MLX90109 125kHz RFID Transceiver Features and Benefits Integrated transceiver for 100kHz to 150kHz range ASK transponder (tags) Unique Parallel Antenna concept for maximum power efficiency. No external quartz reference required. No zero modulation problems. SO8 package and high level of integration for compact reader design. On chip decoding (Biphase and Manchester ASK) for fast system design and ease of use. Baud rate selectable “on-chip” filtering for maximum sensitivity. Open drain data and clock outputs for 2-wire serial communication. Power down mode available. ON/OFF keying modulation for the downlink communication to the tag. Applications Examples Car Immobilizers Portable readers Access control House held appliances ….. Ordering Information Part No. MLX90109 MLX90109 Temperature Code C (0°C to 70°C) E (-40°C to 85°C) 1 Functional diagram VDD ! "# $ ! ! ( ) ( " * 3901090109 Rev 007 + % & ' ' & ' Package Code DC (SOIC 8) DC (SOIC 8) Option code --- 2 Description The MLX90109 is a single chip RFID transceiver for the 125kHz range. It realizes a state of the art Read-Write performance for minimum system cost and minimum power consumption. An external coil (L), operating at the same time as an antenna, and capacitor (C) are connected as a parallel resonant circuit, that determines the carrier frequency and the oscillator frequency of the reader. This eliminates zero modulation effects by perfect antenna tuning, and avoids the need for an external oscillator. The reader IC can easily be switched to power down by setting the antenna amplitude to zero. The MLX90109 can be configured to decode the transponder signal on-chip. In this case the decoded signal is available through a 2-wire interface with clock and data. For minimum interface wiring, the non-decoded transponder signal can also be made available on a single wire interface. Page 1 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver Table of Contents Functional diagram .......................................................................................................................................................................... 1 Description...................................................................................................................................................................................... 1 1 Maximum ratings .......................................................................................................................................................................... 3 2 Pad definitions and descriptions..................................................................................................................................................... 3 3 MLX90109 Electrical Specifications................................................................................................................................................ 4 4 Block Diagram .............................................................................................................................................................................. 5 5 Functional block description .......................................................................................................................................................... 5 5.1 Oscillator............................................................................................................................................................................... 5 5.2 Amplitude detector ................................................................................................................................................................. 5 5.3 Filter settings......................................................................................................................................................................... 5 5.4 Digital demodulator ................................................................................................................................................................ 5 6 Detailed General Description ......................................................................................................................................................... 6 6.1 Antenna voltage definition ...................................................................................................................................................... 6 6.2 Power Down/Power On .......................................................................................................................................................... 6 6.3 Write operation ...................................................................................................................................................................... 