1Kb Add-Only Memory

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The DS2502 1Kb Add-Only Memory identifies and stores relevant information about the product to which it is associated. This lot- or product-specific information can be accessed with minimal interface—for example, a single port pin of a microcontroller. The DS2502 consists of a factory-lasered registration number that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit Family Code (09h) plus 1Kb of EPROM which is user-programmable. The power to program and read the DS2502 is derived entirely from the 1-Wire® communication line.

Data is transferred serially via the 1-Wire protocol which requires only a single data lead and a ground return. The entire device can be programmed and then write-protected if desired. Alternatively, the part may be programmed multiple times with new data being appended to, but not overwriting, existing data with each subsequent programming of the device. Note: Individual bits can be changed only from a logical 1 to a logical 0, never from a logical 0 to a logical 1. A provision is also included for indicating that a certain page or pages of data are no longer valid and have been replaced with new or updated data that is now residing at an alternate page address. This page address redirection allows software to patch data and enhance the flexibility of the device as a stand-alone database. The 48-bit serial number that is factory-lasered into each DS2502 provides a guaranteed unique identity which allows for absolute traceability. The familiar TO-92 or SOIC or TSOC packages provide a compact enclosure that allows standard assembly equipment to handle the device easily for attachment to printed circuit boards or wiring. Typical applications include storage of calibration constants, maintenance records, asset tracking, product revision status, and access codes.
DS2502: Block Diagram DS2502: Block Diagram Enlarge+

Key Features

  • Easily Add Traceability and Relevant Information to Any Individual System
    • 1k-Bit EPROM with Page-Level Write Protection and Guaranteed Unique 64-Bit ROM ID Chip for Absolute Traceability
    • 1024 Bits Electrically Programmable Read Only Memory (EPROM)
    • Unique, Factory-Lasered and Tested 64-Bit Registration Number (8-Bit Family Code + 48-Bit Serial Number + 8-Bit CRC Tester)
    • EPROM Partitioned into Four 256-Bit Pages for Randomly Accessing Packetized Data
    • Each Memory Page Can Be Permanently Write- Protected to Prevent Tampering
    • Device is an Add Only Memory Where Additional Data Can Be Programmed into EPROM Without Disturbing Existing Data
    • Architecture Allows Software to Patch Data by Superseding an Old Page in Favor of a Newly Programmed Page
    • 8-Bit Family Code Specifies DS2502 Communications Requirements to Reader
  • Minimalist 1-Wire Interface Lowers Cost and Interface Complexity
    • Reduces Control, Address, Data, Power, and Programming Signals to a Single Data Pin
    • Directly Connects to a Single Port Pin of a Microprocessor and Communicates at up to 16.3kb Per Second
    • Built-In Multidrop Controller Ensures Compatibility with Other 1-Wire Net Products o Presence Pulse Acknowledges When the Reader First Applies Voltage
    • Low Cost TO-92, SFN, or 8-Pin SO, SOT-23 (3 Pin), TSOC and WLP Surface Mount Package
  • Wide Voltage and Temperature Operating Ranges Provide Robust System Performance
    • Reads Over Voltage Range of 2.8V to 6.0V at -40°C to +85°C
    • Zero Standby Power Required
    • Programs at 11.5V to 12.0V from -40°C to +50°C

See parametric specs for Memory (EPROM, EEPROM, ROM, NV SRAM) (47)

Part NumberMemory TypeMemory SizeBus TypeVSUPPLY
(min)(max)(See Notes)
DS2502 EPROM1K x 11-Wire2.86
SOIC (N)/8
$1.09 @1k

Pricing 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 and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

DS2502EVKIT: Evaluation Kit for the DS2502
DS9481R-3C7: USB-to-1-Wire/iButton 3.3V Adapter
DS9120: Socket Boards for Evaluating 1-Wire Devices
DS9120P: Socket Boards for Evaluating 1-Wire Devices
DS9120Q: Socket Boards for Evaluating 1-Wire Devices
Product Reliability Reports: DS2502.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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