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 2.2v to 4.0v in th e temperature range of ?40c to 85c xto output for clocking the microcontroller, thereby, together with the atar090 or atar890, resulting in the optimum system cost-effectiveness one-chip solution with mi nimum external circuitry single-ended open-collector output (same antennas can be used as in discrete solutions, simpler matching of magnetic loop antennas) esd protection according to mil-std 883 (4 kv hbm) except pins xto1, xto2, ant and lf very small sso16 package, pitch 0.635, 150 mil 1. description the ATA2745 is a pll transmitter ic which has been developed especially for the demands of rf low-cost data transmission systems at data rates up to 20 kbaud. the transmitting freq uency range is 31 0 mhz to 440 mhz. it can be used in ask sys- tems. the main applications of the ATA2745 are in the areas of outside temperature metering, socket control, garage door openers, consumption metering, light/fan or air- conditioning controls, jalous ies, wireless keyboards, and various other consumer market applications. uhf ask transmitter ATA2745 4898b?rke?08/06
2 4898b?rke?08/06 ATA2745 figure 1-1. system block diagram figure 1-2. block diagram demod. if amp lna vco pll xto control ata3745 1...3 micro- controller power amp. xto vco pll ATA2745 antenna antenna uhf ask remote control transmitter uhf ask remote control receiver encoder atarx9x 1 li cell keys 64 f pa n f or power up vco xto ask en vcc clk gnd lfvcc lfgnd lf gnd pwrset pwrvcc ant pwrgnd1 pwrgnd2 xto1 nc ATA2745
3 4898b?rke?08/06 ATA2745 2. pin configuration figure 2-1. pinning sso16 vcc clk gnd lfvcc lfgnd lf ask en 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 pwrvcc ant pwrgnd1 pwrgnd2 xto1 nc gnd pwrset ATA2745 table 2-1. pin description pin symbol function 1 ask modulation input ask 2 en enable input 3 vcc supply voltage 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 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 16 gnd ground
4 4898b?rke?08/06 ATA2745 3. 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 consid- erably 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 fre- quencies, crystals have a very fast start-up time (< 1.5 ms), whereby a wait time of 5 ms 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. 4. functional description 4.1 ask transmission the ATA2745 is activated by en = v s . v ask must remain 0v for 5 ms, then the output power can be modulated by means of pin ask. v en remains equal to v s during the transmission of the message. the ask input activates the power amplif ier and the pll. 4.2 take-over of the clock pu lse 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 ATA2745 with v en = v s . 5 ms later, the 3.39-mhz clock frequency is present, so that the message can be sent with crystal accuracy. 5. application circuit the following component values are reco mmendations for a typical application. c 4 , c 5 , and c 6 are block capacitors. the values of these capacitors depend on the board layout. c 4 =1nf, c 5 = 1 nf, and c 6 = 22 nf are typically used here. for c 5 , the impedance between f = 100 mhz and f = 1 ghz should be as low as possible. c loop1 and c loop2 are selected so that the antenna oscillates in resonance and the matching to the appropriate impedance transformation is possible. l feed is an inductor for the antenna's dc current supply. a typical value is l feed =220nh. l feed can be either printed on the pc board or be a discrete component.
