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| U2741B UHF ASK/FSK Transmitter Description The U2741B is a PLL transmitter IC which has been specially developed for the demands of RF low-cost data transmission systems at data rates up to 20 kBaud. The transmitting frequency range is 300 MHz to 450 MHz. It can be used in both FSK and ASK systems. Electrostatic sensitive device. Observe precautions for handling. Features D One-chip solution with minimum external circuitry D Lower cost than the usual discrete solutions using SAW and transistors D Very small SSO16 package, pitch 0.635, 150 mil D Supply voltage 2.0 V to 5.5 V in the temperature range -20C to 70C Supply voltage 2.2 V to 5.5 V in the temperature range -40C to 85C D "Single-Ended Open-Collector" output (same antennas can be used as in discrete solutions, simpler adaptation of magnetic loop antennas) D XTO output for clocking the mC, thereby together with M44C090 or M44C890 the optimum system cost-effectiveness D Very large FSK frequency deviation achievable by 100 ppm pulling of the reference crystal D Very high transmitting frequency accuracy compared to SAW solutions. This enables receivers at lower bandwidth than is possible with SAW resonators. D ESD protection according to MIL-STD.883 (4KV HBM) except Pins XTO1/ 2, ANT and LF System Block Diagram UHF ASK/FSK Remote control transmitter UHF ASK/FSK Remote control receiver 1 Li cell U2741B PLL U3741BM Demod. Control 1...3 mC Keys Encoder M44Cx9x XTO IF Amp Antenna Antenna VCO PLL XTO Power amp. LNA VCO Figure 1. System block diagram Order Information Extended Type Number U2741B-MFB U2741B-MFBG3 U2741B-NFB Package SSO16 SSO16 SSO16 Tube Taped and reeled Tube, optimized power-supply rejection, value of C4 differs from M-version, enhanced XTO stability Taped and reeled, see above Remarks U2741B-NFBG3 SSO16 Rev. A2, 22-Dec-00 1 (7) U2741B Pin Description Pin ASK 1 FSK VCC CLK GND 2 3 4 16 15 14 13 DIVIC PWRSET PWRVCC ANT PWRGND1 Symbol ASK FSK VCC CLK GND LFVCC LFGND LF XTO2 XTO1 Function Modulation input ASK Modulation input FSK Supply voltage Clock output Ground Supply voltage VCO VCO ground Circuit PLL loop FM modulation output Connection for crystal 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 U2741B 5 12 11 10 9 LFVCC 6 LFGND 7 LF 8 PWRGND2 PWRGND2 Power GND2 PWRGND1 Power GND1 ANT PWRVCC PWRSET DIVIC RF output Supply voltage power amplifier Applied to VCC Pitch factor setting for crystal L: high crystal frequency; H: low crystal frequency XTO1 XTO2 Figure 2. Pinning SSO16 Block Diagram ASK OR DIVC FSK PWRSET Power up VCC PWRVCC VCO CLK PA ANT GND f 64 PWRGND1 LFVCC f n PWRGND2 XTO XTO1 LFGND LF XTO2 U2741B Figure 3. Block diagram 2 (7) Rev. A2, 22-Dec-00 U2741B General Description The fully integrated VCO and the "single-ended opencollector" output allow particularly simple, low-cost RF miniature transmitters to be assembled. The single-ended output enables a considerably simplified adaptation of both a magnetic loop antenna of any form or a l/4 antenna. This is because the load impedance must not be balanced as would be the case with a differential output. The XTO's frequency can be selected at either 13.56 MHz (USA 9.844 MHz) or 6.78 MHz (USA 4.9219 MHz). Thus, it is possible to use not only exceptionally small SMD crystals at 13.56 MHz but also very low-cost 6.78-MHz crystals in a wired metal package (e.g. in the HC49S housing). The frequency is selected by connecting PIN16 (DIVC) to either GND or VS. Application Circuit The following component values are recommendations for a typical application. C5, C6, C7 are block capacitors. The values of these capacitors depend on the board layout. C5 = 1 nF, C6 = 1 nF, C7 = 22 nF are typically used here. For C5, the impedance between f = 100 MHz and f = 1 GHz should be as low as possible. C3 is not needed in ASK transmitter applications. In the case of FSK, C3 is selected