6 7 System design parameters ............................................................................................................................................................ 7 7.1 Auto start-up condition ........................................................................................................................................................... 7 7.2 Antenna current ..................................................................................................................................................................... 7 7.3 Antenna voltage..................................................................................................................................................................... 8 7.4 Antenna Impedance............................................................................................................................................................... 8 8 Typical operating configuration: READ ........................................................................................................................................... 9 8.1 Absolute minimum schem atic ................................................................................................................................................. 9 8.2 Power consumption ............................................................................................................................................................... 9 8.3 Noise cancellation.................................................................................................................................................................10 8.4 Integrated decoding ..............................................................................................................................................................10 8.5 Close coupling......................................................................................................................................................................10 9 Typical operating configuration: WRITE.........................................................................................................................................11 9.1 ON/OFF keying (FDX-B100)..................................................................................................................................................11 10 Reliability Information.................................................................................................................................................................12 11 ESD Precautions .......................................................................................................................................................................12 12 FAQ ..........................................................................................................................................................................................13 12.1 Is it possible to make proportional modulation (modulation depth less than 100%) with the MLX90109? ...................................13 12.2 How should I read data information from a transponder up to 15cm?......................................................................................13 12.3 Is it possible to increase the output power of the MLX90109 transceiver? ...............................................................................13 12.4 Are there any specific coils available for the MLX90109 transceiver? .....................................................................................13 13 Package Information ..................................................................................................................................................................14 13.1 Plastic SO8 ........................................................................................................................................................................14 14 Disclaimer .................................................................................................................................................................................15 3901090109 Rev 007 Page 2 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 3 Maximum ratings Supply voltage (Vdd with respect to Vss) Input voltage on any pin (except COIL, DATA and CLOCK) Input voltage on COIL, DATA and CLOCK Maximum junction temperature Table 1: Absolute maximum ratings Symbol Condition Min VDD DC -0.3 VIN -0.3 Vclamp -0.3 TJ Max 6 VDD+0.3 15 150 Unit Volts Volts Volts ºC Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute-maximumrated conditions for extended periods may affect device reliability. 