View MICRF002YM-FS12_1813449.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

micrf002/rf022 300-440mhz qwikradio ? ask receiver qwikradio is a registered trademark of micr el, inc. the qwikradio ics were developed under a partnership agreement with ait of orlando, fl. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 ( 408 ) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com july 2008 m9999-070808 general description the micrf002 is a single chip ask/ook (on-off keyed) rf receiver ic. this device is a true ?antenna-in to data-out? monolithic device. all rf and if tuning is accomplished automatically within the ic which eliminates manual tuning and reduces produ ction costs. the result is a highly reliable yet low cost solution. the micrf002 is a fully featur ed part in 16-pin packaging, the micrf022 is the same part packaged in 8-pin packaging with a reduced feature set (see ?ordering information? for more information). the micrf002 is an enhanced version of the micrf001 and micrf011. the micrf002 provides two additional functions over the micrf001/0 11, (1) a shutdown pin, which may be used to turn the device off for duty-cycled operation, and (2) a ?wake-up ? output, which provides an output flag indicating when an rf signal is present. these features make the micrf002 ideal for low and ultra-low power applications, such as rke and remote controls. all if filtering and post- detection (demodulator) data filtering is provided within the micrf002, so no external filters are necessary. one of four demodulator filter bandwidths may be selected externally by the user. the micrf002 offer two modes of operation; fixed-mode (fix) and sweep-mode (swp). in fixed-mode the micrf002 functions as a conven tional superhet receiver. in sweep-mode the micrf0 02 employs a patented sweeping function to sweep a wider rf spectrum. fixed- mode provides better selectivity and sensitivity performance and sweep-mode enables the micrf002 to be used with low cost, imprecise transmitters. data sheets and support doc umentation can be found on micrel?s web site at: www.micrel.com. qwikradio ? features ? 300mhz to 440mhz frequency range ? data-rate up to 10kbps (fixed-mode) ? low power consumption ? 2.2ma fully operational (315mhz) ? 0.9a in shutdown ? 220a in polled operation (10:1 duty-cycle) ? wake-up output flag to enable decoders and microprocessors ? very low rf re-radiation at the antenna ? highly integrated with extremely low external part count applications ? automotive remote keyless entry (rke) ? remote controls ? remote fan and light control ? garage door and gate openers _________________________________________________________________________________________________________ ordering information part number demodulator bandwidth operating mode shutdown wakeb output flag package lead finish micrf002ym user programmable fixed or sweep yes yes 16-pin soic pb-free micrf022ym-sw48 5000hz sweep no yes 8-pin soic pb-free micrf022ym-fs12 1250hz fixed yes no 8-pin soic pb-free micrf022ym-fs24 2500hz fixed yes no 8-pin soic pb-free micrf022ym-fs48 5000hz fixed yes no 8-pin soic pb-free
micrel, inc. micrf002/rf022 july 2008 2 m9999-070808 typical application sel0 sel0 swen vssrf refosc vssrf sel1 ant cagc vddrf wakeb vddbb shut cth do nc vssbb 0.047f 4.8970mhz data output micrf002 4.7f +5v 15nh 10pf 68nh 1/4 wave monopole 315mhz 800bps on-off keyed receiver pin configuration 1 sel0 vssrf vssrf ant vddrf vddbb cth nc 16 swen refosc sel1 cagc wakeb shut do vssbb 15 14 13 12 11 10 9 2 3 4 5 6 7 8 1 vssrf ant vddrf cth 8 refosc cagc shut/wakeb do 7 6 5 2 3 4 16-pin soic (m) 8-pin soic (m) 8-pin options the standard 16-pin package allows complete control of all configurable features. some reduced function 8-pin versions are also available, see ?ordering information? on page 1. for high-volume applications additional customized 8-pin devices can be produced. swen, sel0 and sel1 pins are internally bonded to reduce the pin count; pin 6 may be configured as either shut or wakeb demodulator bandwidth sel0 sel1 sweep-mode fixed-mode 1 1 5000hz 10000hz 0 1 2500hz 5000hz 1 0 1250hz 2500hz 0 0 625hz 1250hz table 1. nominal demodulator filter bandwidth vs. sel0, sel1 and operating mode
