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rct-433-asbr datasheet revision 1.4.0
rct-433-asbr datasheet 1 radiotronix, inc. rct-433-asbr datasheet ? radiotronix 905 messenger lane moore, oklahoma 73160 phone 405.794.7730 ? fax 405.794.7477 www.radiotronix.com
rct-433-asbr datasheet 2 document control signed date created by sjm 5/21/2002 engineering review trm 8/21/2003 marketing review tje 6/13/2007 approved- eng. trm 8/21/2003 approved- mar. tje 6/13/2007 revised history revision signed date description 1.0.0 sjm 5/21/2002 document created 1.2.0 bfa 7/30/2003 revision 1.3.0 sjm 8/21/2003 added troubleshooting and design tips 1.4.0 gwh 6/7/2005 added rct-433-asb specification to datasheet.
rct-433-asbr datasheet 3 table of contents 1. description .................................................................................................................... ......................... 5 1.1. f eatures ............................................................................................................................... ................. 5 1.2. a pplications ............................................................................................................................... ............ 5 2. theory of operation ............................................................................................................ .............. 6 2.1. ook m odulation ............................................................................................................................... .... 6 2.1.1. saw stabilized oscillator ...................................................................................................... ........... 6 2.1.2. data rate ...................................................................................................................... .................... 7 2.1.3. power s upply ................................................................................................................... ................. 7 2.1.4. antenna ou tput ................................................................................................................. ................ 7 3. pin out di agram ................................................................................................................ ..................... 9 3.1. p in d escription ............................................................................................................................... ....... 9 3.2. m echanical d rawings ........................................................................................................................... 9 4. reflow pr ofile................................................................................................................. ................... 10 5. electrical spec ificat ions...................................................................................................... ........ 11 5.1. a bsolute m aximum r atings ................................................................................................................. 11 5.2. d etailed e lectrical s pecifications ................................................................................................... 11 6. custom appl icatio ns ............................................................................................................ ............ 12 7. ordering in formation ........................................................................................................... ........... 13 7.1. c ontact i nformation .......................................................................................................................... 13 7.1.1. technical support .............................................................................................................. ............. 13 7.1.2. sales support.................................................................................................................. ................ 13
rct-433-asbr datasheet 4 index of tables table 1, pin descriptions ...................................................................................................... ................................ 9 table 2, suggeste d reflow profile .............................................................................................. ........................ 10 table 3, absolute maximum ratings.............................................................................................. ..................... 11 table 4, detailed electr ical specifications .................................................................................... ...................... 11 table of figures figure 1: t-p ad exam ple ........................................................................................................ ............................... 8 figure 2: mechanical dr awing for rc t-433-asbr.................................................................................. ............. 9 figure 3: suggeste d pad layout................................................................................................. .......................... 9
rct-433-asbr datasheet 5 1. description the rct-433-asbr is ideal for remote control applications where low cost and longer range is required. the transmitter operates from a 1.5-12v supply, making it ideal for battery-powered applications. the transmitter employs a saw-stabilized oscillator, ensuring accurate fr equency control for best range performance. output power and harmonic emissions are easy to control, making fcc and etsi compliance easy. the manufacturing-friendly smt style package and low-cost make the rct-433-asbr suitable for high volume applications. the rct-433-asbr is suitable for ir re flow ovens and hot air soldering. important: rct-433-asbr is rohs compliant! 1.1. features ? 315 / 418/ 433.92 mhz versions ? low cost ? 1.5 ? 12 v operation ? 5 ma current consumption at 3 v ? small size ? 0 dbm output power at 3 v ? 4800 baud operation 1.2. applications ? remote keyless entry (rke) ? remote lighting controls ? on-site paging ? asset tracking ? wireless alarm and security systems ? long range rfid ? automated resource management chapter 1
