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. 920-9120
Mfr. Part No.M41T00M6F
HK$13.298
Each (On a Reel of 2500)
units
Calendar D:M:Y:C HH:MM:SS 8B Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +85 °C
RS Stock No. 190-4740
Mfr. Part No.DS1374U-18+
HK$29.201
Each (In a Tube of 50)
units
Binary Counter, Real Time Clock, Trickle Charger - - - Serial-I2C Surface Mount μSOP 10 3.16 x 3.12 x 0.95mm 3.16mm 3.12mm 0.95mm 1.89 V +85 °C
RS Stock No. 165-8028
Mfr. Part No.M41ST87WMX6TR
HK$41.74
Each (On a Reel of 1000)
units
Calendar, Clock DD:MM:YY HH:MM:SS 128B Serial-I2C Surface Mount SOX 28 18.01 x 7.67 x 2.38mm 18.01mm 7.67mm 2.38mm 3.6 V +85 °C
RS Stock No. 192-1626
Mfr. Part No.DS1248Y-70+
HK$334.41
Each
units
SRAM with Phantom Clock YY:MM:DD HH:MM:SS:hh 128 x 8bit Serial Through Hole EDIP 32 44.2 x 18.8 x 10.92mm 44.2mm 18.8mm 10.92mm 5 V +70 °C
RS Stock No. 100-0649
Mfr. Part No.ISL1208IU8Z-T7A
BrandIntersil
HK$39.385
Each (On a Tape of 2)
units
Alarm, Calendar, Clock, SRAM DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount MSOP 8 3.05 x 3.05 x 0.95mm 3.05mm 3.05mm 0.95mm 5.5 V +85 °C
RS Stock No. 920-9010
Mfr. Part No.M41T60Q6F
HK$7.277
Each (On a Reel of 3000)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 8B Serial-I2C Surface Mount QFN 16 3 x 3 x 0.88mm 3mm 3mm 0.88mm 4.4 V +85 °C
RS Stock No. 189-7214
Mfr. Part No.DS1307Z+T&R
HK$17.966
Each (On a Reel of 2500)
units
Battery Backup, Calendar, NV RAM YY:MM:DD HH:MM:SS 56B Serial-I2C Surface Mount SOIC 8 5 x 4 x 1.5mm 5mm 4mm 1.5mm 5.5 V +70 °C
RS Stock No. 827-4628
Mfr. Part No.X1B000172000112
BrandEPSON
HK$31.50
Each
units
Alarm, Calendar, Event Detection and Timestamp, Power Switching, Timer DW:DM:M:Y HH:MM:SS - Serial-I2C Surface Mount SOP 14 10.1 x 5 x 3.15mm 10.1mm 5mm 3.15mm 5.5 V +85 °C
RS Stock No. 798-5258
Mfr. Part No.MCP7940N-I/SN
BrandMicrochip
HK$7.052
Each (In a Pack of 10)
units
Battery Backup, Calendar DW:DM:M:Y HH:MM:SS 64B 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. 690-2851
Mfr. Part No.RV-2123-C2-STD-020
HK$72.20
Each
units
Alarm, Calendar, Timer 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. 189-8379
Mfr. Part No.DS1746-70+
HK$306.26
Each
units
Calendar YY:MM:DD HH:MM:SS 128 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. 540-2710
Mfr. Part No.DS1306+
HK$54.56
Each
units
Alarm, Battery Backup, 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. 190-5136
Mfr. Part No.DS1390U-33+T&R
HK$33.874
Each (In a Pack of 5)
units
Trickle Charger D:D:M:Y - - Serial-SPI Surface Mount μSOP 10 3.16 x 3.12 x 0.95mm 3.16mm 3.12mm 0.95mm 5.5 V +85 °C
RS Stock No. 191-3233
Mfr. Part No.DS1308U-33+
HK$31.721
Each (In a Tube of 50)
units
NV SRAM, Real Time Clock DM:M:DW:Y SS:MM:HH - Serial-I2C Surface Mount μSOP 8 3.1 x 0.65 x 0.95mm 3.1mm 0.65mm 0.95mm 5.5 V +85 °C
RS Stock No. 919-6337
Mfr. Part No.M48T18-100PC1
HK$179.913
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. 786-0742
Mfr. Part No.DS1302N+
HK$38.01
Each (In a Pack of 2)
units
Trickle Charger DM:M:DW:Y SS:MM:HH 31B Serial-3 Wire Through Hole PDIP 8 9.91 x 7.87 x 4.45mm 9.91mm 7.87mm 4.45mm 5.5 V +85 °C
RS Stock No. 786-0758
Mfr. Part No.DS1338C-33#
HK$55.88
Each
units
Clock M:M:DW SS:MM:HH 56B 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. 190-5219
Mfr. Part No.DS3231S#T&R
HK$67.95
Each
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
RS Stock No. 189-7235
Mfr. Part No.DS1390U-3+
HK$31.721
Each (In a Tube of 50)
units
Trickle Charger DD:M:Y SS:MM:HH - Serial-SPI Surface Mount μMAX 10 3.05 x 3.05 x 0.95mm 3.05mm 3.05mm 0.95mm 3.3 V +85 °C
RS Stock No. 732-7374
Mfr. Part No.DS1340U-33+
HK$35.04
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