View MICRF102YM_4766340.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

december 2006 1 micrf102 micrf102 micrel micrf102 qwikradio? uhf ask transmitter general description the micrf102 is a single chip transmitter ic for remote wireless applications. the device employs micrel?s latest qwi- kradio? technology. this device is a true ?data-in, antenna- out? monolithic device. all antenna tuning is accomplished automatically within the ic which eliminates manual tuning, and reduces production costs. the result is a highly reliable yet extremely low cost solution for high volume wireless applications. because the micrf102 is a true single-chip radio transmitter, it is easy to apply, minimizing design and production costs, and improving time to market. the micrf102 uses a novel architecture where the external loop antenna is tuned to the internal output stage. this trans- mitter is designed to comply with worldwide uhf unlicensed band intentional radiator regulations. the ic is compatible with virtually all ask/ook (amplitude shift keying/on-off keyed) uhf receiver types from wide-band super-regenerative radios to narrow-band, high performance super-heterodyne receiv- ers. the transmitter is designed to work with transmitter data rates from 100 to 20k bits per second. the automatic tuning, in conjunction with the external resistor, ensures that the transmitter output power stays constant for the life of the battery. when used with micrel?s family of qwikradio? receivers, the micrf102 provides the lowest cost and most reliable remote actuator and rf link system available. data sheets and support documentation can be found on micrel?s web site at: www.micrel.com. typical application pc vdd vss refosc ask micrf102 ask data input rp2 6.8k 0.1 f 4.7 f rp1 100k +5v +5v y1 antp antn stby 100k c3 12pf 50v (2.7pf 50v) c2 8.2pf 50v (4.7pf 50v) pcb antenna l1 features ? complete uhf transmitter on a monolithic chip ? frequency range 300mhz to 470mhz ? data rates to 20kbps ? automatic antenna alignment, no manual adjustment ? low external part count ? low standby current <0.04a applications ? remote keyless entry systems (rke) ? remote fan/light control ? garage door opener transmitters ? remote sensor data links ? tire pressure monitoring system (tpms) ? telemetry micrel, inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel + 1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.mic rel.com qwikradio is a trademark of micrel, inc. the qwikradio ics were developed under a partnership agreement with ait of orlando, fl orida qwikradio? ordering information part number temperature range package standard pb-free micrf102bm MICRF102YM -40c to +85c 8-pin soic
micrf102 micrel micrf102 2 december 2006 pin description pin number pin name pin function 1 pc power control input. the voltage at this pin should be set between 0.15v to 0.35v for normal operation. 2 vdd positive power supply input for the ic. this pin requires a large capacitor for ripple decoupling. a 4.7f is recommended. 3 vss this pin is the ground return for the ic. a power supply bypass capacitor connected from v dd to v ss should have the shortest possible path. 4 refosc this is the timing reference frequency which is the transmit frequency di- vided by 32. connect a crystal (mode dependent) between this pin and v ss , or drive the input with an ac-coupled 0.5v pp input clock. see ?reference oscillator? section in this data sheet. the crystal needs to have a 10pf load capacitance. 5 stby input for transmitter stand by control pin is pulled to v dd for transmit opera- tion and v ss for stand-by mode. the device requires 0.0 volts to be placed in stand by. 6 antn negative rf power output to drive the low side of the transmit loop antenna. the rf output stage is tuned in the data transitions in the ask pin. 7 antp positive rf power output to drive the high side of the transmit loop antenna. the rf output stage is tuned in the data transitions in the ask pin. 8 ask amplitude shift key modulation data input pin. for cw operation, connect this pin to v dd . several transitions of highs and lows are required to tune the output rf stages. pin con guration 1 pc vdd vss refosc 8 ask antp antn stby 7 6 5 2 3 4 8-pin soic (m)