4 Pad definitions and descriptions Pad Name Function COIL Oscillator output VSS Ground SPEED 2kbaud/4kbaud selection MODU Input for amplitude setting MODE Biphase/Manchester selection CLOCK Clock output of decoder DATA Data output of decoder VDD Power Supply Table 2: Pin description MLX90109 Plastic SO8 3901090109 Rev 007 Page 3 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 5 MLX90109 Electrical Specifications o o DC Operating Parameters TA = -40 C to 85 C, Fres = 125kHz Antenna parameters: Lant = 73.6uH, Qant =17.3Ω, Zant=1kΩ Parameter. Symbol Supply Voltage VDD Resonance Frequency Fres (Depends on the antenna) Temperature drift ∆Fres (T) Vsens Fres = 125 kHz (Depends on the application) Sensitivity (note 1) Amplitude Offset (note 2) Power down voltage (on MODU pin) Power up voltage (on MODU pin) Power down Current Supply Current (excluding antenna supply current) (note 3) Antenna supply current (note 4) Leakage current on pins COIL, MODE, SPEED, MODE, DATA Output voltage DATA and CLOCK pin Table 3: Electrical specifications Test Conditions Min Typ 3.1 Vos 100 125 -1 0 4.0 2.2 3.2 1.3 0 V kHz % 30 mVpp 0.15 0.35 4.9 3.0 4.3 2.4 1.5 V 4 mA IDD VDD=5V, VMODU = 0.8V 1.8 IDDant (Depends on the application) 2.8 Ileak (Power down) Vol Isink = 2.5mA -1.5 5.5 150 +1 IDDpd Vpu Units 10 VDD=5V VDD=3.1V VDD=5V VDD=3.1V VMODU = VDD Vpd Max V V A mA 1.5 A 0.4 V Note 1: The sensitivity is defined as the minimum amplitude of the 2kHz - modulation generated by the transponder, demodulated and decoded by the reader. This parameter depends on the application: _ the value of VDD _ the antenna _ the code sent to the reader Note 2: The antenna amplitude (peak) is: Vant = VDD – VMODU + Vos Note 3: The supply current depends slightly dependant on the antenna drive current IDDant: IDD ≈ 1.3 mA + IDDant / 6.3 Note 4: The antenna supply current (called IDDant) is the DC supply current driven by the chip through the antenna. 3901090109 Rev 007 Page 4 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 6 Block Diagram VDD ( / . ! ) + . + , + & ( ) ( ' * , # $ ! ! ! 7 Functional block description 7.1 Oscillator The oscillator frequency is locked on the antenna resonance frequency. The clock of the filter is derived from the oscillator. In this way, its characteristics are locked to the transmission frequency. As the antenna is used to determine the carrier frequency, the antenna is always perfectly tuned to resonance. Consequently the MLX90109 is not sensitive to zero modulation. (The so-called “zero modulation” is the phenomena whereby the tag does modulate properly, but no amplitude modulation can be observed at the reader coil). 7.2 Amplitude detector The amplitude demodulator of the transceiver detects the AM signal generated by the tag. This signal is filtered and amplified by an on-chip switched capacitor filter before feeding the digital decoder. The same signal is fed back to close the control loop of the antenna voltage. 7.3 Filter settings By setting the SPEED pin to VDD or to GND, the filtering characteristics are optimized for either 2 or 4 kbaud. VSS SPEED 4kBaud MODE Biphase (*) Internally strapped to VDD/2 FLOAT (*) No decoding VDD 2kBaud Manchester 7.4 Digital demodulator The MODE pin allows to define whether the MLX90109 will issue directly the filtered data stream on the DATA pin (MODE floating), or decode it in Manchester (MODE = VSS) or Biphase (MODE = VDD). In these two decoding modes, the MLX90109 issues the tag data on the DATA pin at the rising edge of the clock, 3901090109 Rev 007 Page 5 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver which is issued on the CLOCK pin. Both CLOCK and DATA are open drain outputs and require external pullups. 8 Detailed General Description The MLX90109 is a reader IC working in a frequency range of 100 to 150kHz, and designed for use with a parallel L-C antenna. This concept requires significantly less current than traditional serial antennas, for building up the same magnetic field strength. It is limited to proximity read base-stations, since the voltage amplitude (Vant) is limited by the applied supply voltage. V ANT < VDD 8.1 Antenna voltage definition In order to use the driver FET as an ideal current source, the voltage on the coil pin should remain higher than the saturation voltage of the driver FET (typically 0.5V) for up to 14mA driver current (Idriver). The voltage on the MODU pin (VMODU) controls the amplitude of the antenna voltage Vant, as follows: V ANT = VDD − VMODU + VOS with VOS, the offset relative to the VMODU level. Because this offset can be as much as 300mV, VMODU should be higher than 0.8V for correct operation. 8.2 Power Down/Power On By setting VMODU higher than Vpd (preferably to VDD) the MLX90109 goes in power down. The antenna voltage will fade to 0V. The MLX90109 powers up by pulling VMODU below Vpu. 8.3 Write operation A sequence of power up / power down periods sets the antenna voltage ON and OFF. This feature allows to simply make an ON/OFF keying downlink to the transponder. Typically, VMODU is toggled between 5V and 0.8V. Antenna fade-out is related to the quality factor of the antenna (Qant) and its starting-up takes about 3 carrier periods. Refer to the section “Typical operating configurations” further in this document for more detailed information and practical hints. 