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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 667-6230
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. 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. 169-8137
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. 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. 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. 177-0305
Mfr. Part No.MCP7940N-E/SN
BrandMicrochip
HK$6.091
Each (In a Tube of 100)
units
- D:M:Y, DW HH:MM:SS - Serial-I2C Surface Mount SOIC 8 4.9 x 3.9 x 1.5mm 4.9mm 3.9mm 1.5mm 5.5 V +125 °C
RS Stock No. 205-3455
Mfr. Part No.X1B000242000112
BrandEpson
HK$13.954
Each (In a Pack of 5)
units
Real Time Clock - - 128bit - - SOP-14 14 - - - - - -
RS Stock No. 165-9386
Mfr. Part No.DS1340C-33#
HK$44.867
Each (In a Tube of 46)
units
Trickle Charger DD:M:Y SS:MM:HH 7B Serial-I2C Surface Mount SOIC 16 18.1 x 7.6 x 2.35mm 18.1mm 7.6mm 2.35mm 5.5 V +85 °C
RS Stock No. 165-3406
Mfr. Part No.MCP7940MT-I/MNY
BrandMicrochip
HK$5.109
Each (On a Reel of 3300)
units
Calendar, NV SRAM DW:DM:M:Y HH:MM:SS 64B Serial-I2C Surface Mount TDFN 8 2 x 3 x 0.75mm 2mm 3mm 0.75mm 5.5 V +85 °C
RS Stock No. 177-0307
Mfr. Part No.MCP79412-I/MS
BrandMicrochip
HK$7.849
Each (In a Tube of 100)
units
- D:M:Y, DW HH:MM:SS - Serial-I2C Surface Mount MSOP 8 3 x 3 x 0.95mm 3mm 3mm 0.95mm 5.5 V +85 °C
RS Stock No. 162-6913
Mfr. Part No.BQ4802LYPW
HK$54.291
Each (In a Tube of 50)
units
Alarm, Battery Backup, Calendar, NV SRAM DW:DM:M:Y HH:MM:SS 16B Parallel Surface Mount TSSOP 28 9.7 x 4.4 x 1.15mm 9.7mm 4.4mm 1.15mm 3.6 V +70 °C