Features • Very High Transmitting Frequency Accuracy Compared to SAW Solutions (Enables Receivers at Lower Bandwidth than with SAW Resonators) • Lower Cost than the Usual Discrete Solutions Using SAW and Transistors • Supply Voltage 2.2 V to 4.0 V in the Temperature Range of -40°C to 85°C • XTO Output for Clocking the Microcontroller, Thereby Together with the ATAR090 or ATAR890 Results in the Optimum System Cost-effectiveness • One-chip Solution with Minimum External Circuitry • Very Small SSO16 Package, Pitch 0.635, 150 mil • “Single-ended Open-collector” Output (Same Antennas Can Be Used as in Discrete Solutions, Simpler Adaptation of Magnetic Loop Antennas) • ESD Protection According to MIL-STD.883 (4 KV HBM) Except Pins XTO1/ 2, ANT and LF Electrostatic sensitive device. Observe precautions for handling. UHF ASK Transmitter U2745B Description The U2745B is a PLL transmitter IC which has been especially developed for the demands of RF low-cost data transmission systems at data rates up to 20 kBaud. The transmitting frequency range is 310 MHz to 440 MHz. It can be used in ASK systems. The main applications of the U2745B are in the areas of outside temperature metering, socket control, garage door opener, consumption metering, light/fan or aircondition control, jalousies, wireless keyboard and various other consumer market applications. Rev. 4734A–RKE–11/03 Figure 1. System Block Diagram UHF ASK Remote control transmitter UHF ASK Remote control receiver 1 Li cell Demod. Keys Encoder ATARx9x Control PLL 1...3 Microcontroller U3745BM U2745B IF Amp Antenna Antenna XTO VCO PLL Power amp. LNA XTO VCO Figure 2. Block Diagram ASK GND OR EN PWRSET Power up PWRVCC VCC VCO PA ANT CLK f PWRGND1 GND 64 LFVCC PWRGND2 f XTO n LFGND XTO1 LF NC U2745B 2 U2745B 4734A–RKE–11/03 U2745B Pin Configuration Figure 3. Pinning SSO16 ASK 1 16 GND EN 2 15 PWRSET VCC 3 14 PWRVCC CLK 4 13 ANT GND 5 12 PWRGND1 LFVCC 6 11 PWRGND2 LFGND 7 10 XTO1 LF 8 9 NC U2745B Pin Description Pin Symbol 1 ASK Function Modulation input ASK 2 EN 3 VCC Supply voltage Enable input 4 CLK Clock output 5 GND Ground 6 LFVCC Supply voltage VCO 7 LFGND VCO ground 8 LF Circuit PLL loop 9 NC Not connected 10 XTO1 11 PWRGND2 Connection for crystal Power GND2 12 PWRGND1 Power GND1 13 ANT 14 PWRVCC Supply voltage power amplifier 15 PWRSET Applied to VCC 16 GND RF output Ground 3 4734A–RKE–11/03 General Description The fully integrated VCO and the “single-ended open-collector” 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 to be either 13.56 MHz or 9.844 MHz (USA). At these frequencies, crystals have a very fast start-up time (< 1.5 ms), 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 ASK Transmission The U2745B is activated by EN = VS. VASK must remain 0 V for 5 ms, then the output power can be modulated by means of pin ASK. VEN remains = VS during the transmission of the message. The ASK input activates the power amplifier and the PLL. Take-over of the Clock Pulse in the Microcontroller The clock of the crystal oscillator can be used for clocking the microcontroller. The ATAR090 and ATAR890 have the special feature of starting with an integrated RC oscillator to switch on the U2745B with VEN = VS. 5 ms later, the 3.39-MHz clock frequency is present, so that the message can be sent with crystal accuracy. Application Circuit The following component values are recommendations for a typical application. C4, C5, and C6 are block capacitors. The values of these capacitors depend on the board layout. C4 = 1 nF, C5 = 1 nF, and C6 = 22 nF are typically used here. For C5, the impedance between f = 100 MHz and f = 1 GHz should be as low as possible. CLoop1 and CLoop2 are selected so that the antenna oscillates in resonance and the adaptation to the appropriate impedance transformation is possible. L F e e d 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. Output Power Measurement The following output network (see Figure 4 on page 5) can be used for output power evaluation, the exact values of L10 and C10 are dependent on the layout. L10 and C10 form 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. Table 1. Transformation Network 4 f/MHz C10/pF L10/nH ZLoad_opt/W 315 2.7 56 260 + j330 433.92 1.8 33 185 + j268 U2745B 4734A–RKE–11/03 U2745B Figure 4. Measurement Output Network VS PWRVCC L10 ZLoad-opt ANT C10 50 W Figure 5. Application Circuit +VS = 2.2 ... 