in such a way that the desired transmission frequency deviation is achieved (typ. 30 kHz). The capacitance here depends upon the crystal's load capacity (C4) recommended by the manufacturer of the crystal. C2 = 3.9 nF, C1 = 15 nF, R4 = 220 W. CLoop1, CLoop2 are selected so that the antenna oscillates in resonance and the adaptation to the appropriate impedance transformation is possible. LFeed is an inductor for the antenna's DC current supply. A typical value is LFeed = 220 nH. LFeed can be either printed on the PC_Board or be a discrete component. Further information regarding the application is provided in the description of the "RKE Design Kit (U2741B, U3741B)" in chapter 2.2.2. This chapter labeled "Application Hints U2741B" also describes the antenna design in more detail. At high frequencies, crystals have a very fast start-up time (< 1.5 ms at 13.56 MHz, < 3 ms at 6.78 MHz), whereby a wait time of 5 to 10 ms is required until the transmitter IC is locked. This means that the processor does not need to poll a lock detect output. Functional Description The IC can be switched on at both the FSK and the ASK input. The IC's ChipSelect is performed by the logical OR operation of ASK and FSK input. In the case of VFSK , V ASK 0.3 V, the power-down supply current is ISoff < 0.35 A. The ASK input activates the power amplifier and the PLL. The FSK input only activates the PLL and, if capacitor C3 is installed, pulls the crystal to the lower frequency, whereby the transmitter is FSK modulated. After switching on at FSK, the VCO locks onto the 32 or 64 times higher frequency of the crystal oscillator. Output Power Measurement The following output network (see figure 4) can be used for output power evaluation, the exact values of L10, C10 are dependent on the layout. L10, C10 is the transformation network to adopt the output impedance of the IC to 50 W. The following table shows the values for an output power of 2 mW and an RPWRSET = 1.2 kW. f/ MHz 315 433.92 C10/ pF 2.7 1.8 VS PWRVCC L10 ANT C10 50 W 15009 FSK Transmission The U2741B is switched on by VFSK = VS. 5 ms later, VS is applied to VASK. The output can then be modulated by means of Pin FSK. This is done by connecting capacitor C3 in parallel to the load capacitor C4. L10/ nH 56 33 ZLoad_opt/ W 260 + j330 185 + j268 ASK Transmission The U2741B is activated by VFSK = VS. VASK remains 0 V for 5 ms, then the output power can be modulated by means of Pin ASK. In this case, VFSK remains = VS during the message, the capacitor C3 is not mounted. Take-Over of the Clock Pulse in the C The clock of the crystal oscillator can be used for clocking the C. The M44C090 and M44C890 have the special feature of starting with an integrated RC oscillator to switch on the U2741B with VFSK = VS. 5 ms later, the 3.39-MHz clock frequency is present, so that the message can be sent with crystal accuracy. ZLoad-opt Figure 4. Measurement output network Rev. A2, 22-Dec-00 3 (7) U2741B +VS= 2.0...5.5V ASK FSK ASK 1 FSK 2 VCC 3 CLK 4 GND 5 LFVCC 6 LFGND 7 R4 C1 LF 8 OR Power up VCO f 64 f n XTO PA DIVC 16 PWRSET 15 PWRVCC 14 ANT 13 PWRGND1 12 PWRGND2 11 XTO1 10 XTO2 9 C3 13.56MHz CLoop2 RPWRSET LFeed C7 CLK 3.39MHz C5 CLoop1 C6 C4 U2741B C2 Antenna Figure 5. Application circuit Absolute Maximum Ratings Parameters Supply voltage Power dissipation Junction temperature Storage temperature Ambient temperature Symbol VS Ptot Tj Tstg Tamb Min. Typ. Max. 6 250 150 125 105 Unit V mW C C C -55 -40 Thermal Resistance Parameters Junction ambient Symbol RthJA Value 180 Unit K/W 4 (7) Rev. A2, 22-Dec-00 U2741B Electrical Characteristics All parameters are refered to GND (Pin 5). The possible operating ranges refer to different circuit conditions: VS = 2.0 V to 5.5 V @ Tamb = -20C to +70C, VS = 2.2 V to 5.5 V @ Tamb = -40C to +85C (Typ. 25C, 3 V) Parameters Supply current (power up, output OFF) Supply current (power up, output