U2270B

Features • • • • • • • • • Carrier Frequency fosc 100 kHz to 150 kHz Typical Data Rate up to 5 Kbaud at 125 kHz Suitable for Manchester and Bi-phase Modulation Power Supply from the Car Battery or from 5V Regulated Voltage Optimized for Car Immobilizer Applications Tuning Capability Microcontroller-compatible Interface Low Power Consumption in Standby Mode Power-supply Output for Microcontroller Applications • • • • Car Immobilizers Animal Identification Access Control Process Control Read/Write Base Station U2270B 1. Description The U2270B is an IC for IDIC® read/write base stations in contactless identification and immobilizer systems. The IC incorporates the energy-transfer circuit to supply the transponder. It consists of an on-chip power supply, an oscillator, and a coil driver optimized for automotive-specific distances. It also includes all signal-processing circuits which are necessary to transform the small input signal into a microcontroller-compatible signal. 4684E–RFID–02/08 Figure 1-1. System Block Diagram Transponder/TAG Read/write base station Osc Transponder IC RF field typ. 125 kHz U2270B NF read channel Carrier enable MCU Data output Unlock System Figure 1-2. Block Diagram DVS VEXT VS VBatt Standby Power supply COIL1 =1 MS CFE COIL2 Driver DGND & Oscillator Frequency adjustment RF Amplifier Input Lowpass filter Schmitt trigger Output & HIPASS GND OE 2 U2270B 4684E–RFID–02/08 U2270B 2. Pin Configuration Figure 2-1. Pinning GND OUTPUT OE INPUT MS CFE DGND COIL2 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 HIPASS RF VS STANDBY VBATT DVS VEXT COIL1 Table 2-1. Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Pin Description Symbol GND OUTPUT OE INPUT MS CFE DGND COIL2 COIL1 VEXT DVS VBatt STANDBY VS RF HIPASS Function Ground Data output Data output enable Data input Mode select coil 1: common mode/differential mode Carrier frequency enable Driver ground Coil driver 2 Coil driver 1 External power supply Driver supply voltage Battery voltage Standby input Internal power supply (5V) Frequency adjustment DC decoupling 3 4684E–RFID–02/08 3. Functional Description 3.1 Power Supply (PS) Figure 3-1. Equivalent Circuit of Power Supply and Antenna Driver DVS VEXT VS VBatt Standby Internal supply 9V 25 kΩ 12 kΩ 6V PS COILx 6V 18V DRV DGND The U2270B can be operated with one external supply voltage or with two externally-stabilized supply voltages for an extended driver output voltage or from the 12V battery voltage of a vehicle. The 12V supply capability is achieved via the on-chip power supply (see Figure 3-1). The power supply provides two different output voltages, VS and VEXT. VS is the internal power supply voltage for everything except for the driver circuit. Pin VS is used to connect a block capacitor. VS can be switched off by the STANDBY pin. In standby mode, the chip’s power consumption is very low. VEXT is the supply voltage of the antenna’s pre-driver. This voltage can also be used to operate external circuits, such as a microcontroller. In conjunction with an external NPN transistor, it also establishes the supply voltage of the antenna coil driver, DVS. 4 U2270B 4684E–RFID–02/08 U2270B 3.2 Operation Modes to Power the U2270B The following section explains the three different operation modes to power the U2270B. 3.2.1 One-rail Operation All internal circuits are operated from one 5V power rail (see Figure 3-2). In this case, VS, VEXT and DVS serve as inputs. VBatt is not used but should also be connected to that supply rail. Figure 3-2. One-rail Operation Supply + +5V (stabilized) DVS VEXT VS VBatt Standby 3.2.2 Two-rail Operation In this application, the driver voltage, DVS, and the pre-driver supply, VEXT, are operated at a higher voltage than the rest of the circuitry to obtain a higher driver-output swing and thus a higher magnetic field (see Figure 3-3). VS is connected to a 5V supply, whereas the driver voltages can be as high as 8V. This operation mode is intended to be used in situations where an extended communication distance is required. Figure 3-3. Two-rail Operation Supply 7V to 8V (stabilized) + + 5V (stabilized) DVS VEXT VS VBatt Standby 3.2.3 Battery-voltage Operation Using this operation mode, VS and VEXT are generated by the internal power supply (see Figure 3-4 on page 6). For this mode, an external voltage regulator is not needed. The IC can be switched off via the STANDBY pin. VEXT supplies the base of an external NPN transistor and external circuits, like