december 2006 3 micrf102 micrf102 micrel electrical characteristics (note 4) speci cations apply for 4.75v < v dd < 5.5v, v pc = 0.35v, t a = 25c, freq refosc = 12.1875mhz, stby = v dd . bold values indicate -40c t a 85c unless otherwise noted. parameter condition min typ max units power supply standby supply current, i q v stby < 0.5v, v ask < 0.5v or v ask > v dd ? 0.5v 0.04 a mark supply current, i on @315mhz, note 5 6 10.5 ma @433mhz, note 5 8 12 ma space supply current, i off @315mhz 4 6 ma @433mhz 6 8.5 ma mean operating current 33% mark/space ratio at 315mhz, note 5 4.7 ma 33% mark/space ratio at 433mhz, note 5 6.7 ma rf output section and modulation limits: output power level, p out @315mhz; note 5, note 6 ?4 dbm @433mhz; note 5, note 6 ?4 dbm harmonics output, note 7 @315mhz 2nd harm. ?46 dbc 3rd harm. ?45 @433 mhz 2nd harm. ?50 dbc 3rd harm. ?41 extinction ratio for ask 40 52 dbc varactor tuning range note 8 3 5 7 pf reference oscillator section reference oscillator input 300 k impedance reference oscillator source 6 a current reference oscillator input 0.2 0.5 v pp voltage (peak-to-peak) note 1. exceeding the absolute maximum rating may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. devices are esd sensitive. handling precautions recommended. human body model, 1.5k in series with 100pf. note 4. speci cation for packaged product only. note 5. supply current and output power are a function of the voltage input on the pc (power control) pin. all speci cations in the ?electrical charac- teristics? table applies for condition v pc = 350mv. increasing the voltage on the pc pin will increase transmit power and also increase mark supply current. refer to the graphs ?output power versus pc pin voltage? and ?mark current versus pc pin voltage.? note 6. output power speci ed into a 50 equivalent load using the test circuit in figure 2. note 7. the micrf102 was tested to be compliant to part 15.231 for maximum allowable tx power. the transmitted power is measured 3 met ers from the antenna using transmitter board tx102-2a in figure 1. measurement results are summarized in table 1. note 8. the varactor capacitance tuning range indicates the allowable external antenna component variation to maintain tun-over-norma l production tolerances of external components. guaranteed by design, not tested in production. absolute maximum ratings (note 1) supply voltage(v dd ) ...................................................... +6v voltage on i/o pins ...............................v ss ?0.3 to v dd +0.3 storage temperature range ................... ?65c to + 150c lead temperature (soldering, 10 seconds) ............ + 300c esd rating ............................................................... note 3 operating ratings (note 2) supply voltage (v dd ) ......................................4.75v to 5.5v maximum supply ripple voltage ................................ 10mv pc input range .............................. 150mv < v pc < 350mv ambient operating temperature (t a ) .......... -40c to +85c programmable transmitter frequency range: ......................................................300mhz to 470mhz
