{"id":7042,"date":"2026-06-23T02:21:29","date_gmt":"2026-06-23T02:21:29","guid":{"rendered":"https:\/\/materialparts.com\/ds1340u-33\/"},"modified":"2026-06-23T02:21:29","modified_gmt":"2026-06-23T02:21:29","slug":"ds1340u-33","status":"publish","type":"post","link":"https:\/\/materialparts.com\/ar\/ds1340u-33\/","title":{"rendered":"DS1340U-33+"},"content":{"rendered":"

\u0646\u0638\u0631\u0629 \u0639\u0627\u0645\u0629 \u0639\u0644\u0649 \u0627\u0644\u0645\u0646\u062a\u062c<\/h2>\n

The DS1340U-33+ from Analog Devices (Maxim Integrated) is an I2C real-time clock with trickle charger in an SOIC-8 package. The -33 suffix denotes the 3.3V version with programmable trickle charger for 3.3V backup batteries. It features 400kHz I2C fast mode, 400nA backup current, and automatic leap year compensation.<\/p>\n

\u0627\u0644\u0645\u0648\u0627\u0635\u0641\u0627\u062a \u0627\u0644\u0631\u0626\u064a\u0633\u064a\u0629<\/h2>\n\n\n\n\n\n\n\n\n\n\n
\u0627\u0644\u0648\u0627\u062c\u0647\u0629<\/td>\nI2C (400kHz Fast Mode)<\/td>\n<\/tr>\n
Clock Functions<\/td>\nSeconds through year with auto leap year<\/td>\n<\/tr>\n
\u062c\u0647\u062f \u0627\u0644\u0625\u0645\u062f\u0627\u062f<\/td>\n1.3V ~ 3.63V (Main)<\/td>\n<\/tr>\n
Backup Battery Voltage<\/td>\n1.3V ~ 3.63V<\/td>\n<\/tr>\n
Backup Current<\/td>\n400nA (Typical) @ VBAT=3.0V<\/td>\n<\/tr>\n
Trickle Charger<\/td>\nProgrammable, 3.3V battery support<\/td>\n<\/tr>\n
Write Protect<\/td>\nYes (Clock registers)<\/td>\n<\/tr>\n
\u0627\u0644\u062d\u0632\u0645\u0629<\/td>\nSOIC-8 (4.90 x 3.90mm)<\/td>\n<\/tr>\n
\u062f\u0631\u062c\u0629 \u062d\u0631\u0627\u0631\u0629 \u0627\u0644\u062a\u0634\u063a\u064a\u0644<\/td>\n-40\u00b0C ~ +85\u00b0C<\/td>\n<\/tr>\n<\/table>\n

\u0627\u0644\u0645\u064a\u0632\u0627\u062a<\/h2>\n
    \n
  • Complete RTC with BCD-coded calendar (seconds to year)<\/li>\n
  • Automatic leap year compensation through 2100<\/li>\n
  • I2C 400kHz fast mode interface<\/li>\n
  • Programmable trickle charger for backup battery maintenance<\/li>\n
  • Ultra-low 400nA backup current extends battery life<\/li>\n
  • Clock register write protection prevents corruption during power transitions<\/li>\n
  • 3.3V version (-33 suffix) with lead-free packaging (+ suffix)<\/li>\n
  • On-chip 32.768kHz oscillator requires only external crystal<\/li>\n<\/ul>\n

