Series 2000 Reader System High Performance RFM RI-RFM-007B Reference Guide 11-06-21-042 April 1999 1
High Performance RFM RI-RFM-007B April 1999 Second Edition - April 1999 This manual describes the TIRIS High Performance RFM RI-RFM-007B, hereafter referred to as the RFM. Important Notice Texas Instruments reserves the right to change its products or services or to discontinue any product or service at any time without notice. TI provides customer assistance in various technical areas, but does not have full access to data concerning the use and applications of customer's products.
April 1999 Contents Table of Contents Preface.................................................................................................................5 Chapter 1: Product Description ........................................................................7 1.1 General .......................................................................................................8 1.2 Transmitter ...............................................................................................10 1.3 Receiver .
High Performance RFM RI-RFM-007B April 1999 Table Locations Table 1: J1 Pin Functions ................................................................................................................................ 13 Table 2: J2 Pin Functions ................................................................................................................................ 14 Table 3: J4 Pin Functions ............................................................................................................
Preface FCC/PTT Regulations The TIRIS RFM generates RF emissions at 134.2 kHz. The radiation of the fundamental and harmonics will vary with the type of antenna and other devices or functions connected to the RFM. Prior to operating the RFM together with antenna(s), power supply and a control module or other devices, the required FCC, PTT or relevant government agency approvals must be obtained.
High Performance RFM RI-RFM-007B April 1999 Conventions Certain conventions are used in order to display important information in this manual, these conventions are: WARNING: A warning is used where care must be taken, or a certain procedure must be followed, in order to prevent injury or harm to your health. CAUTION: This indicates information on conditions which must be met, or a procedure which must be followed, which if not heeded could cause permanent damage to the RFM.
Chapter 1 Product Description This chapter introduces the RFM component assemblies, showing the transmitter and receiver sections and placement of key user-accessible components. Topic Page 1.1 General .......................................................................................................8 1.2 Transmitter ...............................................................................................10 1.3 Receiver .........................................................................
High Performance RFM RI-RFM-007B April 1999 1.1 General WARNING: Care must be taken when handling the RFM. High voltage across the antenna terminals, all antenna components and some parts of the printed circuit board (PCB) could be harmful to your health. If the antenna insulation is damaged, the antenna should not be connected to the RFM. CAUTION: This product may be subject to damage by electrostatic discharge (ESD). It should be handled by ESD protected personnel at ESD secured workplaces only.
April 1999 Product Description The RFM contains all the analogue functions of a TIRIS reading unit needed to send an energizing signal via the antenna to initialize a TIRIS transponder, to demodulate the received identification signal and 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 Multipage transponders.
High Performance RFM RI-RFM-007B April 1999 1.2 Transmitter 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 are separated from the logic section supply lines and have two pins per line.
April 1999 Product Description CAUTION: The RFM must not be operated in continuous transmit mode when operated at full power output. For details please refer to Section 2, Specifications. When using pulse widths smaller than 50%, the RFM transmitter power stage works in a less efficient way. This leads to an increased power dissipation and thus to higher temperature increase of the transmitter power stage, so ensure that more cooling is provided.
High Performance RFM RI-RFM-007B April 1999 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. JP3 Additional antenna damping connector. JP4 Common-mode noise choke bypass. R409 RXSS noise level adjustment potentiometer. SW1 Default all on. (Pos. 1 CPS setting see Appendix 5.
April 1999 Product Description The bottom view of the RFM is shown in Figure 4. The connectors J1, J2, J3 and J4 are accessible from the underside. J1 is the 16-pin module connector, this carries the supply voltage lines, the data, and the control lines.
High Performance RFM RI-RFM-007B April 1999 CAUTION: The transmitter ground pins GNDP and logic ground pin GND must be connected together externally. The RFM may be otherwise permanently damaged. Table 2 lists the pin functions for the ATI connector J2: The connector type is a 6 pin, 2 row connector with 2.54 mm pin spacing.
April 1999 Product Description Table 4 lists the functions for connector J3. This is a 14 pin, 2 row connector with 2.54 mm pin spacing.
Chapter 2 Specifications This chapter lists the recommended operating conditions, electrical and mechanical characteristics and dimensions. Topic Page 2.1 Recommended Operating Conditions ......................................................18 2.2 Dimensions...............................................................................................