micrel, inc. micrf002/rf022 july 2008 3 m9999-070808 pin description pin number soic-16 pin number soic-8 pin name pin name 1 ? sel0 bandwidth selection bit 0 (digital input): used in conjunction with sel1 to set the desired demodulator filter bandwidth. see table 1. internally pulled-up to vddrf. 2, 3 1 vssrf rf power supply: ground return to the rf section power supply. 4 2 ant antenna (analog input): for optim al performance the ant pin should be impedance matched to the antenna. see ?applications information? for information on input impedance and matching techniques. 5 3 vddrf rf power supply: positive s upply input for the rf section of the ic. 6 ? vddbb base-band power supply: positive supply input for the baseband section (digital section) of the ic. 7 4 cth data slicing threshold capacitor (analog i/o): capacitor connected to this pin extracts the dc average value fr om the demodulated waveform which becomes the reference for the int ernal data slicing comparator. 8 ? nc not internally connected 9 ? vssbb base-band power supply: ground return to the baseband section power supply. 10 5 do data output (digital output) 11 6 shut shutdown (digital input): shutdown-mod e logic-level control input. pull low to enable the receiver. internally pulled-up to vddrf. 12 ? wakeb wakeup (digital output): active-low out put that indicates detection of an incoming rf signal. 13 7 cagc automatic gain control (analog i/o): connect an external capacitor to set the attack/decay rate of the on-ch ip automatic gain control. 14 ? sel1 bandwidth selection bit 1 (digital input): used in conjunction with sel0 to set the desired demodulator filter bandwidth. see table 1. internally pulled-up to vddrf. 15 8 refosc reference oscillator: timing re ference, sets the rf receive frequency. 16 ? swen sweep-mode enable (digital input): sw eep- or fixed-mode operation control input. swen high= sweep mode; swen low = conventional superheterodyne receiver. internally pulled-up to vddrf.
micrel, inc. micrf002/rf022 july 2008 4 m9999-070808 absolute maximum ratings (1) supply voltage (v ddrf , v ddbb )........................................+7v input/output voltage (v i/o ). ....................v ss ?0.3 to v dd +0.3 junction temperature (t j ) ....................................... +150c storage temperature (t s ) ........................... ?65c to 150c lead temperature (solde ring, 10 se c.)...................... 260c esd rating (3) operating ratings (2) supply voltage (v ddrf , v ddbb ).................... +4.75v to +5.5v rf frequency range .............................. 300mhz to 440hz data duty-cycle ................................................20% to 80% reference oscillator input range.............. 0.1v pp to 1.5v pp ambient temperature (t a ) .......................... ?40c to +85c electrical characteristics (4) v ddrf = v ddbb = v dd where +4.75v v dd 5.5v, v ss = 0v; c agc = 4.7 f, c th = 100nf; sel0 = sel1 = v ss ; fixed mode (swen = v ss ); f refosc = 4.8970mhz (equivalent to f rf = 315mhz); data-rate = 1kbps (manchester encoded). t a = 25c, bold values indicate ?40c t a +85c; current flow into devic e pins is positive; unless noted. symbol parameter condition min typ max units continuous operation, f rf = 315mhz 2.2 3.2 ma i op operating current polled with 10:1 duty cycle, f rf = 315mhz 220 a continuous operation, f rf = 433.92mhz 3.5 ma polled with 10:1 duty cycle, f rf = 433.92mhz 350 a i stby standby current v shut = v dd 0.9 a rf section, if section receiver sensitivity ( note 4 ) f rf = 315mhz ?97 dbm f rf = 433.92mhz ?95 dbm f if if center frequency note 6 0.86 mhz f bw if bandwidth note 6 0.43 mhz maximum receiver input r sc = 50 ? ?20 dbm spurious reverse isolation ant pin, r sc = 50 ? , note 5 30 v rms agc attack to decay ratio t attack t decay 0.1 agc leakage current t a = +85c 100 na reference oscillator z refosc reference oscillator input impedance note 8 290 k ? reference oscillator source current 5.2 a demodulator z cth cth source impedance note 7 145 k ? i zcth(leak) cth leakage current t a = +85c 100 na demodulator filter bandwidth sweep mode (swen = vdd or open) note 6 v sel0 = v dd . v sel1 = v dd v sel0 = v ss . v sel1 = v dd v sel0 = v dd . v sel1 = v ss v sel0 = v ss . v sel1 = v ss 4000 2000 1000 500 hz hz hz hz demodulator filter bandwidth fixed mode (swen = vss) note 6 v sel0 = v dd . v sel1 = v dd v sel0 = v ss . v sel1 = v dd v sel0 = v dd . v sel1 = v ss v sel0 = v ss . v sel1 = v ss 8000 4000 2000 1000 hz hz hz hz
