - - - - -
RS Stock No. 823-7954
Mfr. Part No.MCP79511-I/MS
BrandMicrochip
€1.018
Each (In a Pack of 5)
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. 189-7221
Mfr. Part No.DS1337U+
€1.762
Each (In a Tube of 50)
units
Real Time Clock D:D:M:Y:C SS:MM:HH - Serial-I2C Surface Mount μSOP 8 3.1 x 3.1 x 0.95mm 3.1mm 3.1mm 0.95mm 5.5 V +85 °C