High Performance RFM RI-RFM-007B April 1999 CAUTION: Exceeding recommended maximum ratings may lead to permanent damage of the RFM. The RFM must not be operated in continuous transmit mode when operated at full power output. Install suitable heatsinks when operating the RFM at pulse widths smaller than 50%. 2.1 Recommended Operating Conditions Table 6 shows the recommended operating conditions. Table 6: Operating Conditions Symbol V_VSP I_VSP Parameter min. Supply voltage of transmitter power stage 7.
April 1999 Specifications In order to keep power consumption (P_VSP) below 20 W it is advisable to limit I_VSP. The maximum allowed value, dependent on the configuration, can be determined as follows (in the following examples a supply voltage of 24 V_VSP is used): I_VSP = P_VSP V_VSP x Duty Cycle where Duty Cycle = Example 1: I_VSP = I_VSP = Using Standard/Default Settings (≈10 read cycles/second): 20 W 24V x 0.5 Example 2: Power on time Total Read Cycle Time = 1.
High Performance RFM RI-RFM-007B April 1999 Table 7: Electrical Characteristics Symbol I_VSL Parameter min. Supply current for logic and receiver part in transmit and receive 14 mode ViL Low level input voltage of TXCT0 ViH High level input voltage of TXCT2.4 VoL Low level output voltage of RXDT and RXCK 0 VoH High level output voltage of RXDT and RXCK 4.
April 1999 Specifications Table 8: Timing Characteristics Symbol Parameter min. typ.
High Performance RFM RI-RFM-007B April 1999 2.2 Dimensions All measurements are in millimeters with a tolerance of +/- 0.5 mm unless otherwise noted. 57.6 mm +/- 1.0 mm 4.83 mm +/- 1.0 mm 16.0 mm +/- 1.0 mm 9.9 mm +/- 1.0 mm 8.8 mm +/- 1.0 mm 71.1mm 93 mm +/- 1.0 mm M3 Pressnuts 70.36 mm 83 mm +/- 1.
Chapter 3 Installation This chapter shows how to install the RFM and specifies power supply requirements and connections. Topic Page 3.1 Power Supply Requirements....................................................................24 3.2 Power Supply Connection ........................................................................
High Performance RFM RI-RFM-007B April 1999 3.1 Power Supply Requirements The logic and receiver sections of the RFM must be supplied via the VSL and GND pins with unregulated voltage. The transmitter power stage is separately supplied via VSP and GNDP. As there is no stabilization circuitry on the RFM and as the transmitter power stage needs a regulated supply voltage in order to meet FCC/PTT regulations, the supply voltage for the transmitter power stage must be regulated externally.
April 1999 Installation 3.2 Power Supply Connection Ground pins for the logic/receiver part and the transmitter power stage are not directly connected internally, the two different grounds having to be connected to each other externally. The only internal connection is via resistor R_GND, in order to avoid floating grounds if these grounds are accidentally not connected to each other externally. This is necessary for two reasons: 1.
High Performance RFM RI-RFM-007B • April 1999 Cable lengths longer than 2 m are not recommended. If the application demands cabling longer than 2 m, the logic signal connections between the RFM and the Control Module should be done via a differential interface (for example RS422). Due to different ground potentials at different locations it may also be necessary to provide galvanic separation of the interface signals by, for example, opto-couplers.
Chapter 4 Associated Antenna Systems This chapter discusses antenna requirements and antenna tuning procedures and flowcharts. Topic Page 4.1 Antenna Requirements.............................................................................28 4.2 Antenna Resonance Tuning.....................................................................29 4.3 Tuning Procedure .....................................................................................
High Performance RFM RI-RFM-007B April 1999 4.1 Antenna Requirements In order to achieve high voltages at the antenna resonance circuit and thus high field strength at the antenna for the charge-up (transmit) function, the antenna coil must be high Q. The recommended Q factor for proper operation is listed in Table 11, Antenna requirements. The Q factor of the antenna may vary depending on the type, the construction and the size of the antenna.
April 1999 Associated Antenna Systems When low field strength for larger antennas is necessary (Vpeak <60 V), the antenna resonator can additionally be damped by connecting an onboard damping resistor, which may be done by closing jumper JP3 (see Figure 3). This jumper is open by default. CAUTION: Only a certain maximum antenna resonance voltage is allowed for this option. Please refer to Chapter 2.1, Recommended Operating Conditions, for details.