a microcontroller (even in standby mode). Pin VEXT and VBatt are overvoltage protected via internal Zener diodes (see Figure 3-1 on page 4).The maximum current into the pins is determined by the maximum power dissipation and the maximum junction temperature of the IC. 5 4684E–RFID–02/08 Figure 3-4. Battery Operation 7V to 16V DVS VEXT VS VBatt Standby Table 3-1. Characteristics of the Various Operation Modes External Components Required 1 voltage regulator 1 capacitor 2 voltage regulators 2 capacitors 1 transistor 2 capacitors Optional, for load dump protection: 1 resistor 1 capacitor Supply-voltage Range 5V ±10% 5V ±10% 7V to 8V Driver Output Voltage Swing ≈ 4V 6V to 7V Standby Mode Available No No Operation Mode One-rail operation Two-rail operation Battery-voltage operation 6V to 16V ≈ 4V Yes 3.3 Oscillator (Osc) The frequency of the on-chip oscillator is controlled by a current fed into the RF input. An integrated compensation circuit ensures a wide temperature range and a supply-voltage– independent frequency which is selected by a fixed resistor between RF (pin 15) and VS (pin 14). For 125 kHz, a resistor value of 110 kΩ is defined. For other frequencies, use the following formula: 14375 R t [ k Ω] = --------------------- – 5 f 0 [ kHz ] This input can be used to adjust the frequency close to the resonance of the antenna. For more details see Section “Applications” on page 10. Figure 3-5. Equivalent Circuit of Pin RF VS Rf RF 2 kΩ 6 U2270B 4684E–RFID–02/08 U2270B 3.4 Low-pass Filter (LPF) The fully integrated low-pass filter (4th-order Butterworth) removes the remaining carrier signal and high-frequency disturbances after demodulation. The upper cut-off frequency of the LPF depends on the selected oscillator frequency. The typical value is fOsc / 18, and data rates up to fOsc / 25 are possible if bi-phase or Manchester encoding is used. A high-pass characteristic results from the capacitive coupling at the input pin 4 as shown in Figure 3-6. The input voltage swing is limited to 2 Vpp. For frequency response calculation, the impedances of the signal source and LPF input (typical 210 kΩ) have to be considered. The recommended values of the input capacitor for selected data rates are given in Section 4., “Applications” , on page 10. Note: After switching on the carrier, the DC voltage of the coupling capacitor changes rapidly. When the antenna voltage is stable, the LPF needs approximately 2 ms to recover full sensitivity. Figure 3-6. Equivalent Circuit of Pin Input VBias + 0.4V RS CIN Input 10 kΩ 210 kΩ VBias - 0.4V 3.5 Amplifier (AMP) The differential amplifier has a fixed gain, typically 30. The HIPASS pin is used for DC decoupling. The lower cut-off frequency of the decoupling circuit can be calculated as follows: 1 f cut = -------------------------------------------2 × π × C HP × R i The value of the internal resistor Ri can be assumed to be 2.5 kΩ. Recommended values of CHP for selected data rates can be found in Section 4., “Applications” , on page 10. 7 4684E–RFID–02/08 Figure 3-7. Equivalent Circuit of Pin HIPASS R + LPF VRef R Ri R R Schmitt trigger HIPASS CHP 3.6 Schmitt Trigger The signal is processed by a Schmitt trigger to suppress possible noise and to make the signal microcontroller-compatible. The hysteresis level is 100 mV symmetrically to the DC operation point. The open-collector output is enabled by a low level at OE (pin 3). Figure 3-8. Equivalent Circuit of Pin OE 7 µA OE 8 U2270B 4684E–RFID–02/08 U2270B 3.7 Driver (DRV) The driver supplies the antenna coil with the appropriate energy. The circuit consists of two independent output stages. These output stages can be operated in two different modes. In common mode, the outputs of the stages are in phase; in this mode, the outputs can be interconnected to achieve a high-current output capability. Using the differential mode, the output voltages are in anti-phase; thus, the antenna coil is driven with a higher voltage. For a specific magnetic field, the antenna coil impedance is higher for the differential mode. As a higher coil impedance results in better system sensitivity, the differential mode should be preferred. The CFE input is intended to be used for writing data into a read/write or a crypto transponder. This is achieved by interrupting the RF field with short gaps. The various functions are controlled by the inputs MS and CFE (see “Function Table” on page 10). The equivalent circuit of the driver is shown in Figure 3-1 on page 