micrf102 micrel micrf102 4 december 2006 parameter condition min typ max unit digital / control section calibration time note 9 , ask data rate 20kbps 25 ms power ampli er output hold off note 10 , stdby transition from low to high 6 ms time from stby crystal, esr < 20 transmitter stabilization time from external reference (500mvpp) 10 ms from stby crystal, esr < 20 19 ms maximum data rate ? ask modulation duty cycle of the modulating signal = 50% 20 kbits/s v stby enable voltage 0.75v dd 0.6v dd v stby sink current i stby = v dd 5 6.5 a ask pin v ih , input high voltage 0.8v dd v v il , input low voltage 0.2v dd v ask input current ask = 0v, 5.0v input current ?10 0.1 10 a note 9. when the device is rst powered up or it loses power momentarily, it goes into the calibration mode to tune up the transmit antenna. note 10. after the release of the stdby, the device requires an initialization time to settle the refosc and the internal pll. the rst mark state (ask high) after exit from stdby needs to be longer than the initialization time. after that, highs and lows in the ask pin cal librates the output rf stage. see figures 2, 3, and 4. pc vdd vss refosc ask micrf102 r2 6.8k c1 0.1f 16v +5vsw r1 100k antp antn stby +5vtx r3 100k r5 0 ? c3 12pf 50v (2.7pf 50v) c2 8.2pf 50v (4.7pf 50v) l1 pcbant c5 4.7f 6.3v c6 (np) 4.7f 6.3v y1 9.84375mhz (13.560mhz) c4 100pf 50v r4 (np) +5vsw +5vtx refosc data figure 1. frequency antenna height azimuth emi meter duty cycle corrected corrected 15:231b limit margin (mhz) polarity (meters) (0-360) reading correction reading reading (dbv/m) (db) (dbv/m) (db) (dbv/m) (v/m) 434.03 v 2.5 140 64.2 5.4 58.8 871.00 80.8 22 868.5 v 1 150 53.1 5.4 47.7 242.70 60.8 33.1 434.03 h 1 150 76.1 5.4 70.7 3427.80 80.8 10.1 868.5 h 1.5 295 60.1 5.4 54.7 543.30 60.8 26.1 1302 v 1 195 41.1 5.4 35.7 61.00 54 18.3 1736 v 1 280 51.3 5.4 45.9 197.20 60.8 14.9 1302 h 2.5 110 49.4 5.4 44 158.50 54 10 1736 h 1 113 44.5 5.4 39.2 91.20 60.8 21.6 note. higher order harmonics were found to be below the noise oor of the receiving system for testing. table 1. transmitted power measurement with transmitted frequency 433.92mhz, fcc limits and compliance
december 2006 5 micrf102 micrf102 micrel 0 5 10 15 20 25 0 100 200 300 400 500 600 current (ma) v pc (mv) mark current vs. pc pin voltage -35 -30 -25 -20 -15 -10 -5 0 5 0 100 200 300 400 500 600 output power (dbm) v pc (mv) output power vs. pc pin voltage typical characteristics rf output callibration time figure 2. rf out cal time example (45ms) ch 1 - ask pin, 1ms period ch 2 rf field figure 3. rf out cal time example from standby cycle (15ms) ch 1 - ask pin, 1ms period ch 2 rf field figure 4. rf out after shut down cycle example (11ms) ch 1 - ask pin, 1ms period ch 2 rf field, ch 4 - standby pin
micrf102 micrel micrf102 6 december 2006 functional description the block diagram illustrates the basic structure of the micrf102. identi ed in the gure are the principal functional blocks of the ic, namely the (1, 2, 3, 4, 5) uhf synthesizer, (6a/b) buffer, (7) antenna tuner, (8) power ampli er, (9) tx bias control, (10) reference bias and, (11) process tuner. the uhf synthesizer generates the carrier frequency with quadrature outputs. the in-phase signal (i) is used to drive the pa and the quadrature signal (q) is used to compare the antenna signal phase for antenna tuning purposes. the antenna tuner block senses the phase of the transmit signal at the antenna port and controls the varactor capacitor to tune the antenna. the power control unit senses the antenna signal and con- trols the pa bias current to regulate the antenna signal to the transmit power. block diagram tx bias control varactor device antenna tuning control power amp buffer vss antm antp ask buffer prescaler divide by 32 ref.osc pc vdd vdd (10) (5) (2) reference oscillator (1) vco (4) (3) (9) (8) (7) (11) (6a) (6b) stby reference bias phase detector the process tune circuit generates process independent bias currents for different blocks. a pcb antenna loop coupled with a resonator and a resistor divider network are all the components required to construct a complete uhf transmitter for remote actuation applications such as automotive keyless entry. included within the ic is a differential varactor that serves as the tuning element to insure that the transmit frequency and antenna are aligned with the receiver over all supply and temperature variations.
