Memory iButtonTM. DS1992 Datasheet

DS1992 Datasheet PDF, Equivalent

Part Number



(DS1992 / DS1993) 1kbit/4kbit Memory iButtonTM DS1994 4-kbit Plus Time Memory iButtonTM


Dallas Semiconductor

Total Page 17 Pages
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DS1992 Datasheet
§ 4096 bits of Read/Write Nonvolatile
Memory (DS1993)
§ 1024 bits of Read/Write Nonvolatile
Memory (DS1992)
§ 256-bit Scratchpad Ensures Integrity of Data
§ Memory Partitioned into 256-bit Pages for
Packetizing Data
§ Data Integrity Assured with Strict
Read/Write Protocols
§ Operating Temperature Range from -40°C to
§ Over 10 years of data retention
§ 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
§ Data Can be Accessed While Affixed to
§ Economically Communicates to Bus Master
with a Single Digital Signal at 16.3kbps
§ Standard 16mm Diameter and 1-Wire®
Protocol Ensure Compatibility with iButton®
§ Button Shape is Self-Aligning with Cup-
Shaped Probes
§ Durable Stainless Steel Case Engraved with
Registration Number Withstands Harsh
1kb/4kb Memory iButton
§ 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
§ Meets UL#913 (4th Edit.); Intrinsically Safe
Apparatus, Approved under Entity Concept
for use in Class I, Division 1, Group A, B, C
and D Locations
0.36 0.51
© 1993
DD 06
All dimensions shown in millimeters.
F5 MicroCan
F5 MicroCan
DS9096P Self-Stick Adhesive Pad
DS9101 Multipurpose Clip
DS9093RA Mounting Lock Ring
DS9093F Snap-In Fob
DS9092 iButton Probe
1-Wire and iButton are registered trademarks of Dallas Semiconductor.
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DS1992 Datasheet
The DS1992/DS1993 memory iButtons (hereafter referred to as DS199_) are rugged read/write data
carriers that act as a localized database, easily accessible with minimal hardware. The nonvolatile
memory and optional timekeeping capability offer a simple solution to storing and retrieving vital
information pertaining to the object to which the iButton is attached. Data is transferred serially through
the 1-Wire protocol that requires only a single data lead and a ground return.
The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written to
the scratchpad where it can be read back. After the data has been verified, a copy scratchpad command
transfers the data to memory. This process ensures data integrity when modifying the memory. A 48-bit
serial number is factory lasered into each DS199_ to provide a guaranteed unique identity that allows for
absolute traceability. The durable MicroCan package is highly resistant to environmental hazards such as
dirt, moisture, and shock. Its compact coin-shaped profile is self-aligning with mating receptacles,
www.DataShaelleot4wU.icnogm the DS199_ to be easily used by human operators. Accessories permit the DS199_ to be
mounted on almost any surface including plastic key fobs, photo–ID badges, and PC boards.
Applications include access control, work-in-progress tracking, electronic travelers, storage of calibration
constants, and debit tokens.
The DS199_ have three main data components: 1) 64-bit lasered ROM, 2) 256-bit scratchpad, and 3)
1024-bit (DS1992) or 4096-bit (DS1993) SRAM. All data is read and written least significant bit first.
The memory functions are not available until the ROM function protocol has been established. This
protocol is described in the ROM functions flow chart (Figure 9). The master must first provide one of
four ROM function commands: 1) read ROM, 2) match ROM, 3) search ROM, or 4) skip ROM. After a
ROM function sequence has been successfully executed, the memory functions are accessible and the
master can then provide any one of the four memory function commands (Figure 6).
The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry steals power whenever
the data input is high. The data line provides sufficient power as long as the specified timing and voltage
requirements are met. The advantages of parasite power are two-fold: 1) by parasiting off this input,
lithium is conserved, and 2) if the lithium is exhausted for any reason, the ROM can still be read
Each DS199_ contain a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code.
The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. (See Figure 2.)
The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and XOR gates
as shown in Figure 3. The polynomial is X8 + X5 + X4 + 1. Additional information about the Dallas 1-Wire
Cyclic Redundancy Check is available in the Book of DS19xx iButton Standards. The shift register bits
are initialized to zero. Then starting with the least significant bit of the family code, 1 bit at a time is
shifted in. After the 8th bit of the family code has been entered, then the serial number is entered. After
the 48th bit of the serial number has been entered, the shift register contains the CRC value. Shifting in
the 8 bits of CRC should return the shift register to all zeros.
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Features Datasheet pdf DS1992/DS1993 1kb/4kb Memory iButton www SPECIAL FEATURES 4096 bit s of Read/Write Nonvolatile Memory (DS1 993) § 1024 bits of Read/Write Nonvola tile Memory (DS1992) § 256-bit Scratch pad Ensures Integrity of Data www.DataS Transfer § Memory Partition ed into 256-bit Pages for Packetizing D ata § Data Integrity Assured with Stri ct Read/Write Protocols § Operating Te mperature Range from -40°C to +70°C Over 10 years of data retention § § § Easily Affixed with Self-Stick Adhesive Backing, Latched by its Flang e, or Locked with a Ring Pressed onto i ts Rim Presence Detector Acknowledges W hen Reader First Applies Voltage Meets UL#913 (4th Edit.); Intrinsically Safe Apparatus, Approved under Entity Concep t for use in Class I, Division 1, Group A, B, C and D Locations F5 MICROCAN 5 .89 0.36 0.51 © 1993 COMMON iButton F EATURES § Unique, Factory-Lasered and Tested 64-bit Registration Number (8-bi t Family Code + 48-bit Serial Number + 8-bit CRC Tester) Assures Absolute Tra.
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