19-4734 Rev 7/09 DS1971 256-Bit EEPROM iButton SPECIAL FEATURES COMMON iButton FEATURES 256-bit Electrically Erasable Programmable Unique, factory-lasered and tested 64-bit Read Only Memory (EEPROM) registration number (8-bit family code + 48- communicates with the economy of one bit serial number + 8-bit CRC tester) assures signal plus ground absolute traceability because no two parts are EEPROM organized as one 256-bit page alike 64-bit one-time programmable application Multidrop controller for MicroLAN register is automatically write-protected after Digital identification and information by programming momentary contact Reduces control, address, data, power, and Chip-based data carrier compactly stores programming signals to a single data pin information 8-bit family code specifies DS1971 Data can be accessed while affixed to object communications requirements to reader Economically communicates to bus master Reads and writes over a wide voltage range with a single digital signal at 16.3kbps of 2.8V to 6.0V from -40C to +85C Standard 16mm diameter and 1-Wire protocol ensure compatibility with iButton family F3 MicroCan Button shape is selfaligning 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 ORDERING INFORMATION DS1971-F3+ F3 MicroCan F5 MicroCan DS1971-F5+ F5 MicroCan +Denotes a lead(Pb)-free/RoHS-compliant package. EXAMPLES OF ACCESSORIES DS9096P Self-Stick Adhesive Pad DS9101 Multi-Purpose Clip DS9093RA Mounting Lock Ring DS9093F Snap-in Fob DS9092 iButton Probe iButton and 1-Wire are registered trademarks of Maxim Integrated Products, Inc. 1 of 4 DS1971 iButton DESCRIPTION The DS1971 256-bit EEPROM iButton is a rugged read/write data carrier that identifies and stores relevant information about the product or person to which it is attached. This information can be accessed with minimal hardware: for example, a single port pin of a microcontroller. The DS1971 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 (14H) plus 256 bits of EEPROM. The power to program and read the DS1971 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 48-bit serial number that is factory- lasered into each DS1971 provides a guaranteed unique identity which allows for absolute traceability. The durable MicroCan package is highly resistant to harsh environments such as dirt, moisture, and shock. Its compact button-shaped profile is self-aligning with cup-shaped receptacles, allowing the DS1971 to be used easily by human operators or automatic equipment. Accessories permit the DS1971 to be mounted on printed circuit boards, plastic key fobs, photo-ID badges, ID bracelets, and many other objects. Applications include work-in-progress tracking, electronic travelers, access control and storage of calibration constants. OVERVIEW The block diagram in Figure 1 shows the relationships between the major control and memory sections of the DS1971. The DS1971 has four main data components: 1) 64-bit lasered ROM, 2) 256-bit EEPROM data memory with scratchpad, 3) 64-bit one-time programmable application register with scratchpad, and 4) 8-bit status memory. The bus master must first provide one of the ROM Function Commands before the memory functions become accessible. All data is read and written least significant bit first. The DS1971 contains the same memory chip as the DS2430A. For a full description of the logical behavior, refer to the DS2430A data sheet. 2 of 4