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DS1904
RTC iButton


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Data Sheet
FULL DATA SHEET (PDF, 216kB)
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Description
The DS1904 RTC iButton® is a rugged real-time clock module that can be accessed with minimal hardware. Data is transferred serially by the 1-Wire® protocol, which requires only a single data lead and a ground return. The DS1904 contains a unique 64-bit factory-lasered ROM and a real-time clock/calendar implemented as a binary counter. The durable MicroCan® package is highly resistant to environmental hazards such as dirt, moisture, and shock. Accessories permit the DS1904 to be mounted on almost any surface including printed circuit boards and plastic key fobs. The DS1904 adds functions such as calendar, time and date stamp, stopwatch, hour meter, interval timer, and logbook to any type of electronic device or embedded application that uses a microcontroller.

Key Features
  • Real-time clock/calendar in binary format
  • Uses the same binary time/date representation as the DS1994 but with 1 second resolution
  • Clock accuracy is better than ± 2 minutes per month at +25°C
  • Operating temperature range from -40°C to +70°C
  • Over 10 years of operation
  • Unique, factory-lasered and tested 64-bit registration number (8-bit family code + 48-bit serial number + 8-bit CRC tester) assures absolute traceability because no two parts are alike
  • Multidrop controller for MicroLAN
  • Digital identification and information by momentary contact
  • Chip-based data carrier compactly stores information
  • Data can be accessed while affixed to object
  • Economically communicates to host with a single digital signal at 16.3kbits per second
  • Standard 16mm diameter and 1-Wire protocol ensure compatibility with iButton device family
  • Button shape is self-aligning with cup-shaped probes
  • Durable stainless steel case engraved with registration number withstands harsh environments
  • Easily affixed with self-stick adhesive backing, latched by its flange, or locked with a ring pressed onto its rim
  • Presence detector acknowledges when reader first applies voltage
  • Meets UL#913 (4th Edit.); Intrinsically Safe Apparatus, approved under Entity Concept for use in Class I, Division 1, Group A, B, C and D locations (application pending)
  • Underwriters Laboratories (UL®) Recognized

Key Specifications:   iButton Products
Part Number Overview Memory Type Memory Size UniqueWare Real-Time Clock Price**
DS1904 
RTC iButton
ROM Only 64 bits No Yes $3.08 @ 1k
See All iButton Products (25)
Notes:
**This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Diagram

Application Notes
  • Application Note 27: Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products - DS1904
  • Application Note 126: 1-Wire Communication Through Software - DS1904
  • Application Note 148: Guidelines for Reliable Long Line 1-Wire® Networks - DS1904
  • Application Note 155: 1-Wire® Software Resource Guide Device Description - DS1904
  • Application Note 159: Software Methods to Achieve Robust 1-Wire® Communication in iButton® Applications - DS1904
  • Application Note 187: 1-Wire Search Algorithm - DS1904
  • Application Note 192: Using the DS2480B Serial 1-Wire Line Driver - DS1904
  • Application Note 244: Advanced 1-Wire Network Driver - DS1904
  • Application Note 1100: White Paper 5: Using 1-Wire APIs for Data Sheet Commands - DS1904
  • Application Note 3808: What Is an iButton? - DS1904

    Evaluation Kits
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    Reliability Reports
  • Request Reliability Report for:
  • Underwriters Laboratories (UL®) Recognized

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-1 of 1

    DS1904 Free
    Sample
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    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    DS1904L-F5#  
    0 pin;

    Use pkgcode/variation: IB#5CB*
    Special - See Data Sheet RoHS/Lead-Free: RoHS Qualified
    Materials Analysis

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    2003-11-12
    This page last modified: 2008-04-02



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