december 2006 7 micrf102 micrf102 micrel applications information design process the micrf102 transmitter design process is as follows: 1) set the transmit frequency by providing the cor- rect reference oscillator frequency. 2) ensure antenna resonance at the transmit fre- quency by: l ant = 0.2 length ln(length/d - 1.6) 10 -9 k where: length is the total antenna length in mm. d is the trace width in mm. k is a frequency correction factor. l ant is the approximate antenna inductance in henries. note 1. the total inductance, however, will be a little greater than the l ant calculated due to parasitics. a 2nh should be added to the calculated value. the l ant formula is an ap- proximated way to calculate the inductance of the antenna. the inductance value will vary however, depending on pcb material, thickness, ground plane, etc. the most precise way to measure is to use a rf network analyzer. 3) calculate the total capacitance using the follow- ing equation. c fl t ant = () 1 4 22 where: c t total capacitance in farads. = 3.1416. f = carrier frequency in hertz. l ant inductance of the antenna in henries. 4) calculate the parallel and series capacitors, which will resonate the antenna. 4.1) ideally for the micrf102 the series and paral- lel capacitors should have the same value or as close as possible. 4.2) start with a parallel capacitor value and plug in the following equation. c cc c s t var p = ? + () ? ? ? ? ? ? 1 11 where: c var is the center varactor capacitance (5pf for the micrf102) in farads. c p is the parallel capacitor in farads. c s is the series capacitor in farads. repeat this calculation until c s and c p are very close and they can be found as regular 5% commercial values. note 2. ideally, the antenna size should not be larger than the one shown in figure 7. the bigger the antenna area, the higher the loaded q in the antenna circuit will be. this will make it more dif cult to match the parallel and series capacitors. another point to take into consideration is the total ac rms current going through the internal varactor in the micrf102. this current should not exceed 16ma rms. the parallel capacitor will absorb part of this current if the antenna dimensions are appropriate and not exaggerated larger than the one shown here. note 3. a strong indication that the right capacitor values have been selected is the mean current with a 1khz signal in the ask pin. refer to the ?electrical characteristics? for the current values. note 4. for much smaller antennas, place a blocking capaci- tor for the series capacitance (around 100pf to 220pf) and use the following formula for the parallel capacitance c t = c p + c var . the blocking capacitor is needed to ensure that no dc current ows from one antenna pin to the other. 5) set pc pin to the desired transmit power. reference oscillator selection an external reference oscillator is required to set the transmit frequency. the transmit frequency will be 32 times the refer- ence oscillator frequency. ff tx refosc = 32 crystals or a signal generator can be used. correct reference oscillator selection is critical to ensure operation. crystals must be selected with an esr of 20 or less. if a signal generator is used, the input amplitude must be greater than 200 mv pp and less than 500 mv pp . antenna considerations the micrf102 is designed speci cally to drive a loop antenna. it has a differential output designed to drive an inductive load. the output stage of the micrf102 includes a varactor that is automatically tuned to the inductance of the antenna to ensure resonance at the transmit frequency. a high-q loop antenna should be accurately designed to set the center frequency of the resonant circuit at the desired transmit frequency. any deviation from the desired frequency will reduce the transmitted power. the loop itself is an induc- tive element. the inductance of a typical pcb-trace antenna is determined by the size of the loop, the width of the antenna traces, pcb thickness and location of the ground plane. the tolerance of the inductance is set by the manufacturing tolerances and will vary depending upon how the pcb is manufactured. the micrf102 features automatic tuning. the micrf102 automatically tunes itself to the antenna, eliminating the need for manual tuning in production. it also dynamically adapts to changes in impedance in operation and compensates for the hand-effect. automatic antenna tuning the output stage of the micrf102 consists of a variable capacitor (varactor) with a nominal value of 5.0pf tunable over a range of 3pf to 7pf. the micrf102 monitors the phase of the signal on the output of the power ampli er and automatically tunes the resonant circuit by setting the varactor value at the correct capacitance to achieve resonance. in the simplest implementation, the inductance of the loop antenna should be chosen such that the nominal value is
micrf102 micrel micrf102 8 december 2006 resonant at 5pf, the nominal mid-range value of the micrf102 output stage varactor. using the equation: l fc = 1 4 22 if the inductance of the antenna cannot be set at the nominal value determined by the above equation, a capacitor can be added in parallel or series with the antenna. in this case, the varactor internal to the micrf102 acts to trim the total capacitance value. l antenna c varactor c p c s figure 5. supply bypassing correct supply bypassing is essential. a 4.7f capacitor in parallel with a 100pf capacitor is recommended. the micrf102 is susceptible to supply-line ripple, if supply regulation is poor or bypassing is inadequate, spurs will be evident in the transmit spectrum. pc vdd vss refosc ask micrf102 l ask data input transformer output to 50? impedance transformation network off on rp2 (6.8k) rp1 (100k) +5v crystal z1 z3 z2 antp antm stby to 5 0 ? termination of spectrum analyzer figure 6. application test circuit for speci cation veri cation transmit power the transmit power speci ed in this datasheet is normalized to a load of 50ohm. the antenna ef ciency will determine the actual radiated power. good antenna design will yield transmit power in the range of 67db v/m to 80db v/m at 3 meters. the pc pin on the micrf102 is used to set the transmit power. the differential voltage on the output of the pa (power ampli er) is proportional to the voltage at the pc pin. with more than 0.35v on the pc pin the output ampli er becomes current limited. at this point, further increase in the pc pin voltage will not increase the rf output power in the antenna pins. low power consumption is achieved by decreasing the voltage in the pc pin, also reducing the rf output power and maximum range. output blanking when the device is rst powered up, or after a momentary loss of power, the output is automatically blanked (disabled). this feature ensures rf transmission only occurs under con- trolled conditions when the synthesizer is fully operational, plus preventing unintentional transmission at an undesired frequency. output blanking is key to guaranteeing compliance with uhf regulations by ensuring transmission only occurs in the intended frequency band.