micrel, inc. micrf002/rf022 july 2008 5 m9999-070808 symbol parameter condition min typ max units digital/control section v in(high) input-high voltage sel0, sel1, swen 0.8 v dd v in(low) input-low voltage sel0, sel1, swen 0.2 v dd i out output current do, wakeb pins, push-pull 10 a v out(high) output high voltage do, wakeb pins, i out = ?1 a 0.9 v dd v out(low) output low voltage do, wakeb pins, i out = +1 a 0.1 v dd t r , t f output rise and fall times do, wakeb pins, c load = 15pf 10 s notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive, use approp riate esd precautions. meets class 1 esd te st requirements, (human body model hbm), in accordance with mil-std-883c, method 3015. do not operate or store near strong electrostatic fields. 4. sensitivity is defined as the average si gnal level measured at the input necessary to achieve 10-2 ber (bit error rate). th e rf input is assumed to be matched to 50 ? . 5. spurious reverse isolation repres ents the spurious components which appear on t he rf input pin (ant) measured into 50 ? with an input rf matching network. 6. parameter scales linearly with reference oscillator frequency f t . for any reference oscillator fr equency other than 4.8970mhz, compute new parameter value as the ratio:. 4.8970mhz) at value (parameter 4.8970mhz mhz refosc f 7. parameter scales inversely with reference oscillator frequency f t . for any reference oscillator frequency other than 4.8970mhz, compute new parameter value as the ratio: 4.8970mhz) at value (parameter mhz refosc f 4.8970mhz 8. series resistance of the resonator (cer amic resonator or crystal) should be minimized to the extent possible. in cases whe re the resonator series resistance is too great, the oscillator may oscillate at a diminished peak-to-peak level, or may fail to oscillate entirel y. micrel recommends that series resistances for ceramic resona tors and crystals not exceed 50ohms and 100 ? respectively. refer to application hint 35 for crystal recommendations.
micrel, inc. micrf002/rf022 july 2008 6 m9999-070808 typical characteristics 1.5 3.0 4.5 6.0 250 300 350 400 450 500 current (ma) frequency (mhz) supply current vs. frequency t a =25 c v dd =5v sweep mode, continuous operation 1.5 2.0 2.5 3.0 3.5 -40 -20 0 20 40 60 80 100 current (ma) temperature ( c) supply current vs. temperature f = 315mhz v dd =5v sweep mode, continuous operation
micrel, inc. micrf002/rf022 july 2008 7 m9999-070808 functional diagram peak detector agc control 2nd order programmable low-pass filter 5th order band-pass filter synthesizer control logic r sc resettable counter reference oscillator cystal or ceramic resonator cagc ant sel0 vdd vss sel1 swen refosc 430khz switched- capacitor resistor wakeb cth do micrf002 rf amp if amp if amp compa- rator wakeup reference and control uhf downconverter ook demodulator f rx f lo f if shut c agc c th f t figure 1. micrf002 block diagram application informat ion and functional description refer to figure 1 ?micrf002 block diagram?. identified in the block diagram are the four sections of the ic: uhf downconverter, ook demodulator, reference and control, and wakeup. also shown in the figure are two capacitors (cth, cagc) and one timing component, usually a crystal or ceramic resonator. with the exception of a supply decoupling capacitor, and antenna impedance matching network, these are the only external components needed by the micrf002 to assemble a complete uhf receiver. for optimal performance is highly recommended that the micrf002 is impedance matched to the antenna, the matching network will add an additional two or three components. four control inputs are shown in the block diagram: sel0, sel1, swen, and shut. using these logic inputs, the user can control the operating mode and selectable features of the ic. these inputs are cmos compatible, and are internally pulled-up. if bandpass filter roll-off response of the if filter is 5th order, while the demodulator data filter exhibits a 2 nd order response. design steps the following steps are the basic design steps for using the micrf002 receiver: 1. select the operating mode (sweep or fixed) 2. select the reference oscillator 3. select the c th capacitor 4. select the c agc capacitor 5. select the demodulator filter bandwidth step 1: selecting the operating mode fixed-mode operation for applications where the transmit frequency is accurately set (that is, applications where a saw or crystal-based transmitter is used) the micrf002 may be configured as a standard superheterodyne receiver (fixed mode). in fixed- mode operation the rf bandwidth is narrower making the receiver less susceptible to interfering signals. fixed mode is selected by connecting swen to ground. sweep-mode operation when used in conjunction with low-cost l-c transmitters the micrf002 should be configured in sweep-mode. in sweep-mode, while the topology is still superheterodyne, the lo (local oscillator) is swept over a range of frequencies at rates greater than the data rate. this technique effectively increases the rf bandwidth of the
