Technical Description

FCC ID: BBQDTX1010-1

Operational Description

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FCCID_512007

Technical Description of the Circuit: The circuit is a RF thermometer transmitter part, the MCU TM8712 will measure the temperature and humidity and encode the data. Afterward, the data is transferred to the RF circuit, it is a fully integrated IC based OOK transmitter, the IC U2745B include a VCO, PLL and a power amplifier circuit. The IC U2745B will generate the frequency by the VCO and the PLL, the frequency is controlled by the reference crystal frequency, the reference frequency is 13.56MHz, then the PLL will multiple the frequency by 32 and it will generate the 433.92MHz. When the data from the MCU TM8712 transferred to the RF IC is high, it will turn on the power amplifier inside the IC U2745B and the IC U2745B will output the 433.92MHz. If the data transferred is low, it will turn off the power amplifier and the IC U2745B will not output the RF signal. Also there is a low pass filter at the output stage of the RF IC U2745B transmitter, it will suppress the harmonic and spurious emission.

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 ATARO90 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, UHF ASK ANT and LF Transmitter Electrostatic sensitive device. ‘ U2745B Observe precautions for handling. ‘:I\ 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 sys— tems. The main applications of the U2745B are in the areas of outside temperature metering, socket control, garage door opener, consumption metering, light/fan or air— condition control, jJalousies, wireless keyboard and various other consumer market applications. Rev. 4734A—~RKE—11/03 AlMeEL

Figure 1. System Block Diagram UHF ASK . UHF ASK Remote control transmitter Remote control receiver 1 Li cell U2745B U3745BM 8 i—Il ] Demad|————— | Control [— \1,3) 3§ ’LT § 3 o Keys Encoder ATARx9x a (FAImp a ‘ [ Z2 ax pu |— xto |— o %‘ | EJ l'_ LNA VCO I Figure 2. Block Diagram ASK )—lfl GND OR EN fiJ 1 PWARSET Power vccfi b S r PWRVCC vCO PA CLK P ANT | anp O ‘,—1 f PWRGND1 + 64 {— LEVCC 4? —L ; |— PWRGND2 " xT & n LrGnp O xTo1 LF (O— NC U2745B 4734A—RKE—11/03

U2745B Pin Configuration Figure 3. Pinning SSO16 s fo| oS E GND EN E ls] PWRSET vee [s 44] pwavee CLK E ]a ANT U2745B GND E E PWRGND1 LEVCC b fl PWRGND2 Lrenp [7 10| xtoi LF E J fj NC Pin Description Pin (_ Symbol Function 1 |___ ASK Modulation input ASK 2 ] EN Enable input 3 VCC Supply voltage 4 00000 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 Connection for crystal 11 PWRGND2 Power GND2 12 | PWRGND1 Power GND1 13 ANT RF output 14 PWRVCC Supply voltage power amplifier 15 PWRSET Applied to VCC o 0g6 0 —_GNp Ground 4734A—RKE—11/03 AlMEL

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 /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 pro— cessor does not need to poll a lock detect output. Functional Description ASK Transmission The U2745B is activated by EN = V5. V,g, must remain 0 V for 5 ms, then the output power can be modulated by means of pin ASK. Vey remains = Vg during the transmis— sion of the message. The ASK input activates the power amplifier and the PLL. Take—over of the Clock The clock of the crystal oscillator can be used for clocking the microcontrolier. The Pulse in the ATAROYO and ATAR890 have the special feature of starting with an integrated RC oscil— Microcontroller lator to switch on the U2745B with Vgy = V5. 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,, C;, and C, are block capacitors. The values of these capacitors depend on the board layout. C, = 1 nF, C3 = 1 nF, and C& = 22 nF are typically used here. For C;, the impedance between f= 100 MHz and f = 1 GHz should be as low as possible. Cloop1 and C1,,p2 are selected so that the antenna oscillates in resonance and the adap— tation to the appropriate impedance transformation is possible. Lreeg s an inductor for the antenna‘s DC current supply. A typical value is Lreeg = 220 NH. Legeg can be either printed on the PC board or be a discrete component. QOutput Power The following output network (see Figure 4 on page 5) can be used for output power Measurement evaluation, the exact values of L;, and C;, are dependent on the layout. L1p and C;, form the transformation network to adopt the output impedance of the 1C to 50 . The following table shows the values for an output power of 2 mW and an Table 1. Transformation Network t/MHz C10/pF L10/nH Zioad_opYQ 315 2.7 56 260 +330 | 433.92 1.8 33 185 + j268 4 Y2745B memmerarrrooronboon 4734A—RKE~11/03