5 4898b?rke?08/06 ATA2745 5.1 output power measurement the following output network ( figure 5-1 on page 5 ) can be used for output power evaluation, the exact values of l 10 and c 10 are dependent on the layout. l 10 and c 10 form the transformation network to adopt the output impedance of the ic to 50 ? . the following table shows the values for an output power of 2 mw and an r pwrset =1.2k ? . figure 5-1. measurement output network figure 5-2. application circuit table 5-1. transformation network f [mhz] c10 [pf] l10 [nh] z load-opt [ ? ] 315 2.7 56 260 + j330 433.92 1.8 33 185 + j268 pwrvcc ant v s l 10 c 10 50 ? z load-op t 16 1 2 3 4 5 6 7 8 15 14 13 12 11 10 9 64 f pa n f or power up vco xto ask en vcc clk gnd lfvcc lfgnd lf gnd pwrset pwrvcc ant pwrgnd1 pwrgnd2 xto1 nc c 4 r pwrset l feed c loop1 13.56 mhz c 3 +v s = 2.2 ... 4.0 v c loop2 c 6 c 1 c 2 r 4 ask en clk 3.39 mhz c 5 ATA2745 antenna
6 4898b?rke?08/06 ATA2745 electrostatic sensitive device. observe precautions for handling. 6. 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 t hose indicated in the operational sections of this specification is not implied. exposure to absolute maximum rati ng conditions for extended periods may affect device reliability . parameters symbol min. max. unit supply voltage v s 6v power dissipation p tot 250 mw junction temperature t j 150 c storage temperature t stg ?55 125 c ambient temperature t amb ?40 85 c 7. thermal resistance parameters symbol value unit junction ambient r thja 180 k/w 8. electrical characteristics all parameters are refered to gnd (pin 5), v s = 3v, t amb = 25c, unless otherwise specified the possible operating ranges refer to different circuit conditions: v s = 2.2v to 4.0v at t amb = ?40c to +85c parameters test conditions symbol min. typ. max. unit supply current (power down) v ask , v fsk 0.3v, v s < 3.6v is off 210a supply current (power up, output off) v ask = gnd, v en = v s , v s = 3v is on 4.7 6.2 ma supply current (power up, output on) v ask = v s , v s = 3v, r pwrset = 1.2 k ? is transmit 10 12.5 ma output power v s = 3v, t amb = 25 c, f = 433.92 mhz r pwrset = 1.2 k ? p ref 135dbm output power variation for f = 315 mhz compared to f = 433.92 mhz f = 315 mhz p out = p ref + ? p ref ? p ref 1.5 db maximum peak output antenna voltage at p out = 2.0 mw, the load impedance must be selected to meet the v out maximum requirement, the supply current is not dependent on the load impedance tolerance v outmax v s ? 0.7v v (peak) spurious emission f o (n f pc ) where f pc = 6.78 mhz load capacitance at clk 3pf f = 230 mhz to 470 mhz f < 230 mhz, f > 470 mhz em em ?40 ?58 dbc dbc oscillator frequency xto crystal frequency = 13.56 mhz f xto 13.56 ? 30 ppm 13.56 13.56 + 30 ppm mhz
7 4898b?rke?08/06 ATA2745 loop bandwidth for best lo noise loop filter components: c 2 = 3.9 nf, c 1 = 15 nf, r 4 = 220 ? b loop 100 khz phase noise pll referring to the phase comparator f pc = 6.78 mhz pn pll ?111 ?105 dbc/hz phase noise vco at 1 mhz at 36 mhz pn vco pn vco ?90 ?122 dbc/hz frequency range of the vco f vco 310 440 mhz clock output (cmos microcontroller compatible) clk out f out /128 mhz load capacitance at clk c clk 10 pf series resonance r of the crystal f xto = 13.56 mhz f xto = 9.84 mhz rs rs 80 100 ? ask modulation frequency rate duty cycle of the modulation signal = 50% f modask 020khz clk output - output current low - output current low - output current high - output current high v clk = 0.2 v s v clk = 0.3 v s v clk = 0.8 v s v clk = 0.7 v s i ol i ol i oh i oh 150 200 ?150 ?200 100 a a a a ask input - low level input voltage - high level input voltage - input current high v askl v askh i askh 1.7 0.3 140 v v a enable ask - low level input voltage - high level input voltage - input current high v en v fskl v fskh i fskh 1.7 0.3 140 v v a 8. electrical characteristics (continued) all parameters are refered to gnd (pin 5), v s = 3v, t amb = 25c, unless otherwise specified the possible operating ranges refer to different circuit conditions: v s = 2.2v to 4.0v at t amb = ?40c to +85c parameters test conditions symbol min. typ. max. unit
8 4898b?rke?08/06 ATA2745 10. package information 9. ordering information extended type number package remarks ATA2745m-tcqy sso16 taped and reeled, pb-free
9 4898b?rke?08/06 ATA2745 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 4898b-rke-08/06 ? put datasheet in a new template ? section 9 ?ordering information? on page 8 changed
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