rct-433-asbr datasheet 6 2. theory of operation 2.1. ook modulation ook modulation is a binary form of amplitude modulation. when a logical 0 (data line low) is being sent, the transmitter is off, fully suppressing the carrier. in this state, the transmi tter current is very low, less than 1ma. when a logical 1 is being sent, the carrier is fully on. in this state, the module current consumption is at its highest, about 4.5ma with a 3v power supply. ook is the modulation method of choice for remote cont rol applications where power consumption and cost are the primary factors. because ook trans mitters draw no power when they transmit a 0, they exhibit significantly better power consumption than fsk transmitters. ook data rate is limited by the start-up time of the oscilla tor. high-q oscillators whic h have very stable center frequencies take longer to start-up than low-q oscillator s. the start-up time of th e oscillator determines the maximum data rate that the transmitter can send. design hint (using the rct-433-asbr wi th a microcontroller uart ) : data should be inverted when using the transmitter with a uart. the normal marking stat e of a uart is a logic 1, which will cause constant transmission. by inverting the data, the transmitter will be off in a marking state and on in a spacing state (logical 0), ensuring that the transmitter is on only when data is be ing sent. the output of the receiver would also need to be inverted to properly recover data. 2.1.1. saw stabilized oscillator the transmitter is basically a negative resistance lc oscillator whose center frequency is tightly controlled by a saw resonator. saw (surface ac oustic wave) resonators are fundamental frequency devices that resonate at frequencies much higher th an crystals. the output of the oscillator is derived directly from the collector of the oscillator transistor. it is, therefore, very sensitive to vswr. the module is designed to work with a 50 ohm load, which exhibits a vswr of 1. the designer must ensure that the antenna exhibits no more than a vswr of 2 to guarantee operation. this is particularly true for pcb trace antennas. if t he module does not appear to have any output at the antenna port, it is likely that the antenna does not meet this requirement. troubleshooting hint: if the module appears to have no output at the antenna port, try the following: disconnect the antenna and put a 1000pf cap in series with a 51 ohm resistor to ground. this will ensure that the transmitter is properly loaded. then look at the output with a scope and you should see the oscillator working. if it is working, the antenna is not properly tuned and that is the reason that the module is not working properly. if not, then check the power supply and data input for proper voltage levels. chapter 2
rct-433-asbr datasheet 7 2.1.2. data rate the oscillator start-up time is on the order of 40usec, which limits the maximum data rate to 4.8 kbit/sec. troubleshooting hint: if the module appears to have a good output, but your data rate is corrupted, that could be a sign that the start-up time of the o scillator is too long. the load on the antenna affects oscillator start-up time. to determine the start-up time of the oscillator, use a 2 channel digital storage oscilloscope. attach channel 1 to the data input and channel 2 to the antenna output (don?t worry; it won?t affect the antenna vswr). trigger the scop e on a rising edge on channel 1. now, toggle the data pin from low to high and capture the resulting waveform. you should see a square edge on channel 1 and the oscillator ring-up on channel 2. measure the time between the rising edge on channel 1 and when the oscillator waveform is at its full voltage swing, and you have the start-up time. to determine if the antenna is the problem, remove it and place a 1000pf cap in series with a 51-ohm resistor to ground and repeat the test. if the start-up time is correct with the test load, the problem is the antenna. 2.1.3. power supply the rct-433-asbr is designed to oper ate from a 1.5 -12v power supply. it is crucial that this power supply be very quiet. the power supply should be bypassed using a 0.01uf low-esr ceramic capacitor and a 4.7uf ceramic capacitor. these c apacitors should be placed as close to the power pins as possible. 2.1.4. antenna output pin 1 is a 50 ohm antenna output. it will support most antenna types, including printed antennas integrated directly onto the pcb. the performance of the different antennas varies. there are many good application notes available that describe external and pcb trace antennas. we maintain a list in the technical support section of our website. design hint (antenna traces): any time a trace is longer than 1/8 th the wavelength of the frequency it is carrying, it should be a 50 ohm micro strip. this ensures that a proper match is maintained between the transmitter output and the antenna. design hint (harmonic filters): the impedance at the antenna power affects the vswr, power output, and harmonic output of the transmitter. in most cases, the output of the transmitter may need a low-pass lc filter to reduce harmonic emissions. a good calculator is available on line at http://www- users.cs.york.ac.uk/~fisher/lcfilter/ . calculate the filter for a 3db cut-off of the module?s center frequency plus 10%. for example, the cut-off for a 433.92 mhz module would be about 470 mhz.
