Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)64 kBit

AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The DS1990A 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 DS1990A 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 DS1990A

to be used easily by human operators. Accessories

enable the DS1990A iButton to be mounted on almost

any object, including containers, pallets, and bags.

Applications

Access Control

Work-In-Progress Tracking

Tool Management

Inventory Control

Features

♦ 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 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

Serial Number i

Button

Pin Configurations

Ordering Information

Rev: 10/08

PART TEMP RANGE PIN-PACKAGE

DS1990A-F5+ -40°C to +85°C F5 i

Button

DS1990A-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 lead(Pb)-free/RoHS-compliant package.

DS1990A

Ordering Information

Summary of content (10 pages)

PAGE 1
DS1990A LE AVAILAB Serial Number iButton General Description The DS1990A 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 DS1990A is factory lasered with a guaranteed unique 64-bit registration number that allows for absolute traceability.
PAGE 2
DS1990A 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
DS1990A Serial Number iButton Note 8: Note 9: Note 10: Note 11: 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.
PAGE 4
DS1990A Serial Number iButton 1-Wire Bus System 64-Bit Lasered ROM Each DS1990A 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
DS1990A Serial Number iButton Hardware Configuration 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 DS1990A is open drain with an internal circuit equivalent to that shown in Figure 4.
PAGE 6
DS1990A Serial Number iButton 1-Wire ROM Function Commands Once the bus master has detected a presence, it can issue one of the ROM function commands the DS1990A supports. All ROM function commands are 8 bits long. A list of these commands follows. (See Figure 5 for a flowchart.
PAGE 7
DS1990A Serial Number iButton 1-Wire Signaling detect a presence pulse, the master must test the logical state of the 1-Wire line at tMSP. The DS1990A 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.
PAGE 8
DS1990A 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 DS1990A Figure 7.
PAGE 9
DS1990A Serial Number iButton Slave-to-Master A read-data time slot begins like a write-one time slot. The voltage on the data line must remain below VILMAX until the read low time tRL is expired. During the tRL window, when responding with a 0, the DS1990A starts pulling the data line low; its internal timing generator determines when this pulldown ends and the voltage starts rising again.
PAGE 10
DS1990A Serial Number iButton Revision History REVISION DATE 033005 DESCRIPTION Redid the formatting based on newer template style. Also deleted the 0F Read ROM command and added a note about presence pulse criteria. 1–8 Created newer template-style data sheet. All Updated Ordering Information with lead-free part numbers.