U2745B Figure 4. Measurement Output Network VS PWRVCC L\O ANT ZLoad-opt C10 50 0 Figure 5. Application Circuit ASK ASK O_"——_—E OR Eg _ ENE 1 C Loop2 Powen I veo up ra CG _L 3 ck P CLK vco PA [A L Teeo O—— —[+] | |—"! 3.39 MHz GND PWRGND1 _ Cioopt L. 15| £ 12 I L2 T | L6 Ffl Lrvec * PWRGND2 ‘ c LTe / Lal L ———13.56 MHz S== LFGND | XTO 1 xtoi i— I [Z] 10]————1I:l|——| H— Es C, U2745B EN’C Ca ——— C, Antenna 4734A—RKE—11/03 AlMEL hnommmeommmmemmmmnemmmneti 5

Almet 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 Symbol! Min. Max. Unit [ Supply voltage Vs 6 V { Power dissipation Prot 250 mW ! Junction temperature T; 150 °C Storage temperature Tstg —55 125 °C Ambient temperature Tamb ~40 85 °C Thermal Resistance ( Parameters |___Symbol | Value Unit |_Junetion ambient |_ Bia ___| 180 KWw Electrical Characteristics All parameters are refered to GND (pin 5), Vsg = 3 V, Tapp = 25°C, unless otherwise specified The possible operating ranges refer to different circuit conditions: Vs = 2.2 V to 4.0 V at T;.,,, = ~40°C to +85°C Parameters Test Conditions | Symbol | Min. Typ. Max. Unit Supply current (power down) Vagk:s Vesy < 0.3 V, Vg < 8.6 V 1Soy 2 10 A Supply current (power up, output OFF)| Vas, = GND, Vey = V§, Vg = 8 V lSon 4.7 6.2 mA Supply current (power up, output ON) |Vagy = Vg, Vg = 3 V, Rpwaset = 12 KQ (Stransmit _ 10 12.5 mA Vg = 3 V, Tamp = 25°C, t = 433.92 MHz Output power Rewaser = 1.2 kQ P Bef 1 3 5 dBm Output power variation for f = 315 MHz compared to f= 315 MHz BPBef 1.5 dB f = 433.92 MHz Pout = Pret + APrer at Poy, = 2.0 mW, the load impedance must be selected Maximum peak output to meet the V,,, maximum v V —0.7 V v antenna voltage requirement, the supply current is not outmax § Y (peak} dependent on the load impedance tolerance o {, +(x fag) Where fog = 6.78 MHz Spurious emission Load capacitance at CLK < 3 pF P t = 230 MHz to 470 MHz Em 40 dBC f < 230 MHz, f > 470 MHz Em —58 dBC . 13.56 — 13.56 + Oscillator frequency XTO Crystal frequency = 13.56 MHz frro 30 ppm 13.56 30 ppm MHz For best LO noise Loop bandwidth Loop filter components: Bloop 100 kHz |C» = 8.9 nF, C, = 15 nF, R, = 220 Q . Referring to the phase comparator _ _ Phase noise PLL foc = 6.78 MHz PNpy_ 111 105 dBC/Hz . at 1 MHz PNvco —90 Phase noise VCO at 36 MHz PNvCo 192 dBC/Hz 4734A—RKE—11/03