rct-433-asbr datasheet 8 design hint (t-pad): the rct-433-asbr transmitter can be sensitive to unbalanced or unmatched loads and could fail to operate or operate intermitt ently in this condition. try to match your antenna load as close to 50 ohms as possible. use a t-pad if necessary to give the transmitter a close 50 ohm match before your antenna. a t-pad will also act as an attenuator. see figure 6 below, for a t-pad match/attenuator circuit. figure 1: t-pad example resistor values in this t-pad example are: r1 ? 10 ohms r3 ? 150 ohms
rct-433-asbr datasheet 9 3. pin out diagram 3.1. pin description pin no. pin name description 1 ant 50 ohm antenna output. the antenna port impedance affects output power and harmonic emissions. an l-c low-pass filter may be needed to sufficiently filter harmonic emissions. 2 gnd transmitter ground. connect to ground plane. 3 data digital data input. this input is cmos compatible and should be driven with cmos level inputs. 4 vcc pin 4 provides operating voltage for the transmitter. vcc should be bypassed with a .01uf ceramic capacitor and filter ed with a 4.7uf tantalum capacitor. noise on the power supply will degrade transmitter noise performance. table 1, pin descriptions 3.2. mechanical drawings figure 2: mechanical drawing for rct-433-asbr figure 3: suggested pad layout chapter 3
rct-433-asbr datasheet 10 4. reflow profile the rct-433-asbr is su itable for reflow ovens a nd heat guns. to prevent da mage to the module through excess heat, the reflow oven temperature profiling is ve ry important. a suggested oven profile is detailed in table 2 below. steps are: first, preheating shall be fixed at 140 ? 160 degrees celsius for 60 - 90 seconds. then ascending time to preheating temperature 150 degrees celsius shall be 30 seconds minimum. last, heating shall be fixed at 200 degrees celsius for 50 ? 60 seconds and at 230 +/-10 degrees celsius. table 2, suggested reflow profile important: the modules should be assembled with a "no clean" solder process only. washing may cause moisture to become trapped under t he ceramic cap. do not po wer the module while wet, it will cause damage. chapter 4
rct-433-asbr datasheet 11 5. electrical specifications 5.1. absolute maximum ratings parameter min max units power suppy and all input pins -0.3 +15 vdc storage temperature -50 100 o c soldering temperature (10sec.) 1 n/a 350 o c table 3, absolute maximum ratings note: the rct-433-asbr is suitable for ir reflow and hot air soldering. 5.2. detailed electrical specifications parameter (general) symbol min typ max units notes operating voltage v cc 1.5 3.0 12 volts dc operating current data = vcc i cc 4.5 ma @ 3v operating current data = gnd i cc 100 ua @ 3v frequency accuracy tol fc -75 0 +75 khz @ 3v f c 315 mhz rct-315-asbr f c 418 mhz rct-418-asbr center frequency f c 433 mhz rct-433-asbr output power 0 dbm @ 3v baud rate - nrz dc 4800 bps table 4, detailed electrical specifications chapter 5
rct-433-asbr datasheet 12 6. custom applications for cost-sensitive applications, such as wireless se nsors and amr, radiotronix can embed the application software directly into the microcontroll er built into the module. for more information on this service, please contact radiotronix. chapter 6
rct-433-asbr datasheet 13 7. ordering information product part number description rct-315-asbr ook rf transmitter (315 mhz) rct-418-asbr ook rf transmitter (418 mhz) rct-433-asbr ook rf transmitter (433 mhz) 7.1. contact information corporate headquarters: 905 messenger lane moore, oklahoma 73160 405-794-7730 website: www.radiotronix.com support: support@radiotronix.com 7.1.1. technical support radiotronix has built a solid technical support infrastructure so that you can get answers to your questions when you need them. our primary technical support tools are the support forum and knowledge base found on our website. we are continuously updating these to ols. to find the latest information about these technical support tools, please visit http://www.radiotronix.com/support . our technical support engineers are available mon-fri between 9:00 am and 5:00 pm central standard time. the best way to reach a technical support engineer is to submit a webcase. webcase submissions can be made at http://www.radiotronix.com/support/webcase.asp . for customers that would prefer to talk directly to a support engineer, we do offer phone support free of charge. 7.1.2. sales support our sales department can be reached via e-mail at sales@radiotronix.com or by phone at 405-794- 7730. our sales department is available mon-fri bet ween 8:30 am and 5:00 pm central standard time. visit our web site at http://www.radiotronix.com/corpsales.asp for information on where to buy our products. chapter 7

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