The ISL1208 device is a low power real time clock with timing and crystal compensation, clock/calendar, power fail indicator, periodic or polled alarm, intelligent battery backup switching and battery-backed user SRAM. The oscillator uses an external, low-cost 32. 768kHz crystal. The real time clock tracks time with separate registers for hours, minutes, and seconds. The device has calendar registers for date, month, year and day of the week. The calendar is accurate through 2099, with automatic leap year correction.


  • Real Time Clock/Calendar
  • Tracks Time in Hours, Minutes, and Seconds
  • Day of the Week, Day, Month, and Year
  • 15 Selectable Frequency Outputs
  • Single Alarm
  • Settable to the Second, Minute, Hour, Day of the Week, Day, or Month
  • Single Event or Pulse Interrupt Mode
  • Automatic Backup to Battery or Super Capacitor
  • Power Failure Detection
  • On-Chip Oscillator Compensation
  • 2 Bytes Battery-Backed User SRAM
  • I2C Interface
  • 400kHz Data Transfer Rate
  • 400nA Battery Supply Current
  • Same Pin Out as ST M41Txx and Maxim DS13xx Devices
  • Small Package Options
  • 8 Ld MSOP and SOIC Packages
  • 8 Ld TDFN Package
  • Pb-Free Available (RoHS Compliant)


  • Utility Meters
  • HVAC Equipment
  • Audio/Video Components
  • Set-Top Box/Television
  • Modems
  • Network Routers, Hubs, Switches, Bridges
  • Cellular Infrastructure Equipment
  • Fixed Broadband Wireless Equipment
  • Pagers/PDA
  • POS Equipment
  • Test Meters/Fixtures
  • Office Automation (Copiers, Fax)
  • Home Appliances
  • Computer Products

tuneProduct Options

Part Number Part Status Pkg. Type Carrier Type MOQ Buy Sample
Active SOICN Tube 100
Active SOICN Reel 250
Active SOICN Reel 1000
Active TDFN Tube 100
Active TDFN Reel 1000
Active MSOP Tube 80
Active MSOP Reel 250
Active MSOP Reel 1000


Title language Type Format File Size Date
Datasheets & Errata
star ISL1208 Datasheet Datasheet PDF 1.58 MB
User Guides & Manuals
Real Time Clock USB Evaluation Board User Guide Manual - Development Tools PDF 815 KB
AN1373: Low Cost RTC Family User Guide Manual - Development Tools PDF 443 KB
Real Time Clock USB Eval Board User Guide Manual - Development Tools PDF 913 KB
Application Notes & White Papers
AN1549: Addressing Power Issues in Real Time Clock Applications Application Note PDF 302 KB
AN1342: Using 60Hz Power Line Frequency as an Accurate Real Time Clock Timebase Application Note PDF 329 KB
PA14042 - Minimum Line Quantity Change Product Advisory PDF 363 KB
PCN12085 - 8l, 14l, 16l SOIC w/ Gold Bond Wire @ ATP as Alternate Assembly Site Product Change Notice PDF 152 KB
PCN12084 - Manufacturing Site Change for the Listed Intersil Products - Carsem (CAS) Ipoh Malaysia Product Change Notice PDF 135 KB
Analog ICs Brochure 日本語 Brochure PDF 4.20 MB
PIN19028 - Q3 Cy 19 Price Increase Notice Price Increase Notice PDF 208 KB
IDT Clock Generation Overview Overview PDF 1.83 MB
TB481: Using ISL12058 as a Low Cost Alternative to ISL1208 and ISL12082 Other PDF 243 KB
TB467: Transitioning from the DS1339 to the ISL1208 RTC Device Other PDF 266 KB
TB460: Replacing the x1226, x1227 or x1228 RTC with the ISL12026, ISL12026A, ISL12027 or ISL12028 Other PDF 302 KB
TB464: Transitioning from the M41T00 to the ISL1208 RTC Device Other PDF 264 KB
TB456: Trickle Charging Lithium Batteries with the ISL1208 and ISL1209 RTC Devices Other PDF 232 KB


Title language Type Format File Size Date
RTC WIN8 Preinstallation Procedure Software & Tools - Other PDF 846 KB
Real Time Clock (RTC) Evaluation Installer for Windows 8 Library EXE 7.85 MB
Real Time Clock (RTC) Evaluation Installer for Windows 2000 Library EXE 1.62 MB
Real Time Clock (RTC) Evaluation Installer for Windows XP / Windows 7 Library EXE 3.02 MB

memoryBoards & Kits

Part Number Title Type Company
ISL120x-RTC-USB-Evaluation-System ISL120x Real Time Clock USB Evaluation System Evaluation Renesas

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