ooo U2745B Electrical Characteristics (Continued) All parameters are refered to GND (pin 5), Vs = 3 V, Tayp = 25°C, unless otherwise specified The possible operating ranges refer to different circuit conditions: V; = 2.2 V to 4.0 V at T;,,, = —40°C to +85°C Parameters \Test Conditions Symboi Min. Typ. | Max. Unit Frequency range of the VCO fuco 310 440 MHz Clock output (CMOS microcontroller compatible) ClKou fou!128 MHz Load capacitance at CLK Cork 10 pF . fxro = 13.56 MHz Rs 80 Series resonance R of the crystal fkro = 9.84 MHz Rs 100 Q ASK modulation frequency rate Duty cycle of the f 0 20 kHz modulation signal = 50% modASK [GUK output i — Output current Low Voy = 0.2 x Vg loy 150 LA — Output current Low Vorx = 0.3 x Vs loy 200 LA — Output current High Vouy = 0.8 x V3 lon ~150 LA — Output current High Vorg = 0.7 * Vg loh ~200 100 yA ASK input — Low level input voltage Vase 0.3 V — High level input voltage Vaskn 1.7 V — Input current High laskn 140 pA Enable ASK Ven — Low level input voltage Veski 0.3 V — High level input voltage Vrekn 1.7 V — Input current High legkn 140 yA 4734A—RKE—11/03 AlMeL bommommemmmmemmemmememee i 7

Almet in Ordering Information Extended Type Number U Package Remarks U2745B—MFB SSO16 Tube U2745B—MFBG3 SSO16 Taped and reeled Package Information Smax. 4.9+0.1 1.7max. 0.6 1.4 T0 0.25 0.635 nom . 3.95 max. 71x0.635=4.445 nom. <—€ technical drawings according to DN specifications Orawing refers to following types: SSO16 Package acc. JEDEC MO 137 AB U2745B ocm 4734A—RKE—11/03

AlMEL m> Atmel Corporation Atmel Operations 2325 Orchard Parkway Memory RF/Automotive San Jose, CA 95131, USA 2325 Orchard Parkway Theresienstrasse 2 Tel: 1(408) 441—0311 San Jose, CA 95131, USA Postfach 3535 Fax: 1(408) 487—2600 Tel: 1(408) 441—0311 74025 Heilbronn, Germany Fax: 1(408) 436—4314 Tel: (49) 71—31—67—0 Fax: (49) 71—31—67—2340 Regional Headquarters Microcontrollers Europe 2325 Orchard Parkway 1150 East Cheyenne Mitn. Blvd. Atmel Sarl San Jose, CA 95131, USA Colorado Springs, CO 80906, USA Route des Arsenaux 41 Tel: 1(408) 441—0311 Tel: 1(719) 576—3300 Case Postale 80 Fax: 1(408) 436—4314 Fax: 1(719) 540—1759 CH—1705 Fribourg Switzerland La Chantrerie Biometrics/Imaging/Hi—Rel MPU/ Tel: (41) 26—426—5555 BP 70602 High Speed Converters/RF Datacom Fax: (41) 26—426—5500 44306 Nantes Cedex 3, France Avenue de Rochepleine Tel: (33) 2—40—18—18—18 BP 123 Asia Fax: (33) 2—40—18—19—60 38521 Saint—Egreve Cedex, France Room 1219 Tel: (33) 4—76—58—30—00 Chinachem Golden Plaza ASIC/ASSP/!Smart Cards Fax: (33) 4—76—58—34—80 77 Mody Road Tsimshatsui Zone Industrielle East Kowloon 13106 Rousset Cedex, France Hong Kong Tel: (33) 4—42—53—60—00 Tel: (852) 2721—9778 Fax: (33) 4—42—53—60—01 Fax: (852) 2722—1369 1150 East Cheyenne Mtn. Bivd. Japan Colorado Springs, CO 80906, USA 9F, Tonetsu Shinkawa Blag. Tel: 1(719) 576—3300 1—24—8 Shinkawa Fax: 1(719) 540—1759 Chuo—ku, Tokyo 104—0033 Japan Scottish Enterprise Technology Park Tel: (81) 3—3523—3551 Maxwell Building Fax: (81) 3—3523—7581 East Kilbride G75 OQR, Scotland Tel: (44) 1355—803—000 Fax: (44) 1355—242—743 Literature Requests www.atmel.com/literature Disclaimer: Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company‘s standard warranty which is detailed in Atmel‘s Terms and Conditions located on the Company‘s web site. The Company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel‘s products are not authorized for use as critical components in life support devices or systems. © Atmel Corporation 2003. All rights reserved. Atmel® and combinations thereof are the registered trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be the trademarks of others. /"”J Printed on recycled paper. 4734A—RKE—11/03


Document Created: 2005-01-20 10:32:05
Document Modified: 2005-01-20 10:32:05
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