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 A provision is also included for indicating that a certain page or pages of data are no longer valid and have been replaced with new or updated data that is now residing at an alternate page address.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.
1024 bits Electrically Programmable Read Only Memory (EPROM) communicates with the economy of one signal plus ground
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
Built-in multidrop controller ensures compatibility with other MicroLAN products
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
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 16.3 kbits per second
8-bit family code specifies DS2502 communications requirements to reader
Presence detector acknowledges when the reader first applies voltage
Low cost TO-92 or 8-pin SO, SOT-23 (3-pin), TSOC and flip chip surface mount package
Reads over a wide voltage range of 2.8V to 6.0V from -40°C to +85°C; programs at 11.5V to 12.0V from -40°C to +50°C
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