High Performance RFM RI-RFM-007B April 1999 The following notes refer to antenna resonance tuning in general: Note: If an antenna has to be installed in an environment where metal is present, the tuning of the antenna must be done in this environment, since the presence of metal changes the inductance of the antenna. In addition, the Q factor of the antenna decreases, thereby decreasing the field strength.
April 1999 Associated Antenna Systems Counting-up of the binary weighted tuning capacitors is in principle done in the following way: 1. No jumpers connected. 2. connect C_ATC1 (J3 pins 1 and 2). 3. disconnect C_ATC1 and connect C_ATC2. 4. Connect both C_ATC1 and C_ATC2 (and so on). However, the tuning steps do not offer an absolutely continuously increasing function, due to component tolerances.
High Performance RFM RI-RFM-007B April 1999 START CONNECT ANTENNA TO THE RF MODULE DISCONNECT ALL JUMPERS CONTROL CURRENT INTO VSP PIN INCREASE TUNING CAPACITY BY ONE BINARY STEP CONTROL CURRENT INTO VSP PIN MEASURED VALUE HAS DECREASED IN COMPARISON TO THE PREVIOUS TUNING VALUE No Yes INCREASE TUNING CAPACITY BY ONE BINARY STEP CONTROL CURRENT INTO VSP PIN MEASURED VALUE HAS DECREASED IN COMPARISON TO THE PREVIOUS TUNING VALUE No Yes DECREASE TUNING VALUE BY TWO BINARY STEPS PLUG IN JUMPERS FOR
Appendix 1 Expanding Antenna Tuning Inductance Range It is possible to expand the tuning range of the antenna inductance. This may be necessary when TIRIS standard antennas are used close to metal, when antenna extension cables are used or when customer specific antennas which might not be within the necessary antenna tuning inductance range are used. Note: Please remember that the capacitors of external modules have to be able to withstand higher voltages when used together with a RFM.
High Performance RFM RI-RFM-007B April 1999 The antenna tuning inductance range can be decreased to 13.7 µH in six ranges, as shown in Figure 9 and Table 12. Figure 9: Circuit for Expanding Antenna Tuning Range to Lower Values C1 ANT 2 • C3 • ANT 1 C2 • • • C4 • Table 12: Capacitor Values for Expanding Antenna Tuning Range to Lower Values Antenna inductance range 24.1 µH to 25.9 µH 22.3 µH to 24.0 µH 20.4 µH to 22.2 µH 18.4 µH to 20.3 µH 16.5 µH to 18.3 µH 13.7 µH to 16.
April 1999 Appendix 1 • ANT 2 C4 • ANT 1 • • • C1 C2 C3 • • • Figure 10: Circuit for Expanding Antenna Tuning Range to Higher Values Table 13: Capacitor Values Expanding Antenna Tuning Range to Higher Values (C1, C2 & C3 = 47 nF) Antenna inductance range 28.0 µH to 29.3 µH Capacitor value C4 = 18.3 nF (parallel 6.8 nF, 6.8 nF, 4.7 nF) C4 = 13.6 nF 29.4 µH to 31.0 µH (parallel 6.8 nF, 6.8 nF) C4 = 10 nF 31.1 µH to 32.4 µH C4 = 6.8 nF 32.5 µH to 33.8 µH C4 = 3.98 nF 33.9 µH to 35.0 µH (parallel 3.
Appendix 2 Field Strength Adjustment The magnetic field strength generated determines the charge-up distance of the transponder. The higher the magnetic field strength, the further the transponder charge-up distance. The charge-up distance does not, however, increase linearly with the field strength. The reading distance of a transponder is determined, amongst other factors, by the charge-up distance and the local noise level.
High Performance RFM RI-RFM-007B April 1999 3. Supply voltage of the RFM power stage. The higher the supply voltage of the RFM transmitter power stage (VSP voltage), the higher the field strength which is generated by the RFM assuming that all other parameters remain unchanged. However, the generated field strength does not increase linearly with VSP supply voltage.