3901090109 Rev 007 Page 6 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 9 System design parameters The antenna driver FET is switched on as soon as the antenna voltage V(COIL) drops below VDD (see graphical representation below). The MLX90109 will inject a current Idriver into the antenna to make its amplitude follow the voltage on the MODU pin. In order to have the antenna start swinging on the resonance frequency, the chip needs to provide a positive feedback loop. This loop requires a minimal voltage swing at the COIL pin in order to be operational (typically 100mVpp). Below this value, the MLX90109 may not be able to retrieve its clock. Graph: Antenna voltage and Driver current during normal operation. VMODU=0.8V for VDD=5V. The dashed curve shows the antenna voltage when the reader has been powered down. The Driver current is a square wave with a 45% duty cycle. 9.1 Auto start-up condition Pulling VMODU, at power on, from 5V to less than Vpu will set the driver FET on. Provided the voltage drop on the coil pin is large enough (as explained above), the feedback loop is closed and the oscillation will increase in amplitude. To obtain the required positive feedback to start-up the oscillation successfully, Zant should be larger than 1kΩ. This is so called “auto start-up condition”. 9.2 Antenna current The MLX90109 is specified to drive maximum 14mA antenna drive current (Idriver). The AC equivalent supply current (IDDant) can be calculated: (1) I DDant = 2 π ⋅ sin(π ⋅ α ) ⋅ I driver = 0.63 ⋅ I driver with α the duty cycle which is typically 45%. The current that the MLX90109 can inject at each oscillation onto the total antenna current is therefore limited to 9mA in correctly designed reader base stations. The actual antenna current that generates the magnetic field can be calculated as: (2) I ant = Qant ⋅ I DDant 3901090109 Rev 007 Page 7 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver A typical coil quality factor (Qant) value is 23 (see MLX90125), resulting in antenna currents of about 100mA This current resonance of the parallel antenna allows to build very low power reader base stations, contrary to serial antenna based versions. Readers using a serial antenna can leverage their voltage resonance to drive bigger antenna’s for long distance reading up to 1m, whereas the MLX90109 is designed to drive antennas to obtain a reading distance of 1cm up to 15cm (6”) (depending on efficiency and dimensions). 9.3 Antenna voltage The antenna voltage amplitude can easily be calculated as: (3) Vant = V DD − VMODU + VOS 9.4 Antenna Impedance Clearly, the antenna impedance is an important system design parameter for the MLX90109. (4) Vant I DDant Z ant = The antenna impedance can also be calculate as: (5) with Z ant = Qant ⋅ ω res ⋅ Lant res = 2π*Fres From (4) and (5): Vant I DDant Qant ⋅ ω res ⋅ Lant = => Qant ⋅ I DDant = Vant ω res ⋅ Lant Finally in comparison with the formula (2): (6) I ant = Vant ω res ⋅ Lant From the formula above, it is clear that Qant has no influence on Iant. Increasing Qant is equivalent to reduce the antenna supply current IDDant, hence it reduces the overall current consumption. Using the previous formula (6), it is possible to define the proportionality between the total number of ampereturns, generating the magnetic field and the inductance of the antenna (With Nant the number of turns of the antenna coil) : Vant with ωres ⋅ Lant 1 N ant ⋅ I ant 0 Lant N ant ⋅ I ant = N ant ⋅ (7) Lant 0 N ant 2 Hence, to generate a strong field, it is better to choose a low antenna inductance. Limitation to this is given by the minimal antenna impedance (Zant > 1kΩ) and the Q that one can achieve for such an antenna: (8) Lmin = 3901090109 Rev 007 Z min Qant ⋅ ω res Page 8 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver Remarks (3) Note: Mind that in reality the strong coupling with the tag may drastically reduce the antenna impedance. (4) Note: Mind that the quality factor of the antenna (Qant) result in the quality factor of the coil and the quality factor of the capacitance as: (9) Qant = Qcoil // Qcapaci tan ce So, capacitance with a low quality factor may also reduce the antenna impedance. 