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Número de pieza | DS1991 | |
Descripción | MultiKey iButton | |
Fabricantes | Dallas Semiconductor | |
Logotipo | ||
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SPECIAL FEATURES
§ 1,152-bit secure read/write, nonvolatile
memory
www.DataSh§eet4SUe.ccoumre memory cannot be deciphered
without matching 64-bit password
§ Memory is partitioned into 3 blocks of 384
bits each
§ 64-bit password and ID fields for each
memory block
§ 512-bit scratchpad ensures data transfer
integrity
§ Operating temperature range: -40°C to
+70°C
§ Over 10 years of data retention
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 16.3k bits per
second
§ Standard 16 mm diameter and 1-Wire
protocol ensure compatibility with iButton
family
§ Button shape is self-aligning with cup-
shaped probes
§ Durable stainless steel case engraved with
registration number withstands harsh
environments
DS1991
MultiKey iButtonTM
§ 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
F5 MICROCANTM
5.89
0.36
0.51
c 1993 16.25
YYWW REGISTERED RR
21 02
000000FBC52B
17.35
DATA
GROUND
All dimensions shown in millimeters
ORDERING INFORMATION
DS1991L-F5
F5 MicroCan
EXAMPLES OF ACCESSORIES
DS9096P
Self-Stick Adhesive Pad
DS9101
Multi-Purpose Clip
DS9093RA
Mounting Lock Ring
DS9093F
Snap-In Fob
DS9092
iButton Probe
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082099
1 page DS1991
Write Password [5AH]
The Write Password command is used to enter the ID and password of the selected subkey. This
command will erase all of the data stored in the secure area as well as overwriting the ID and password
fields with the new data. The DS1991 has a built-in check to ensure that the proper subkey was selected.
The sequence begins by reading the ID field of the selected subkey; the ID of the subkey to be changed is
then written into the part. If the IDs do not match, the sequence is terminated. Otherwise, the subkey
contents are erased and 64 bits of new ID data are written followed by a new 64-bit password. The
command sequence is shown in Figure 5, 2nd page, right column.
MEMORY FUNCTIONS FLOW CHART Figure 5
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5 of 14
5 Page DS1991
INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 10
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RESISTOR
MASTER
DS1991
480 µs ≤ tRSTL < ∞ *
480 µs ≤ tRSTH < ∞(includes recovery time)
15 µs ≤ tPDH < 60 µs
60 µs ≤ tPDL < 240 µs
∗ In order not to mask interrupt signaling by other devices on the 1-Wire bus, tRSTL + tR should always
be less than 960 µs.
READ/WRITE TIME SLOTS
The definitions of write and read time slots are illustrated in Figure 11. All time slots are initiated by the
master driving the data line low. The falling edge of the data line synchronizes the DS1991 to the master
by triggering a delay circuit in the DS1991. During write time slots, the delay circuit determines when the
DS1991 will sample the data line. For a read data time slot, if a “0” is to be transmitted, the delay circuit
determines how long the DS1991 will hold the data line low overriding the 1 generated by the master. If
the data bit is a “1”, the iButton will leave the read data time slot unchanged.
READ/WRITE TIMING DIAGRAM Figure 11
Write-One Time Slot
RESISTOR
MASTER
60 µs ≤ tSLOT < 120 µs
1 µs ≤ tLOW1 < 15 µs
1 µs ≤ tREC < ∞
11 of 14
11 Page |
Páginas | Total 14 Páginas | |
PDF Descargar | [ Datasheet DS1991.PDF ] |
Número de pieza | Descripción | Fabricantes |
DS1990A | Serial Number iButton | Dallas Semiconductor |
DS1990R | Serial Number IButton | Maxim Integrated Products |
DS1991 | MultiKey iButton | Dallas Semiconductor |
DS1992 | (DS1992 / DS1993) 1kbit/4kbit Memory iButtonTM DS1994 4-kbit Plus Time Memory iButtonTM | Dallas Semiconductor |
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