    \u0627\u0644\u062a\u0637\u0628\u064a\u0642\u0627\u062a<\/h2>\n
      \n
    • Embedded system timekeeping<\/li>\n
    • Power metering timestamping<\/li>\n
    • Data logging time stamps<\/li>\n
    • Industrial controller scheduling<\/li>\n
    • Point-of-sale transaction timing<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The DS1340U-33+ from Analog Devices (Maxim Integrated) is an I2C real-time clock with trickle charger in an SOIC-8 package. The -33 suffix denotes the 3.3V version with programmable trickle charger for 3.3V backup batteries. It features 400kHz I2C fast mode, 400nA backup current, and automatic leap year compensation. Key Specifications Interface I2C (400kHz […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,55],"tags":[],"chip_brand":[165],"class_list":["post-7042","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-transistors","chip_brand-adi"],"acf":{"brief_explanation":"I2C RTC with trickle charger, 3.3V version, 400nA backup, auto leap year, SOIC-8","date_code":"","package_case":"SOIC-8 (4.90 x 3.90 x 1.50 mm)","in_stock":7079,"datasheet":"https:\/\/www.analog.com\/media\/en\/technical-documentation\/data-sheets\/DS1340.pdf","price":"$1.50 @ 1ku","product_introduction":"The DS1340U-33+ from Analog Devices (formerly Maxim Integrated\/Dallas Semiconductor) is a low-cost, low-power I2C real-time clock with an integrated programmable trickle charger. The -33 suffix indicates the 3.3V version that supports backup batteries in the 3.0V to 3.63V range. The device provides a full BCD-coded clock calendar with seconds, minutes, hours, day, date, month, and year, including automatic leap year compensation valid through 2100. The I2C interface operates at up to 400kHz (fast mode) for efficient communication with host microcontrollers. The ultra-low 400nA backup current at VBAT=3.0V ensures long battery life in timekeeping mode. The programmable trickle charger can maintain a rechargeable backup battery (such as a supercap or ML2020 lithium coin cell) from the main supply. Write protection circuitry prevents clock register corruption during power-up and power-down transitions.","working_principle":"The DS1340U-33+ operates as an I2C slave device with the RTC function implemented in a dedicated timekeeping domain powered from either VCC or VBAT, whichever is higher. When VCC is above the VBAT switchover threshold, the device operates from VCC and the trickle charger (if enabled) charges the backup battery. When VCC drops below VBAT, the internal power-switching circuit automatically connects the timekeeping domain to VBAT, maintaining clock operation with only 400nA current draw. The 32.768kHz crystal oscillator runs continuously in the timekeeping domain. The clock counters increment the BCD time registers every second based on the crystal oscillator. The I2C interface allows the host to read and write the time registers; however, write protection prevents writes when the supply voltage is below the valid operating range. The trickle charger is configured through a register bit and consists of a diode and resistor in series between VCC and VBAT, with selectable diode count and resistor value.","pin_description":"
      Pin<\/th>Name<\/th>Function<\/th><\/tr>
      1<\/td>SDA<\/td>I2C serial data (open-drain)<\/td><\/tr>
      2<\/td>SCL<\/td>I2C serial clock (open-drain)<\/td><\/tr>
      3<\/td>X1<\/td>32.768kHz crystal input<\/td><\/tr>
      4<\/td>GND<\/td>Ground<\/td><\/tr>
      5<\/td>X2<\/td>32.768kHz crystal output<\/td><\/tr>
      6<\/td>VBAT<\/td>Backup battery input (1.3V-3.63V)<\/td><\/tr>
      7<\/td>CLK<\/td>Frequency output (open-drain, optional)<\/td><\/tr>
      8<\/td>VCC<\/td>Main supply voltage (1.3V-3.63V)<\/td><\/tr><\/table>","application_scenarios":"
      • Smart Meter Timestamping<\/b>: 400nA backup current ensures clock accuracy during power outages; trickle charger maintains supercap backup for 10+ year meter lifetime<\/li>
      • Industrial Data Logger<\/b>: Automatic leap year compensation provides accurate timestamps for years of unattended operation; I2C interface shares bus with sensors<\/li>
      • POS Transaction Terminal<\/b>: 3.3V operation matches modern MCU supply; write protection prevents timestamp corruption during power cycling<\/li>
      • Embedded Linux HWclock<\/b>: I2C fast mode enables quick time reads during boot; programmable trickle charger maintains ML battery from 3.3V rail<\/li><\/ul>","alternative_models":"
        Model<\/th>Manufacturer<\/th>Key Difference<\/th><\/tr>
        DS1340U-5+<\/td>ADI<\/td>5V version of DS1340<\/td><\/tr>
        DS3231SN#<\/td>ADI<\/td>TCXO RTC, +\/-2ppm, no crystal needed, SOIC-16<\/td><\/tr>
        MCP7940N-I\/P<\/td>Microchip<\/td>I2C RTC, 64-byte SRAM, DIP-8<\/td><\/tr>
        PCF8563BS<\/td>NXP<\/td>I2C RTC, TSSOP-8, 250nA backup<\/td><\/tr>
        RV-3028-C7<\/td>Micro Crystal<\/td>I2C, +\/-1ppm, 40nA backup, QFN<\/td><\/tr><\/table>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/7042","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/comments?post=7042"}],"version-history":[{"count":0,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/7042\/revisions"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/media?parent=7042"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/categories?post=7042"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/tags?post=7042"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/chip_brand?post=7042"}],"curies":[{"name":"\u062f\u0628\u0644\u064a\u0648 \u0628\u064a","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}