10 Typical operating configuration: READ 10.1 Absolute minimum schematic The MLX90109 is a highly integrated reader IC. As can be seen in the application schematic below, only two resistors (to set VMODU) are required, next to the antenna inductance and tune capacitor. The interface with the microcontroller can be realized with 1 connection, and the supply line. In this case, the MODE pin is left floating, and the integrated decoding is not used. Capacitances C1 and CD can be added for a better noise cancellation. VDD Lant Ctune C1 R1 SPEED MODU 1 2 3 4 8 7 6 5 VDD DataIn Rpull_Clock VSS MLX90108 COIL Rpull_Data CD ClockIn MODE R2 Microcontroller 10.2 Power consumption If power consumption is not critical and the reader does not have to be put in power down, the MODU voltage can be strapped to the required level (between 0.8V and Vpd). However, the power consumption can be reduced by controlling the voltage on VMODU pin (e.g. with an IO port of a microcontroller). 3901090109 Rev 007 Page 9 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 10.3 Noise cancellation The read performance of a reader is linked with its robustness versus noise. The IC design has been optimized to get a high signal-to-noise ratio (SNR). The resonant antenna is a natural band-pass filter, which becomes more effective as Qr increases. The MLX90109 has an internal first-order filtering of the envelope that changes accordingly to the setting of the SPEED pin, to fit to the Biphase and Manchester data spectrum: 2kbaud (speed pin to VDD) 4kbaud (speed pin to VSS) : : 400Hz to 3.6kHz 800Hz to 7.2kHz Noise rejection could also be improved by a careful PCB design, and by adding decoupling capacitance(s) on the supply lines. Most sensitive pins for noise injection (EMI) are MODU and VDD. Since they directly determine Vant, the noise may be considered as an amplitude modulation (AM) data from a transponder. If the noise on both pins were identical it would cancel out, giving a very noise-insensitive reader. Adding a capacitor C1 between MODU and VDD, together with R1 and R2 yields a high pass filter with cut-off frequency at: 1 2 ⋅ π ⋅ ( R1 // R2 ) ⋅ C1 Typically the filter should short all noise in the data spectrum, but for many cases, it might be beneficial to set it to less than the net frequencies (50Hz, 60Hz). For example, R1=100kΩ and R2=19kΩ for setting MODU, with C1=220nF gives a cut off frequency = 45Hz. The DATA and CLOCK open-drain drivers have been dimensioned to drive strong loads. So take care to use high ohmic (100kΩ) pull up resistances when the loads are low. 10.4 Integrated decoding The MLX90109 provides the option to have a decoded output. This significantly reduces the complexity of the microcontroller software. The data is available when the clock output is high. The clock output has a 50% duty cycle if the data is valid. When the noise level is stronger than the signal level, for instance when no tag is present in the reader field, the duty cycle will be random. The microcontroller can use this feature to detect the presence of a tag: in that case, it must allow some asymmetry on the clock. As the sampling error may be 4 s, it should allow 8 or 12 s of margin. Remark that when the MLX90109 picks up a Manchester-encoded signal whereas the MODE pin is strapped to VSS (= Biphase decoding), the clock will also be asymmetric. 10.5 Close coupling For very short operating distances, a strong coupling with a tag may drastically reduce the antenna impedance Zant. If the current (Idriver) driven by the antenna driver FET goes higher than 14mA, the antenna voltage Vant can be reduced and the MLX90109 will not be able to read the transponder. Coupling effect is application-dependent and must be evaluated case by case. 3901090109 Rev 007 Page 10 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 11 Typical operating configuration: WRITE 11.1 ON/OFF keying (FDX-B100) The basic principle is to switch the voltage on MODU between 0V and VDD. The antenna will reach its maximum amplitude in less than 3 periods when MODU is stepped down from VDD to VSS. Setting the chip in power-down (step VMODU up to VDD) will let the antenna fade-out with a time constant depending on Qant. For fast protocol, an additional drain resistor on MODU controlled by the microcontroller can increase the fall time if required (refer to the application note MLX90109 “100% modulation (ON/OFF Keying)”. VDD Lant Ctune 1 VSS 2 SPEED MODU 3 4 8 MLX90108 R1 7 6 5 VDD DataIn Rpull_Clock COIL C1 Rpull_Data CD ClockIn MODE R2 Microcontroller 3901090109 Rev 007 Page 11 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 12 Reliability Information This Melexis device is classified and qualified regarding soldering technology, solderability and moisture sensitivity level, as defined in this specification, according to following test methods: • • • • • • IPC/JEDEC J-STD-020 Moisture/Reflow Sensitivity Classification For Nonhermetic Solid State Surface Mount Devices (classification reflow profiles according to table 5-2) EIA/JEDEC JESD22-A113 Preconditioning of Nonhermetic Surface Mount Devices Prior to Reliability Testing (reflow profiles according to table 2) CECC00802 Standard Method For The Specification of Surface Mounting Components (SMDs) of