4.0 V ASK ASK 1 GND 16 OR EN EN PWRSET 15 2 VCC 3 C6 CLK CLK Power up PWRVCC VCO PA 6 n 7 R4 8 C2 PWRGND2 11 f LFGND CLoop1 12 64 LFVCC LF LFeed C4 PWRGND1 f 5 C1 ANT 13 GND C5 R PWRSET 14 4 3.39 MHz CLoop2 XTO XTO1 13.56 MHz 10 U2745B NC C3 9 Antenna 5 4734A–RKE–11/03 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. Parameters Max. Unit Supply voltage Symbol VS 6 V Power dissipation Ptot 250 mW Tj 150 °C Junction temperature Min. Storage temperature Tstg -55 125 °C Ambient temperature Tamb -40 85 °C Thermal Resistance Parameters Junction ambient Symbol Value Unit RthJA 180 K/W Electrical Characteristics All parameters are refered to GND (pin 5), VS = 3 V, Tamb = 25°C, unless otherwise specified The possible operating ranges refer to different circuit conditions: VS = 2.2 V to 4.0 V at Tamb = -40°C to +85°C Parameters Test Conditions Supply current (power down) VASK, VFSK £ 0.3 V, VS < 3.6 V Supply current (power up, output OFF) VASK = GND, VEN = VS, VS = 3 V Supply current (power up, output ON) VASK = VS, VS = 3 V, RPWRSET = 1.2 kW Output power Output power variation for f = 315 MHz compared to f = 433.92 MHz VS = 3 V, Tamb = 25°C, f = 433.92 MHz RPWRSET = 1.2 kW f = 315 MHz Pout = PRef + DPRef Symbol Typ. Max. Unit ISoff 2 10 µA ISon 4.7 6.2 mA IStransmit 10 12.5 mA 3 5 dBm PRef Min. 1 DPRef 1.5 dB Voutmax VS - 0.7 V V(peak) Maximum peak output antenna voltage at 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 Spurious emission fo ±(n ´ fPC) where fPC = 6.78 MHz Load capacitance at CLK £ 3 pF f = 230 MHz to 470 MHz f < 230 MHz, f > 470 MHz Em Em Oscillator frequency XTO Crystal frequency = 13.56 MHz fXTO Loop bandwidth For best LO noise Loop filter components: C2 = 3.9 nF, C1 = 15 nF, R4 = 220 W BLoop 100 Phase noise PLL Referring to the phase comparator fPC = 6.78 MHz PNPLL -111 Phase noise VCO at 1 MHz at 36 MHz PNVCO PNVCO -90 -122 6 13.56 30 ppm 13.56 -40 -58 dBC dBC 13.56 + 30 ppm MHz kHz -105 dBC/Hz dBC/Hz U2745B 4734A–RKE–11/03 U2745B Electrical Characteristics (Continued) All parameters are refered to GND (pin 5), VS = 3 V, Tamb = 25°C, unless otherwise specified The possible operating ranges refer to different circuit conditions: VS = 2.2 V to 4.0 V at Tamb = -40°C to +85°C Parameters Test Conditions Symbol Min. 310 Typ. Max. Unit 440 MHz Frequency range of the VCO fVCO Clock output (CMOS microcontroller compatible) Clkout Load capacitance at CLK CCLK 10 pF Rs Rs 80 100 W 20 kHz 100 µA µA µA µA Series resonance R of the crystal fXTO = 13.56 MHz fXTO = 9.84 MHz ASK modulation frequency rate Duty cycle of the modulation signal = 50% fout/128 fmodASK 0 Iol Iol Ioh Ioh 150 200 -150 -200 ASK input - Low level input voltage - High level input voltage - Input current High VASKl VASKh IASKh 1.7 Enable ASK - Low level input voltage - High level input voltage - Input current High VEN VFSKl VFSKh IFSKh CLK output - Output current Low - Output current Low - Output current High - Output current High VCLK = 0.2 ´ VS VCLK = 0.3 ´ VS VCLK = 0.8 ´ VS VCLK = 0.7 ´ VS MHz 0.3 140 0.3 1.7 140 V V µA V V µA 7 4734A–RKE–11/03 Ordering Information Extended Type Number Package Remarks U2745B-MFB SSO16 Tube U2745B-MFBG3 SSO16 Taped and reeled Package Information 8 U2745B 4734A–RKE–11/03 Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Regional Headquarters Europe Atmel Sarl Route des Arsenaux 41 Case Postale 80 CH-1705 Fribourg Switzerland Tel: (41) 26-426-5555 Fax: (41) 26-426-5500 Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 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 Atmel Operations Memory 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 RF/Automotive Theresienstrasse 2 Postfach 3535 74025 Heilbronn, Germany Tel: (49) 71-31-67-0 Fax: (49) 71-31-67-2340 Microcontrollers 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 La Chantrerie BP 70602 44306 Nantes Cedex 3, France Tel: (33) 2-40-18-18-18 Fax: (33) 2-40-18-19-60 ASIC/ASSP/Smart Cards 1150 East Cheyenne Mtn. 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