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. 169-8144
Mfr. Part No.Q41802551000111
BrandEPSON
HK$25.771
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. 686-5030
Mfr. Part No.M48T58Y-70PC1
HK$166.09
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. 667-6278
Mfr. Part No.Q41802551000111
BrandEPSON
HK$32.35
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. 920-8991
Mfr. Part No.M48T58Y-70PC1
HK$159.126
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. 124-2362
Mfr. Part No.PCF8563T/5,518
BrandNXP
HK$6.993
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. 729-3243
Mfr. Part No.RV-2123-C2-TA-010
HK$80.44
Each
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. 667-6212
Mfr. Part No.Q42724211000200
BrandEPSON
HK$61.00
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. 904-7512
Mfr. Part No.X1B000311000112
BrandEPSON
HK$44.46
Each
units
Clock - SS:HH 32bit Serial-I2C Surface Mount - 10 3.2 x 2.5 x 1mm 3.2mm 2.5mm 1mm 5.5 V +85 °C
RS Stock No. 169-8222
Mfr. Part No.X1B000311000112
BrandEPSON
HK$33.71
Each (On a Tape of 20)
units
Clock - SS:HH 32bit Serial-I2C Surface Mount - 10 3.2 x 2.5 x 1mm 3.2mm 2.5mm 1mm 5.5 V +85 °C
RS Stock No. 169-8134
Mfr. Part No.Q42724211000200
BrandEPSON
HK$46.477
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. 171-1647
Mfr. Part No.RV-2123-C2-TA-010
HK$59.937
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. 865-2208
Mfr. Part No.PCF8563T/5,518
BrandNXP
HK$7.491
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. 169-8137
Mfr. Part No.Q41454351000111
BrandEPSON
HK$22.622
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
RS Stock No. 667-6230
Mfr. Part No.Q41454351000111
BrandEPSON
HK$31.74
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. 540-2704
Mfr. Part No.DS1302+
HK$35.67
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. 190-4754
Mfr. Part No.DS3234SN#T&R
HK$41.015
Each (On a Reel of 1000)
units
Crystal, Real Time Clock, SRAM D:D:M:Y SS:MM:HH 256B Serial-SPI Surface Mount SO 20 13 x 7.6 x 2.35mm 13mm 7.6mm 2.35mm 5.5 V +85 °C
RS Stock No. 923-7778
Mfr. Part No.DS1747-70+
HK$323.379
Each (In a Tube of 10)
units
Calendar YY:MM:DD HH:MM:SS 512 x 8bit Parallel Through Hole EDIP 32 44.2 x 18.8 x 10.92mm 44.2mm 18.8mm 10.92mm 0.8 V, 5.3 V +70 °C
RS Stock No. 169-8141
Mfr. Part No.Q41856471000111
BrandEPSON
HK$26.212
Each (On a Reel of 250)
units
Alarm, Calendar, Timer DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount VSOJ 20 - 7mm 5.4mm - 5.5 V +85 °C
RS Stock No. 189-8536
Mfr. Part No.DS1374U-33+
HK$33.052
Each (In a Pack of 5)
units
Battery Backup, NV RAM Binary SS 3B Serial-I2C Surface Mount μSOP 10 3.05 x 3.05 x 0.95mm 3.05mm 3.05mm 0.95mm 5.5 V +85 °C
RS Stock No. 190-4749
Mfr. Part No.DS3231S#T&R
HK$42.387
Each (On a Reel of 1000)
units
Real Time Clock DM:M:DW: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 +70 °C