4. Figure 3-9. Equivalent Circuit of Pin MS 30 µA MS Figure 3-10. Equivalent Circuit of Pin CFE 30 µA CFE 9 4684E–RFID–02/08 3.8 Function Table CFE Low Low High High MS Low High Low High COIL1 High Low COIL2 High High OE Low High Output Enabled Disabled STANDBY Low High U2270B Standby mode Active 4. Applications To achieve the system performance, consider the power-supply environment and the magnetic-coupling situation. The selection of the appropriate power-supply operation mode depends on the quality of supply voltage. If an unregulated supply voltage in the range of V = 7V to 16V is available, the internal power supply of the U2270B can be used. In this case, standby mode can be used and an external low-current microcontroller can be supplied. If a 5V supply rail is available, it can be used to power the U2270B. In this case, check that the voltage is noise-free. An external power transistor is not necessary. The application also depends on the magnetic-coupling situation. The coupling factor mainly depends on the transmission distance and the antenna coils. The following table lists the appropriate application for a given coupling factor. The magnetic coupling factor can be determined using Atmel®’s test transponder coil. Table 4-1. Magnetic Coupling Magnetic Coupling Factor k > 3% k > 1% k > 0.5% k > 0.3% Appropriate Application Free-running oscillator Diode feedback Diode feedback plus frequency altering Diode feedback plus fine frequency tuning The maximum transmission distance is also influenced by the accuracy of the antenna’s resonance. Therefore, the recommendations given above are proposals only. A good compromise for the resonance accuracy of the antenna is a value in the range of fres = 125 kHz ± 3%. Further details concerning the adequate application and the antenna design is provided in Section “Antenna Design Hints”. 10 U2270B 4684E–RFID–02/08 U2270B The application of the U2270B includes the two capacitors CIN and CHP whose values are linearly dependent on the transponder’s data rate. The following table gives the appropriate values for the most common data rates. The values are valid for Manchester and bi-phase code. Table 4-2. Recommended Capacitor Values Input Capacitor (CIN) 680 pF 1.2 nF Decoupling Capacitor (CHP) 100 nF 220 nF Data Rate f = 125 kHz f / 32 = 3.9 Kbits/s f / 64 = 1.95 Kbits/s The following applications are typical examples. The values of CIN and CHP correspond to the transponder’s data rate only. The arrangement to fit the magnetic-coupling situation is also independent of other design issues except for one constellation. This constellation, consisting of diode feedback plus fine frequency tuning together with the two-rail power supply, should be used if the transmission distance is d ≈ 10 cm. 4.1 Application 1 Application using few external components. This application is for intense magnetic coupling only. Figure 4-1. Application Circuit 1 110 kΩ 5V + 47 nF 47 µF VBatt DVS RF VEXT VS VDD U2270B INPUT CIN 1N4148 R 470 kΩ 1.5 nF COIL2 1.2 nF DGND GND 1.35 mH COIL1 MS CFE OE Microcontroller STANDBY OUTPUT HIPASS CHP VSS 11 4684E–RFID–02/08 4.2 Application 2 Basic application using diode feedback. This application allows higher communication distances than .“Application 1” Figure 4-2. Application Circuit 2 BC639 4× 1N4148 + 68 kΩ + + 75 kΩ 100 kΩ 4.7 nF 43 kΩ 22 µF 22 µF VS RF 1.2 nF COIL2 1.35 mH Antenna CIN 1.5 nF CHP Input HIPASS DGND GND Output OE VSS I/O 82Ω COIL1 CFE VEXT DVS VBatt MS VDD GND 22 µF 360Ω 12V U2270B Standby Microcontroller 1N4148 470 kΩ 12 U2270B 4684E–RFID–02/08 U2270B 4.3 Application 3 This application is comparable to “Application 2” but alters the operating frequency. This allows higher antenna resonance tolerances and/or higher communication distances. This application is preferred if the detecting microcontroller is close to the U2270B, as an additional microcontroller signal controls the adequate operating frequency. Figure 4-3. Application Circuit 3 4× 1N4148 68 kΩ + 75 kΩ 100 kΩ 4.7 nF 43 kΩ 22 µF 47 nF 5V VS RF VEXT DVS VBatt MS CFE VDD GND 1 nF COIL2 1.5 mH Antenna CIN 470 kΩ 1.5 nF 4.7 kΩ BC846 1.5 kΩ CHP Input HIPASS 180 pF 100Ω DGND GND Output OE VSS 82Ω COIL1 U2270B Standby Microcontroller 1N4148 Note: Application examples have not been examined for series production or reliability, and no worst case scenarios have been developed. Customers who adapt any of these proposals must carry out their own testing and be convinced that no negative consequences arise from the proposals. 