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PDF DS1990R Data sheet ( Hoja de datos )

Número de pieza DS1990R
Descripción Serial Number IButton
Fabricantes Maxim Integrated Products 
Logotipo Maxim Integrated Products Logotipo



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No Preview Available ! DS1990R Hoja de datos, Descripción, Manual

19-4894; Rev 8/09
www.maxim-ic.com
GENERAL DESCRIPTION
The DS1990R Serial Number iButtonis a rugged
data carrier that serves as an electronic registration
number for automatic identification. Data is
transferred serially through the 1-Wireprotocol,
which requires only a single data lead and a ground
return. Every DS1990R is factory lasered with a
guaranteed unique 64-bit registration number that
allows for absolute traceability. The durable
stainless-steel iButton package is highly resistant to
environmental hazards such as dirt, moisture, and
shock. Its compact coin-shaped profile is self-aligning
with mating receptacles, allowing the DS1990R to be
used easily by human operators. Accessories permit
the DS1990R iButton to be mounted on almost any
object, including containers, pallets, and bags. The
DS1990R is a fully compatible variant of the
DS1990A. In applications where a presence pulse on
contact is critical the DS1990R should be preferred
over the DS1990A.
APPLICATIONS
Access Control
Work-In-Progress Tracking
Tool Management
Inventory Control
MicroCAN
www.DataSheet4U.com
F3 size F5 size
3.10 5.89
0.51
0.51
Branding
16.25
89 01
000000FBC52B
1-Wire
17.35
IO GND IO GND
All dimensions are shown in millimeters.
DS1990R
Serial Number iButton
SPECIAL FEATURES
Upgrade of DS1990A Guarantees Presence
Pulse on Contact
Can be Read in Less Than 5ms
Operating Range: 2.8V to 6.0V, -40°C to +85°C
COMMON iButton FEATURES
Unique Factory-Lasered 64-Bit Registration
Number Assures Error-Free Device Selection
and Absolute Traceability Because No Two Parts
are Alike
Built-In Multidrop Controller for 1-Wire Net
Digital Identification by Momentary Contact
Data can be Accessed While Affixed to Object
Economically Communicates to Bus Master with
a Single Digital Signal at 16.3kbps
Button Shape is Self-Aligning 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
PART
TEMP RANGE PIN-PACKAGE
DS1990R-F5# -40°C to +85°C F5 iButton
DS1990R-F3# -40°C to +85°C F3 iButton
#Denotes a RoHS-compliant device that may include lead(Pb) that is
exempt under the RoHS requirements.
EXAMPLES OF ACCESSORIES
PART
DS9096P
DS9101
DS9093RA
DS9093A
DS9092
DESCRIPTION
Self-Stick Adhesive Pad
Multipurpose Clip
Mounting Lock Ring
Snap-In Fob
iButton Probe
iButton and 1-Wire are registered trademarks of Maxim Integrated Products, Inc.
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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DS1990R pdf
Figure 4. HARDWARE CONFIGURATION
SIMPLE BUS MASTER
RX
VPUP
RPUP
TX RX = Receive
TX = Transmit
Open Drain
Port Pin
DS1990R: Serial Number iButton
DS1990R 1-Wire PORT
DATA
RX
TX
100
MOSFET
DS2480B BUS MASTER
HOST CPU
Serial serial in
Port serial out
VDD VPP
POL 1-W
RXD NC
TXD GND
DS2480B
+5V
To 1-Wire data
INITIALIZATION
All transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequence consists of a
reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the slave(s). The presence
pulse lets the bus master know that the DS1990R is on the bus and is ready to operate. For more details, see the
1-Wire Signaling section.
1-Wire ROM FUNCTION COMMANDS
wwwO.DnactaeSthheeet4bUu.csommaster has detected a presence, it can issue one of ROM function commands that the DS1990R
supports. All ROM function commands are 8 bits long. A list of these commands follows (see flowchart in Figure 5).
READ ROM [33h] or [0Fh]
This command allows the bus master to read the DS1990R’s 8-bit family code, unique 48-bit serial number, and 8-
bit CRC. This command can only be used if there is a single slave device on the bus. If more than one slave is
present on the bus, a data collision will occur when all slaves try to transmit at the same time (open drain will pro-
duce a wired-AND result). The resultant family code and 48-bit serial number will result in a mismatch of the CRC.
SEARCH ROM [F0h]
When a system is initially brought up, the bus master might not know the number of devices on the 1-Wire bus or
their registration numbers. By taking advantage of the wired-AND property of the bus, the master can use a
process of elimination to identify the registration numbers of all slave devices. For each bit of the registration
number, starting with the least significant bit, the bus master issues a triplet of time slots. On the first slot, each
slave device participating in the search outputs the true value of its registration number bit. On the second slot,
each slave device participating in the search outputs the complemented value of its registration number bit. On the
third slot, the master writes the true value of the bit to be selected. All slave devices that do not match the bit
written by the master stop participating in the search. If both of the read bits are zero, the master knows that slave
devices exist with both states of the bit. By choosing which state to write, the bus master branches in the ROM
code tree. After one complete pass, the bus master knows the registration number of a single device. Additional
passes identify the registration numbers of the remaining devices. Refer to App Note 187: 1-Wire Search Algorithm
for a detailed discussion, including an example.
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