The DS1972 is a 1024-bit, 1-Wire® EEPROM chip organized
as four memory pages of 256 bits each in a rugged iButton® package. Data is written to an 8-byte scratchpad, verified, and then copied to the EEPROM memory. As a special feature, the four memory pages can individually be write protected or put in EPROMemulation mode, where bits can only be changed from a 1 to a 0 state. The DS1972 communicates over the single-conductor 1-Wire bus. The communication follows the standard 1-Wire protocol. Each device has its own unalterable and unique 64-bit ROM registration number that is factory lasered into the device. The registration number is used to address the device in a multidrop,
1-Wire net environment.
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 factorylasered into each DS1972 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 DS1972 to be used easily by human operators or automatic equipment. Accessories permit the DS1972 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.
Special Features
- 1024 Bits of EEPROM Memory Partitioned Into Four Pages of 256 Bits
- Individual Memory Pages Can Be PermanentlyWrite Protected or Put in EPROM-Emulation Mode (“Write to 0”)
- Switchpoint Hysteresis and Filtering to Optimize Performance in the Presence of Noise
- IEC 1000-4-2 Level 4 ESD Protection (±8kV Contact, ±15kV Air, Typical)
- Reads and Writes Over a Wide Voltage Range from 2.8V to 5.25V from -40°C to +85°C
- Communicates to Host with a Single Digital Signal at 15.4kbps or 125kbps Using 1-Wire Protocol
Common iButton Features
- 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 bus master with a single digital signal at 16.3kbps
- Standard 16mm diameter and 1-Wire® protocol ensure compatibility with iButton family
- Button shape is self-aligning with cupshaped 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
- Designed to meet UL#913 (4th Edit.); Intrinsically Safe Apparatus, Under Entity Concept for use in Class I, Division 1, Group A, B, C and D Locations, contact Dallas Semiconductor for certification schedule
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