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General Description

The DS1990R serial number iButton

is a rugged data

carrier that serves as an electronic registration number

for automatic identification. Data is transferred serially

through the 1-Wire

protocol, which requires only a sin-

gle data lead and a ground return. Every DS1990R is

factory lasered with a guaranteed unique 64-bit regis-

tration number that allows for absolute traceability. The

durable stainless-steel iButton package is highly resis-

tant 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

enable 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

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 i

Button Features

♦ Unique Factory-Lasered 64-Bit Registration

Number Ensures 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

DS1990R

Serial Number i

Button

________________________________________________________________

Maxim Integrated Products

Pin Configurations

Ordering Information

19-4894; Rev 4; 8/10

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

PART TEMP RANGE PIN-PACKAGE

DS1990R-F5# -40°C to +85°C F5 i

Button

DS1990R-F3# -40°C to +85°C F3 iButton

Examples of Accessories

PART ACCESSORY

DS9096P Self-Stick Adhesive Pad

DS9101 Multipurpose Clip

DS9093RA Mounting Lock Ring

DS9093A Snap-In Fob

DS9092 iButton Probe

16.25mm

5.89mm

0.51mm

3.10mm

0.51mm

17.35mm

BRANDING

F5 SIZE

GND

IOIO

F3 SIZE

89 01

000000FBC52B

1-Wire

iButton and 1-Wire are registered trademarks of Maxim

Integrated Products, Inc.

Denotes a RoHS-compliant device that may include lead(Pb)

that is exempt under the RoHS requirements.

Summary of content (10 pages)

PAGE 1
9-4894; Rev 4; 8/10 Serial Number iButton The DS1990R serial number iButton® is a rugged data carrier that serves as an electronic registration number for automatic identification. Data is transferred serially through the 1-Wire® protocol, 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.
PAGE 2
DS1990R Serial Number iButton ABSOLUTE MAXIMUM RATINGS IO Voltage Range to GND .....................................-0.5V to +6.0V IO Sink Current....................................................................20mA Junction Temperature ......................................................+125°C Storage Temperature Range .............................-55°C to +125°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
PAGE 3
Serial Number iButton Note 12: Note 13: Note 14: Note 15: The voltage on IO must be less than or equal to VILMAX whenever the master drives the line low. VIH is a function of the internal supply voltage. 30nC per 72 time slots at 5.0V pullup voltage with a 5kΩ pullup resistor and tSLOT ≤ 120µs. The reset low time (tRSTL) should be restricted to a maximum of 960µs to allow interrupt signaling. A longer duration could mask or conceal interrupt pulses if this device is used in parallel with a DS1994.
PAGE 4
DS1990R Serial Number iButton 1-Wire Bus System 64-Bit Lasered ROM Each DS1990R contains 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 for details. 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.
PAGE 5
Serial Number iButton for more than 120µs, one or more devices on the bus may be reset. The 1-Wire bus has only a single line by definition; it is important that each device on the bus be able to drive it at the appropriate time. To facilitate this, each device attached to the 1-Wire bus must have open-drain or three-state outputs. The 1-Wire port of the DS1990R is open drain with an internal circuit equivalent to that shown in Figure 4.
PAGE 6
Serial Number iButton DS1990R 1-Wire ROM Function Commands Once the bus master has detected a presence pulse, it can issue one of the ROM function commands the DS1990R supports. All ROM function commands are 8 bits long. A list of these commands follows. (See Figure 5 for a flowchart.
PAGE 7
Serial Number iButton detect a presence pulse, the master must test the logical state of the 1-Wire line at tMSP. The DS1990R requires strict protocols to ensure data integrity. The protocol consists of four types of signaling on one line: reset sequence with reset pulse and presence pulse, write-zero, write-one, and read-data. Except for the presence pulse, the bus master initiates all these signals. To get from idle to active, the voltage on the 1-Wire line needs to fall from VPUP to below VILMAX.
PAGE 8
DS1990R Serial Number iButton WRITE-ONE TIME SLOT tW1L VPUP VIHMASTER VIHMIN VILMAX 0V ε tF tSLOT RESISTOR MASTER WRITE-ZERO TIME SLOT tW0L VPUP VIHMASTER VIHMIN VILMAX 0V ε tF tREC tSLOT RESISTOR MASTER READ-DATA TIME SLOT tMSR tRL VPUP VIHMASTER VIHMIN MASTER SAMPLING WINDOW VILMAX 0V δ tF tREC tSLOT RESISTOR MASTER DS1990R Figure 7.
PAGE 9
Serial Number iButton The sum of tRL + δ (rise time) on one side and the internal timing generator of the DS1990R on the other side define the master sampling window (t MSRMIN to tMSRMAX) in which the master must perform a read from the data line. For most reliable communication, t RL should be as short as permissible and the master should read close to but no later than tMSRMAX. After reading from the data line, the master must wait until tSLOT is expired.
PAGE 10
DS1990R Serial Number iButton Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 5/05 Initial release — 1 8/06 Reworded the UL#913 bullet to “Designed to meet...