iButton and 1-Wire are registered trademarks of Maxim Integrated Products, Inc.
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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.
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DS1971
DS1971 BLOCK DIAGRAM
Figure 1
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DS1971
REVISION HISTORY
REVISION
DATE
071508
7/09
DESCRIPTION
Updated the
F3 MicroCan
and
F5 MicroCan
face brands with the latest
per PCN H020201.
Conversion to lead(Pb)-free; removal of bullet “Designed to meet
UL#913 (4th Edit.)….”
PAGES
CHANGED
1
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Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim
reserves the right to change the circuitry and specifications without notice at any time.
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