micrel, inc. micrf002/rf022 july 2008 8 m9999-070808 micrf002, allowing the device to operate in applications where significant transmitter-receiver frequency misalignment may exist. the transmit frequency may vary up to 0.5% over initial tolerance, aging, and temperature. in sweep-mode a band approximately 1.5% around the nominal transmit frequency is captured. the transmitter may drift up to 0.5% without the need to retune the receiver and without impacting system performance. the swept-lo technique does not affect the if bandwidth, therefore noise performance is not degraded relative to fixed-mode. the if bandwidth is 430khz whether the device is operating in fixed- or sweep-mode. due to limitations imposed by the lo sweeping process, the upper limit on data rate in sweep mode is approximately 5.0kbps. similar performance is not currently available with crystalbased superheterodyne receivers which can operate only with saw- or crystal-based transmitters. in sweep- mode, a range reduction will o ccur in installations where there is a strong interferer in the swept rf band. this is because the process indiscriminately includes all signals within the sweep range. an micrf002 may be used in place of a superregenerative receiver in most applications. step 2: selecting the reference oscillator all timing and tuning operations on the micrf002 are derived from the internal colpitts reference oscillator. timing and tuning is controlled through the refosc pin in one of three ways: 1. connect a ceramic resonator 2. connect a crystal 3. drive this pin with an external timing signal the specific reference frequency required is related to the system transmit frequency and to the operating mode of the receiver as set by the swen pin. crystal or ceramic resonator selection do not use resonators with integral capacitors since capacitors are included in the ic, also care should be taken to ensure low esr capacitors are selected. application hint 34 and application hint 35 provide additional information and recommended sources for crystals and resonators. if operating in fixed-mode, a crystal is recommended. in sweep-mode either a crystal or ceramic resonator may be used. when a crystal of ceramic resonator is used the minimum voltage is 300mv pp . if using an externally applied signal it should be ac-coupled and limited to the operating range of 0.1v pp to 1.5v pp . selecting reference oscillator frequency f t (fixed- mode) as with any superheterodyne receiver, the mixing between the internal lo (local oscillator) frequency f lo and the incoming transmit frequency f tx ideally must equal the if center frequency. equation 1 may be used to compute the appropriate f lo for a given f tx : (1) ? ? ? ? ? ? ? ? = 315 f 0.86 f f tx tx lo frequencies f tx and f lo are in mhz. note that two values of f lo exist for any given f tx , distinguished as ?high-side mixing? and ?low-side mixing?. high-side mixing results in an image frequency above the frequency of interest and low-side mixing results in a frequency below. after choosing one of the two acceptable values of f lo , use equation 2 to compute the reference oscillator frequency f t : (2) 64.5 f f lo t = frequency f t is in mhz. connect a crystal of frequency f t to refosc on the micrf002. four-decimal-place accuracy on the frequency is generally adequate. the following table identifies f t for some common transmit frequencies when the micrf002 is operated in fixed mode. transmit frequency f tx reference oscillator frequency f t 315mhz 4.8970mhz 390mhz 6.0630mhz 418mhz 6.4983mhz 433.92mhz 6.7458mhz table 2. fixed-mode reco mmended reference oscillator values for typical transmit frequencies (high-side mixing) selecting refosc frequency f t (sweep-mode) selection of the reference oscillator frequency f t in sweep- mode is much simpler than in fixed mode due to the lo sweeping process. also, accuracy requirements of the frequency reference component are significantly relaxed. in sweep-mode, f t is given by equation 3: (3) 64.25 f f lo t = in sweep-mode a reference oscillator with frequency accurate to two-decimal-places is generally adequate. a crystal may be used and may be necessary in some cases if the transmit frequency is particularly imprecise. transmit frequency f tx reference oscillator frequency f t 315mhz 4.88mhz 390mhz 6.05mhz 418mhz 6.48mhz 433.92mhz 6.73mhz table 3. sweep-mode recommended reference oscillator values for typical transmit frequencies
