Detailed Product Description

ibutton,

Smart Card (TM card, Information Button, Touch Memory)

Type: TM1990A-F5

Dimension: diameter 16.25MM, high 5.9MM

Function: anti-water, anti-shake, anti-rust; the shell is made by 304 stainless steel, never rust; the chip is made by new TM1990A wafer, unique 64bit serial number of the world. Full compatible with ds1990A(R) .

TM1990A SPECIAL FEATURES

l       TM1990A is full compatible with DS1990A, DS1990R and i1990A

l       Unique 48bit serial number

l       Low-cost electronic key for access control

l       8-bit CRC for checking data integrity

l       Can be read in less than 5 ms

l       Operating temperature range of -40°C to  +85°C

COMMON INFORMATION BUTTON FEATURES

l       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.

l       Multidrop controller for MicroLAN.

l       Digital identification by momentary contact.

l       Chip-based data carrier compactly stores information.

l       Data can be accessed while affixed to an object.

l       Economically communicates to bus master with a single digital signal at 16.3k bits per second.

l       Standard 16 mm diameter and 1-Wire protocol ensure compatibility with INFORMATION BUTTON family.

l       Button shape is self-aligning with cupshaped probes.

l       Durable stainless steel case engraved with registration number withstands harsh environments.

l       Easily affixed with self-stick adhesive backing, latched by its flange, or locked with a ring pressed onto its rim.

l       Presence detector acknowledges when reader first applies voltage.

ORDER INFOMATION

INFORMATION Button DESCRIPTION

The TM1990A Serial Number INFORMATION BUTTON is a rugged data carrier that acts as an electronic registration

number for automatic identification. The TM1990A consists of a factory-lasered, 64-bit ROM that

includes an unique 48-bit serial number, an 8-bit CRC and an 8-bit Family Code (01h). Data is transferred

serially via the 1-Wire protocol which requires only a single data lead and a ground return. The TM1990A

is fully compatible with the TM1990A Serial Number INFORMATION BUTTON but provides the additional 1-Wire protocol

capability that allows the Search ROM command to be interpreted by the TM1990A and therefore allows

multiple TM1990A devices to reside on a single data line.

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, allowing the TM1990A to

be used easily by human operators. Accessories permit the TM1990A to be mounted on plastic key tabs,

photo ID badges, printed circuit boards or any smooth surface of an object. Applications include access

control, work-in-progress tracking, tool management and inventory control.

OPERATION

The TM1990As internal ROM is accessed via a single data line. The 48-bit serial number, 8-bit family

code and 8-bit CRC are retrieved using the Dallas 1-Wire protocol. This protocol defines bus transactions

in terms of the bus state during specified time slots that are initiated on the falling edge of sync pulses

from the bus master. All data is read and written least significant bit first.

1-WIRE BUS SYSTEM

The 1-Wire bus is a system which has a single bus master system and one or more slaves. In all instances,

the TM1990A is a slave device. The bus master is typically a microcontroller. The discussion of this bus

system is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire

signaling.

Hardware Configuration

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 an

open drain connection or 3-state outputs. The TM1990A is an open drain part with an internal circuit

equivalent to that shown in Figure 2. The bus master can be the same equivalent circuit. If a bidirectional

pin is not available, separate output and input pins can be tied together. The bus master requires a pullup

resistor at the master end of the bus, with the bus master circuit equivalent to the one shown in Figure 3.

The value of the pullup resistor should be approximately 5 kW for short line lengths. A multidrop bus

consists of a 1-Wire bus with multiple slaves attached. The 1-Wire bus has a maximum data rate of 16.3k

bits per second.

The idle state for the 1-Wire bus is high. If, for any reason, a transaction needs to be suspended, the bus

MUST be left in the idle state if the transaction is to resume. If this does not occur and the bus is left low

for more than 120 ms, one or more of the devices on the bus may be reset.