december 2006 9 micrf102 micrf102 micrel design examples complete reference designs including gerber les can be downloaded from micrel?s website at: www.micrel.com/prod- uct-info/qwikradio.shtml. antenna characteristics in this design, the desired loop inductance value is determined according to the table below. freq. r xl ind q k (mhz) ( ? ) ( ? ) (nh) (xl/r) 300 1.7 84.5 44.8 39.72 0.83 315 2.34 89.3 45.1 39.65 0.85 390 3.2 161 47.4 52.00 0.90 434 2.1 136 50.0 78.33 0.96 the reference design, shown in figure 7, has an antenna meeting this requirement. figure 7. demo board pcb. loop antennas are often considered highly directional. in fact small loop antennas can achieve transmit patterns close in performance to a dipole antenna. the radiation pattern below is the theoretical radiation pattern for the antenna, as shown in figure 8. e-total, phi = 0? e-total, phi = 90? (180-phi) direction phi direction 30.0 180.0 60.0 120.0 150.0 150.0 120.0 60.0 30.0 0.0 figure 8. polar elevation pattern at 315mhz. the 0 degree plot is the radiation pattern in the plane of the transmitter pcb, the 90 degree plot represents the plane perpendicular to the pcb. micrel?s evaluation of the perfor- mance of the board in figure 8 indicates an even more uniform radiation pattern that the theoretical plot shown here. supply bypassing supply bypassing consists of three capacitors; c3 = 4.7f, c4 = 0.1fand c5 = 100pf c4 0.1 f 16v c5 100pf 50v c3 4.7 f 16v +5vtx vdd v ss micrf102 2 3 pc 1 ask 8 antp 7 antm 6 sb 5 refosc 4 figure 9. supply bypassing example to calculate c s and c p antenna inductance calculation length_mils = 2815 dmils = 70 k = 0.85 length length_mils 25.4 1000 length 71.501 = () = d dmils d = () = 25 4 1000 1 778 . . l 0.2 length ln length d 1.6 10 k l4410 9 9 = ? ? ? ? ? ? ? = ? ? where length and d are in mm and l is in h; where k is a constant dependent on pcb material, copper thickness, etc. micrf102 series capacitor calculation: f = 315 10 6 l = 46 10 -9 c var = 5 10 -12 c p = 12 10 -12 c fl c t t = = ? 1 4 2 587 10 22 12 . c cc c series tvar series = ? = ? 1 11 82 10 12 . micrf102 series capacitor calculation: f = 433.92 10 6 l = 52 10 -9 c var = 5 10 -12 c p = 2.7 10 -12 c fl c t t = = ? 1 4 2 587 10 22 12 .
micrf102 micrel micrf102 10 december 2006 c cc c c series t var p series = ? + = ? 1 11 39 10 12 . l1 = 52 10 -9 f1 = 433.92 10 6 c fl c t t 1 22 1 12 1 41 2 587 10 = = ? .
december 2006 11 micrf102 micrf102 micrel package information 8-pin soic (m)
micrf102 micrel micrf102 12 december 2006 micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 web http://www.micrel.com the information furnished by micrel in this datasheet is believed to be accurate and reliable. however, no responsibility is as sumed by micrel for its use. micrel reserves the right to change circuitry and speci cations at any time without noti cation to the customer. micrel products are not designed or authorized for use as components in life support appliances, devices or systems where malfu nction of a product can reasonably be expected to result in personal injury. life support devices or systems are devices or systems that (a) are intend ed for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a signi cant injury to the user. a purchaser?s use or sale of micrel products for use in life support appliances, devices or systems is at purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2006 micrel, incorporated.

▲Up To Search▲

Price & Availability of MICRF102YM

	To Download MICRF102YM Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .