DS2502: 1Kb Add-Only Memory

• 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 16.3kbits 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
• 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

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.