Assessed Quality EIA/JEDEC JESD22-B106 Resistance to soldering temperature for through-hole mounted devices EN60749-15 Resistance to soldering temperature for through-hole mounted devices MIL 883 Method 2003 / EIA/JEDEC JESD22-B102 Solderability For all soldering technologies deviating from above mentioned standard conditions (regarding peak temperature, temperature gradient, temperature profile etc) additional classification and qualification tests have to be agreed upon with Melexis. The application of Wave Soldering for SMDs is allowed only after consulting Melexis regarding assurance of adhesive strength between device and board. Based on Melexis commitment to environmental responsibility, European legislation (Directive on the Restriction of the Use of Certain Hazardous substances, RoHS) and customer requests, Melexis has installed a Roadmap to qualify their package families for lead free processes also. Various lead free generic qualifications are running, current results on request. For more information on manufacturability/solderability see following page at our website: http://www.melexis.com/html/pdf/MLXleadfree-statement.pdf 13 ESD Precautions Electronic semiconductor products are sensitive to Electro Static Discharge (ESD). Always observe Electro Static Discharge control procedures whenever handling semiconductor products. 3901090109 Rev 007 Page 12 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 14 FAQ 14.1 Is it possible to make proportional modulation (modulation depth less than 100%) with the MLX90109? The amplitude of the MLX90109 antenna can be adjusted on the fly by changing the MODU pin level between Vpu and Vpd. However, the MLX90109 cannot change instantaneously the voltage on its antenna according to a voltage step on MODU pin, and a transient waveform will appear on the voltage antenna. This particular waveform may disturb the transponder and in the worst case (modulation depth more than 20%) the MLX90109 may stop its oscillation. Using the MLX90109 with proportional modulation (modulation depth less than 100%) is not recommended and supported by Melexis and must be evaluated case by case. 14.2 How should I read data information from a transponder up to 15cm? The reading distance depends on the complete system composed by the reader and the transponder. A reading distance with the MLX90109 transceiver up to 15cm has been demonstrated with a specific reader’s antenna (diameter = 130mm, Inductance = 44 H, Quality factor Qant = 87,2 @125kHz) and a transponder with a credit card size antenna (80 x 50mm). 14.3 Is it possible to increase the output power of the MLX90109 transceiver? The output power is limited by the supply voltage of the MLX90109 transceiver (Vant cannot be higher than VDD-VMODU+Vos). The only solution to increase the output power is to use an external buffer transistor supplied with a higher voltage. This configuration requires two separate connections to transmit the power to the antenna and to receive the modulation signal from a transponder. The output power of the MLX90109 cannot be increased with an external buffer transistor, because it uses the same connection (COIL pin) to transmit the energy to the antenna and to receive the modulation signal from a transponder. 14.4 Are there any specific coils available for the MLX90109 transceiver? The MLX90125CZA-A is a 18mm coil developed by Melexis to be used with the evaluation board EVB90109. It is available and the datasheet can be found on the Melexis website. 3901090109 Rev 007 Page 13 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 15 Package Information 15.1 Plastic SO8 E1 E 1 2 3 D α A1 A e L b all Dimension in mm, coplanarity < 0.1mm D E1 E A A1 e b L a min 4.80 3.81 5.80 1.32 0.10 1.27 0.36 0.41 0° max 4.98 3.99 6.20 1.72 0.25 0.46 1.27 8° all Dimension in inch, copl anarity < 0.004” 3901090109 Rev 007 min 0.189 0.150 0.2284 0.060 0.0040 0.05 0.014 0.016 0° max 0.196 0.157 0.2440 0.068 0.0098 0.018 0.050 8° Page 14 of 15 Data Sheet Sep/04 MLX90109 125kHz RFID Transceiver 16 Disclaimer Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. Melexis reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with Melexis for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical lifesupport or life-sustaining equipment are specifically not recommended without additional processing by Melexis for each application. The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of Melexis’ rendering of technical or other services. © 2004 Melexis NV. All rights reserved. For the latest version of this document, go to our website at www.melexis.com Or for additional information contact Melexis Direct: Europe and Japan: Phone: +32 1367 0495 E-mail: [email protected] 3901090109 Rev 007 All other locations: Phone: +1 603 223 2362 E-mail: [email protected] Page 15 of 15 Data Sheet Sep/04