13 4684E–RFID–02/08 5. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. All voltages are referred to GND (Pins 1 and 7) Parameter Operating voltage Operating voltage Range of input and output voltages Output current Output current Driver output current Power dissipation SO16 Junction temperature Storage temperature Ambient temperature Pin 12 8, 9, 10, 11, 14 3, 4, 5, 6, 15, 16 2 and 13 10 2 8 and 9 Symbol VBatt VS, VEXT, DVS, Coil 1, Coil 2 VIN VOUT IEXT IOUT ICoil Ptot Tj Tstg Tamb –55 –40 Min. VS –0.3 –0.3 –0.3 Max. 16 8 VS + 0.3 VBatt 10 10 200 380 150 125 105 Unit V V V mA mA mA mW °C °C °C 6. Thermal Resistance Parameter Thermal resistance SO16 Symbol RthJA Value 120 Unit K/W 7. Operating Range All voltages are referred to GND (Pins 1 and 7) Parameter Operating voltage Operating voltage Operating voltage Carrier frequency Pin 12 14 10, 11 Symbol VBatt VS VEXT, DVS Value 7 to 16 4.5 to 6.3 4.5 to 8 100 to 150 Unit V V V kHz 14 U2270B 4684E–RFID–02/08 U2270B 8. Electrical Characteristics All voltages are referred to GND (Pins 1 and 7) Parameters Data output - Collector emitter - Saturation voltage Data output enable - Low-level input voltage - High-level input voltage Data input - Clamping level low - Clamping level high - Input resistance - Input sensitivity Driver polarity mode - Low-level input voltage - High-level input voltage Carrier frequency enable - Low-level input voltage - High-level input voltage 5V application without load connected to the coil driver 12V application Test Conditions Iout = 5 mA Pin 2 Symbol VCEsat Min. Typ. Max. 400 Unit mV 3 Vil Vih Vil Vih Rin SIN Vil Vih Vil Vih IS ISt VS dVs/dT IS VDRV VDRV VEXT dVEXT/dT IEXT IEXT Vil Vih f0 fcut 0.5 2.4 2 3.8 220 10 V V V V kΩ mVpp V V V V f = 3 kHz (square wave) Gain capacitor = 100 nF 4 5 2.4 0.2 6 10, 11, 12 and 14 12 3.0 0.8 Operating current 4.5 9 mA Standby current VS - Supply voltage - Supply voltage drift - Output current Driver output voltage - One-rail operation - Battery-voltage operation VEXT - Output voltage - Supply voltage drift - Output current - Standby output current Standby input - Low-level input voltage - High-level input voltage Oscillator - Carrier frequency Low-pass filter - Cut-off frequency Amplifier gain Note: 30 4.6 1.8 2.9 3.1 4.6 3.5 0.4 5.4 4.2 3.5 3.6 4.0 5.4 4.2 70 6.3 µA V mV/K mA VPP VPP V mV/K mA mA V V kHz kHz 14 IL = ±100 mA VS, VEXT, VBatt, DVS = 5V VBatt = 12V 8, 9 4.3 4.7 6.3 10 IC active Standby mode 13 RF resistor = 110 kΩ (“Application 2” ), REM 1(1) Carrier frequency = 125 kHz CHP = 100 nF 0.8 3.1 121 125 7 30 129 1. REM 1: In “Application 1” where the oscillator operates in free-running mode, the IC must be soldered free from distortion. Otherwise, the oscillator may be out of bounds. 15 4684E–RFID–02/08 9. Ordering Information Extended Type Number U2270B-MFPY U2270B-MFPG3Y Package SO16 SO16 Remarks Tube, Pb-free Taped and reeled, Pb-free 10. Package Information Package: SO 16 Dimensions in mm 9.9±0.1 5±0.2 3.7±0.1 0.2 0.1+0.15 1.4 0.4 1.27 8.89 3.8±0.1 6±0.2 16 9 technical drawings according to DIN specifications 1 Pin 1 identity 8 Drawing-No.: 6.541-5031.02-4 Issue: 1; 15.08.06 16 U2270B 4684E–RFID–02/08 U2270B 11. Revision History Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. Revision No. History • Put datasheet in a new template • Section 3.4 “Low-pass Filter (LPF) on page 7: Typo removed • Section 8 “Electrical Characteristics” on page 15: Parameter VS alignment corrected • • • • • • • • Put datasheet in a new template Pb-free logo on page 1 deleted Section 10 “Package Information” on page 16 changed Minor grammatical corrections and fixed broken cross references Put datasheet in a new template Pb-free Logo on page 1 added New heading rows on Table “Absolute Maximum Ratings” on page 14 added Ordering Information on page 16 changed 4684E-RFID-01/08 4684D-RFID-09/06 4684C-RFID-12/05 • Last page: Legal sentence changed 4684B-RFID-09/05 17 4684E–RFID–02/08 Headquarters Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 International Atmel Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-en-Yvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Product Contact Web Site www.atmel.com Technical Support rfid@atmel.com Sales Contact www.atmel.com/contacts Literature Requests www.atmel.com/literature Disclaimer: T he information in this document is provided in connection with Atmel products. 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