Texas Instruments 2000 series User manual

A TEXAS INSTRUMENTS TECHNOLOGY
Series 2000 Reader SystemHigh Performance Reader Frequency ModuleRI-RFM-007B
Reference Guide
November 2002
SCBU022

A TEXAS INSTRUMENTS TECHNOLOGY
Series 2000 Reader System
High Performance Reader Frequency ModuleRI-RFM-007B
Reference Guide
Literature Number: SCBU022November 2002

Contents
Preface ............................................................................................................................... 5
1 Product Description ................................................................................................... 71.1 General ............................................................................................................... 81.2 Transmitter ........................................................................................................... 91.3 Receiver ............................................................................................................ 101.4 RFM Connectors and Jumpers .................................................................................. 10
2 Specifications .......................................................................................................... 152.1 Recommended Operating Conditions .......................................................................... 162.2 Dimensions ......................................................................................................... 19
3 Installation ............................................................................................................... 213.1 Power Supply Requirements .................................................................................... 223.2 Power Supply Connection ........................................................................................ 22
4 Associated Antenna Systems .................................................................................... 254.1 Antenna Requirements ........................................................................................... 264.2 Antenna Resonance Tuning ..................................................................................... 274.3 Tuning Procedure ................................................................................................. 27
5 Regulatory, Safety & Warranty Notices ....................................................................... 315.1 Regulatory Notes .................................................................................................. 325.1.1 FCC Notices (U.S.A) ..................................................................................... 325.1.2 CE Conformity (Europe) ................................................................................. 32
A Expanding Antenna Tuning Inductance Range ............................................................. 33
B Field Strength Adjustment ......................................................................................... 37
C Adjustment of Oscillator Signal Pulse Width ................................................................ 39
D Threshold Level Adjustment ...................................................................................... 41
E Transmitter Carrier Phase Synchronization (CPS) ........................................................ 43
F Noise Considerations ................................................................................................ 45
G Over Voltage Protection ............................................................................................ 47
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List of Figures
1-1 RFM Block Schematic ....................................................................................................... 81-2 Pulse Width Examples ...................................................................................................... 91-3 RFM Top View .............................................................................................................. 111-4 RFM Bottom View .......................................................................................................... 122-1 Mechanical Dimensions ................................................................................................... 193-1 External Ground Connection (GND to GNDP) ......................................................................... 234-1 Tuning Example Showing Increase of Total Tuning Capacity and Generated Field Strength (TypicalValues) ....................................................................................................................... 284-2 Flow Chart for Tuning the Antenna to Resonance ..................................................................... 29A-1 Circuit for Expanding Antenna Tuning Range to Lower Values ...................................................... 33A-2 Circuit for Expanding Antenna Tuning Range to Higher Values ..................................................... 34E-1 Distance Between Antennas (Top View) ................................................................................ 43F-1 Noise Testing Configuration .............................................................................................. 46G-1 Circuit for Overvoltage Protection ........................................................................................ 48
List of Tables
1-1 J1 Pin Functions ............................................................................................................ 121-2 J2 Pin Functions ............................................................................................................ 131-3 J4 Pin Functions ............................................................................................................ 131-4 J3 Pin Functions ............................................................................................................ 131-5 Antenna Connectors ....................................................................................................... 141-6 Transmitter Carrier Phase Synchronization (CPS) Dip Switch SW1 ................................................ 142-1 Operating Conditions ...................................................................................................... 162-2 Electrical Characteristics .................................................................................................. 172-3 Timing Characteristics ..................................................................................................... 182-4 Mechanical Parameters ................................................................................................... 183-1 Power Supply Ripple Specifications ..................................................................................... 224-1 Antenna Requirements .................................................................................................... 26A-1 Capacitor Values for Expanding Antenna Tuning Range to Lower Values ......................................... 34A-2 Capacitor Values Expanding Antenna Tuning Range to Higher Values ............................................ 35C-1 Oscillator Signal Pulse Width vs Resistor Value (Estimated Values) ............................................... 39E-1 Maximum Distances Between Antennas ................................................................................ 43F-1 Characteristics of Radiated and Conducted Noise .................................................................... 45
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PrefaceSCBU022 – November 2002
Fifth Edition – November 2002This manual describes the TI-RFid™ High Performance Reader Frequency Module RI-RFM-007B,hereafter referred to as the RFM.
Conventions
Certain conventions are used in order to display important information in this manual, these conventionsare:
WARNINGA WARNING IS USED WHERE CARE MUST BE TAKEN, OR ACERTAIN PROCEDURE MUST BE FOLLOWED, IN ORDER TOPREVENT INJURY OR HARM TO YOUR HEALTH.
CAUTION
This indicates information on conditions which must be met, or a procedurewhich must be followed, which if not heeded could cause permanent damage tothe RFM.
Note: Indicates conditions which must be met, or procedures which must be followed, to ensureproper functioning of the RFM.
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Trademarks
Trademarks
The TI-RFid logo and the words TI-RFid and Tag-it are trademarks or registered trademarks of TexasInstruments.
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Chapter 1SCBU022 – November 2002
Product Description
This chapter introduces the RFM component assemblies, showing the transmitter andreceiver sections and placement of key user-accessible components.
Topic .................................................................................................. Page
1.1 General ...................................................................................... 81.2 Transmitter ................................................................................ 91.3 Receiver ................................................................................... 101.4 RFM Connectors and Jumpers ................................................... 10
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1.1 General
PWM
TX
Oscillator
RX
demodulator
RXSS-
Interface
Antenna
Circuit
TX/RX
Antenna
RX
Amplifier
RXSS
threshold
ATI
Int
TX Power
Stage
CPS
TXCT-
RXDT
RXCK
ATI
6
Threshold
Demodulator
PWM Control Input
Overvoltage Protection
General
WARNINGCARE MUST BE TAKEN WHEN HANDLING THE RFM. HIGHVOLTAGE ACROSS THE ANTENNA TERMINALS, ALL ANTENNACOMPONENTS AND SOME PARTS OF THE PRINTED CIRCUITBOARD (PCB) COULD BE HARMFUL TO YOUR HEALTH. IF THEANTENNA INSULATION IS DAMAGED, THE ANTENNA SHOULDNOT BE CONNECTED TO THE RFM.
CAUTION
This product may be subject to damage by electrostatic discharge (ESD). Itshould be handled by ESD protected personnel at ESD secured workplacesonly. The transmitter power output stage can only operate with a limited dutycycle. Please pay attention to this whilst performing antenna tuning procedures.Ground pins GND and GNDP must be connected externally to avoid damage tothe unit.
The RFM is an integral part of the TI-RFid system. Coupled with a Control Module and an antenna, it isused for wireless identification of TI-RFid transponders. A block schematic is shown in Figure 1-1 .
Figure 1-1. RFM Block Schematic
The RFM contains all the analogue functions of a TI-RFid reading unit needed to send an energizingsignal via the antenna to initialize a TI-RFid transponder, to demodulate the received identification signaland to send the received data together with clock signals to a Control Module.
The RFM also sends the necessary programming and addressing signals to Read/Write and Multipagetransponders.
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1.2 Transmitter
Pulse width of 50% Pulse width of 12.5%
Transmitter
The data input and output lines, which are connected to a data processing unit, are low-power SchottkyTTL and HCMOS logic compatible.
The functions of the RFM are described in Section 1.2 .
The transmitter power stage is supplied with power via two separate supply lines VSP and GNDP.Because of the high current requirements for the transmitter power stage, these supply lines areseparated from the logic section supply lines and have two pins per line.
The ground pins for the logic section and the transmitter are not connected internally in order to avoidpossible problems with a high resistivity of GNDP pins and in order to increase flexibility when using longsupply lines. Pins GND and GNDP must be connected to each other externally. For more details, refer toSection 3.1 , Power Supply Connection.
The regulated transmitter power stage supply may vary between +7 V and +24 V. The supply lines VSPand VSL should be connected together when the supply voltage is +7 V or more. For details refer toChapter 2 , Specifications.
Note: The RFM has an in-built temperature protection circuit which sharply limits the transmitterpower stage output if an over-current situation or an over-temperature environmentcauses the temperature to exceed the allowed limits. After the device is switched off andhas time to recover (when the temperature drops again or the over-current situation isotherwise rectified) the unit reverts to normal operation when it is switched on again. Suchan occurrence is an indication that the RFM is not being operated within specification.
The transmit frequency (134.2 kHz) from the oscillator is fed to the pulse width modulator (PWM). Bychanging the value of a resistor, the PWM can set the pulse width ratio between 0% and 50%. For anexample of two different oscillator signal pulse widths see Figure 1-2 . Decreasing the 134.2 kHz frequencypulse width ratio decreases the generated transmit (charge-up) field strength.
It is therefore possible to adjust the generated field strength by selecting different pulse width ratios. Formore information about setting the field strength, refer to Appendix B , Field Strength Adjustment.
Figure 1-2. Pulse Width Examples
CAUTION
The RFM must not be operated in continuous transmit mode when operated atfull power output. For details please refer to Chapter 2 , Specifications. Whenusing pulse widths smaller than 50%, the RFM transmitter power stage works ina less efficient way. This leads to an increased power dissipation and thus tohigher temperature increase of the transmitter power stage, so ensure thatmore cooling is provided.
Note: If the RFM is going to be physically located within the antenna field, it may be necessaryto shield the module.
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1.3 Receiver
1.4 RFM Connectors and Jumpers
Receiver
The signal received from the transponder is a frequency shift keying (FSK) signal with typical low and highbit frequencies of 134.2 kHz and 123.2 kHz respectively. The signal is received from the antennaresonator, which is capacitively coupled to the receiver.
The signal RXCK is the reference clock signal to decode the RXDT data stream. The RXCK signalchanges from low to high level during each data bit and the RXDT signal is valid before and after thispositive slope for a certain time window. For more details refer to Table 2-3 , Timing Characteristics.
The receiver also has a built-in RF receive signal strength detector. The receive signal strength isindicated by the digital output RXSS-.
RXSS- becomes active ( logic low level) when the received RF signal strength exceeds a defined level.This threshold level can be adjusted with a potentiometer (R409) on the RFM. The potentiometer islocated near SW1 on the board. See Figure 1-3 , RFM Top View.
The RXSS- output is used for detection of other transmitting reading units and thus can be used forwireless read cycle synchronization of several reading units.
There are a number of connectors, jumpers and other components on the RFM available for use.
These are:
J1 Connector for supply voltages and interface signal lines to and from the RFMJ2 Connector for the (optional) Antenna Tuning Indicator (ATI), which can be used for easyantenna tuning during installation.J3 Connector for antenna resonance tuning, used to connect the required tuning capacitors.J4 Connector for field strength adjustment resistor and also direct access to receiver input.J5 Additional antenna damping Jumper.J6 Common-mode noise choke bypass.R409 RXSS noise level adjustment potentiometer.SW1 Default all on. (SW1/1 CPS setting see Appendix E .)ANT1/ANT2 (Two M3 screw connectors) Connect the transmit/receive (TX/RX) antenna to the RFM.
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