Appendix 3 Adjustment of Oscillator Signal Pulse Width The RFM has an built-in feature to allow setting of the pulse width of the transmitter signal coming from the oscillator. This enables the generated field strength to be reduced from 50% down to 0%. For this purpose a pulse width setting resistor may be inserted between J4 pins 3 and 4 on the RFM. Inserting a smaller resistance value decreases the pulse width and thus also the field strength.
High Performance RFM RI-RFM-007B April 1999 Table 14: Oscillator Signal Pulse Width versus Resistor Value (estimated values) Resistor value Ω] [kΩ open 151 59 17 10 shorted Oscillator signal pulse width [%] 50 37 25 12 6 0 Field strength reduction [dB] 0 -3 -6 -12 -18 ∞ CAUTION: When using pulse widths smaller than 50%, the RFM transmitter power stage works less efficiently. This leads to an increased power dissipation and thus to a higher temperature of the transmitter power stage.
Appendix 4 Threshold Level Adjustment The RFM has a built-in receive signal field strength detector with the output signal RXSS- and an on-board potentiometer (R409) to adjust the threshold level of field strength detection. The digital output RXSS- is used for wireless synchronization of two or more reading units. This is necessary to ensure that if more than one reading unit is in an area, they do not interfere with each other.
High Performance RFM RI-RFM-007B April 1999 5. Turn the RXSS- threshold level adjustment potentiometer on the RFM clockwise, until the RXSS- output is just statically inactive. "Statically" means no voltage spikes present on the RXSS- signal. 'Inactive' means that the receive signal strength is below the RXSS- threshold level and not triggering RXSS- (the RXSS- output voltage remains > 4 V). 6.
Appendix 5 Transmitter Carrier Phase Synchronization (CPS) In some applications it is necessary to use several charge-up antennas close to each other. Under these circumstances, the magnetic charge-up fields generated by different antennas superimpose on each other and may cause a beat effect on the magnetic charge-up field, due to the slightly different transmit frequencies of different RFMs. The impact of this effect depends on three factors: 1.
High Performance RFM RI-RFM-007B April 1999 If several antennas are used close to each other, a check should be made to determine if the charge-up field strength changes regularly (i.e. beat effect ). This may be checked by verifying the antenna resonance voltage with an oscilloscope. If the antenna resonator voltage changes periodically by more than approximately 5% of the full amplitude it is appropriate to use wired transmitter carrier phase synchronization.
April 1999 Transmitter Carrier Phase Synchronization Note: When using the transmitter Carrier Phase Synchronization feature, it is absolutely necessary that the read cycles of each of the different Control Modules are synchronized. When the transmitter of the oscillator MASTER RFM is not activated by its Control Module, the oscillator signal output of the oscillator MASTER RFM is disabled.
Appendix 6 Noise Considerations Noise can have a negative effect on the receive performance of the RFM. There are two different kinds of noise: radiated and conducted. Their characteristics are shown in Table 16. Table 16: Characteristics of Radiated and Conducted Noise Radiated Noise Conducted Noise Source Inductive parts for example: Power units, for example: motors, switched deflection coils, motor coils. mode power supplies. Can be seen as voltage spikes or ripple voltage. Path Via magnetic fields.
High Performance RFM RI-RFM-007B April 1999 Note: Both noise types can be either differential or common mode noise. Use common mode noise filters (for example: a BALUN transformer) to reduce common mode noise and use selective filters to reduce differential noise. The following procedure for testing for noise impact should be implemented when the normal set-up for the RFM and antenna gives bad reading distances, even though the antenna is correctly tuned for sufficient transponder charge-up.
Appendix 7 Over Voltage Protection For applications where there is a risk that voltage spikes and noise are on the lines to the RFM, additional protection circuitry and filters must be added. A proposal on how this may be achieved is shown in Figure 13, and this circuit may be used as a guideline for protection circuitry. This may not be sufficient for all applications, however, and must be checked individually when necessary. 1. The supply input has to be protected against voltage spikes.
High Performance RFM RI-RFM-007B April 1999 Figure 13: Circuit for Overvoltage Protection All components must be mounted close to the RFM with the shortest possible wiring C1: 100 nF Ceramic R1: 1 Ohm / 2W V1: Varistor 420V e.g Siemens S10V520K420 R2, R3, R4, R5, R6, R7: C2: 100 µF low ESR 22 Ohm / 0.25W CHOKE: Common D1: ZY18 resp.