ON) Output power Test Conditions / Pins VASK = GND, VFSK = VS, Vs = 3 V VASK = VS, VS = 3 V RPWRSET = 1.2 kW VS = 3 V, Tamb = 25C, f = 433.92 MHz RPWRSET = 1.2 kW RPWRSET = 1.8 kW Symbol ISoff ISon IStransmit 10 12.5 4.7 Min. Typ. Max. 0.35 6.2 Unit A mA mA Supply current (power down) VASK, VFSK v 0.3 V, VS < 3.6 V PRef PRef DPRef DPRef DPRef DPRef 1.5 -0.5 3 1 5 3 -1.5 -4.0 dBm dBm dB dB Output power variation for the full temperature range Tamb = -40C to +85C, f = 433.92 MHz, VS = 3.0 V VS = 2.4 V Tamb = -20C to +85C, f = 433.92 MHz, VS = 2.0 V Pout = PRef + DPRef -5.5 dB Output power variation for f = 315 MHz compared to f = 433.92 MHz Maximum peak output antenna voltage f = 315 MHz 1.5 dB Pout = PRef + DPRef @Pout = 2.0 mW, The load impedance must be selected to meet the Vout maximum requirement. The supply current is not dependent on the load impedance tolerance. Voutmax VS - 0.7 V V(peak) Spurious emission @ Tamb = 25C fo n x fPC (fPC = 6.78 MHz) Load capacitance at CLK 3 pF f = 230 MHz to 470 MHz f < 230 MHz, f > 470 MHz M-version: @ Tamb = 25C N-version: full temperature range (monitoring) Crystal frequency = 13.56 MHz Em Em -40 -58 dBC dBC Oscillator frequency XTO fXTO fXTO 13.56 - 30 ppm 6.78 -30 ppm 13.56 13.56 +30 ppm 6.78 +30 ppm MHz 6.78 MHz load capacity of the crystal must be selected accordingly Loop bandwidth For best LO noise Loop filter components: C2 = 3.9 nF, C1 = 15 nF, R4 = 220 W Referring to the phase comparator fPC = 6.78 MHz @ 1 MHz @ 36 MHz 6.78 MHz BLoop 100 kHz Phase noise PLL Phase noise VCO Frequency range of the VCO Clock output (CMOS C compatible) PNPLL PNVCO PNVCO fVCO Clkout 300 -111 -91 -123 fout/128 -105 -87 -119 450 dBC/Hz dBC/Hz MHz MHz Rev. A2, 22-Dec-00 5 (7) U2741B Electrical Characteristics (continued) All parameters are refered to GND (Pin 5). The possible operating ranges refer to different circuit conditions: VS = 2.0 V to 5.5 V @ Tamb = -20C to +70C, VS = 2.2 V to 5.5 V @ Tamb = -40C to +85C (Typ. 25C, 3 V) Parameters Load capacitance at CLK Series resonance R of the crystal fXTO = 13.56 MHz fXTO = 9.84 MHz fXTO = 6.78 MHz fXTO = 4.90 MHz Duty cycle of the modulation signal = 50% Duty cycle of the modulation signal = 50% VCLK = 0.2 x VS VCLK = 0.3 x VS VCLK = 0.8 x VS VCLK = 0.7 x VS Test Conditions / Pins Symbol CCLK Rs Rs Rs Rs fmodFSK fmodASK 0 0 Min. Typ. Max. 10 80 100 150 225 20 20 Unit pF W FSK modulation frequency rate ASK modulation frequency rate CLK output - Output current Low - Output current Low - Output current High - Output current High ASK input - Low level input voltage - High level input voltage - Input current High FSK input - Low level input voltage - High level input voltage - Input current High kHz kHz Iol Iol Ioh Ioh VASKl VASKh IASKh VFSKl VFSKh IFSKh 150 200 -150 -200 100 0.3 mA mA mA mA V V mA V V mA 1.7 140 0.3 1.7 140 Package Information Package SSO16 Dimensions in mm 5.00 max 5.00 4.80 1.40 0.2 0.25 0.635 4.45 16 9 0.25 0.10 3.95 max 5.2 4.8 6.2 5.8 technical drawings according to DIN specifications 13045 1 8 6 (7) Rev. A2, 22-Dec-00 U2741B Ozone Depleting Substances Policy Statement It is the policy of Atmel Germany GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances (ODSs). The Montreal Protocol (1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. Atmel Germany GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2. Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency (EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively. Atmel Germany GmbH can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances. 8. We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use Atmel Wireless & Microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. Data sheets can also be retrieved from the Internet: http://www.atmel-wm.com Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423 Rev. A2, 22-Dec-00 7 (7) |
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