micrel, inc. micrf002/rf022 july 2008 9 m9999-070808 step 3: selecting the c th capacitor extraction of the dc value of the demodulated signal for purposes of logic-level data slicing is accomplished using the external threshold capacitor c th and the on- chip switched capacitor ?resistor? r sc , shown in the block diagram. slicing level time constant values vary somewhat with decoder type, data pattern, and data rate, but typically values range from 5ms to 50ms. optimization of the value of c th is required to maximize range. selecting capacitor c th the first step in the process is selection of a data-slicing- level time constant. this selection is strongly dependent on system issues including system decode response time and data code structure (that is, existence of data preamble, etc.). this issue is covered in more detail in application note 22. the effective resistance of r sc is listed in the electrical characteristics table as 145k ? at 315mhz, this value scales linearly with frequency. source impedance of the c th pin at other frequencies is given by equation 4, where f t is in mhz: (4) t sc f 4.8970 145k ? r = of 5x the bit-rate is recommended. assuming that a slicing level time constant has been established, capacitor c th may be computed using equation 5: (5) sc th r c = a standard 20% x7r ceramic capacitor is generally sufficient. refer to application hint 42 for c th and cagc selection examples. step 4: selecting the c agc capacitor the signal path has agc (automatic gain control) to increase input dynamic range. the attack time constant of the agc is set externally by the value of the c agc capacitor connected to the c agc pin of the device. to maximize system range, it is important to keep the agc control voltage ripple low, preferably under 10mv pp once the control voltage has attained its quiescent value. for this reason capacitor values of at least 0.47 f are recommended. the agc control voltage is carefully managed on-chip to allow duty-cycle operation of the micrf002. when the device is placed into shutdown mode (shut pin pulled high), the agc capacitor floats to retain the voltage. when operation is resumed, only the voltage droop due to capacitor leakage must be replenished. a relatively low- leakage capacitor is recommended when the devices are used in dutycycled operation. to further enhance duty-cycled operation, the agc push and pull currents are boosted for approximately 10ms immediately after the device is taken out of shutdown. this compensates for agc capacitor voltage droop and reduces the time to restore the correct agc voltage. the current is boosted by a factor of 45. selecting c agc capacitor in continuous mode a c agc capacitor in the range of 0.47 f to 4.7 f is typically recommended. the value of the c agc should be selected to minimize the ripple on the agc control voltage by using a sufficiently large capacitor. however if the capacitor is too large the agc may react too slowly to incoming signals. agc settling time from a completely discharged (zero-volt) state is given approximately by equation 6: (6) 0.44 1.333c ? t agc ? = where: c agc sin in f, and ? t is in seconds. selecting c agc capacitor in duty-cycle mode voltage droop across the c agc capacitor during shutdown should be replenished as quickly as possible after the ic is enabled. as mentioned above, the micrf002 boosts the push-pull current by a factor of 45 immediately after start- up. this fixed time period is based on the reference oscillator frequency f t . the time is 10.9ms for f t = 6.00mhz, and varies inversely with f t . the value of c agc capacitor and the duration of the shutdown time period should be selected such that the droop can be replenished within this 10ms period. polarity of the droop is unknown, meaning the agc voltage could droop up or down. worst-case from a recovery standpoint is downward droop, since the agc pull-up current is 1/10th magnitude of the pulldown current. the downward droop is replenished according to the equation 7: (7) ? t ? v c i agc = where: i = agc pullup current for the initial 10ms (67.5 a) c agc = agc capacitor value ? t = droop recovery time ? v = droop voltage for example, if user desires ? t = 10ms and chooses a 4.7 f c agc , then the allowable droop is about 144mv. using the same equation with 200na worst case pin leakage and assuming 1 a of capacitor leakage in the same direction, the maximum allowable ? t (shutdown time) is about 0.56s for droop recovery in 10ms. the ratio of decay-to-attack time-constant is fixed at 10:1 (that is, the attack time constant is 1/10th of the decay time constant). generally the design value of 10:1 is adequate
micrel, inc. micrf002/rf022 july 2008 10 m9999-070808 for the vast majority of applications. if adjustment is required the constant may be varied by adding a resistor in parallel with the c agc capacitor. the value of the resistor must be determined on a case by case basis. step 5: selecting the demod filter bandwidth the inputs sel0 and sel1 control the demodulator filter bandwidth in four binary steps (625hz to 5000hz in sweep, 1250hz to 10000hz in fixed-mode), see table 3. bandwidth must be selected according to the application. the demodulator bandwidth should be set according to equation 8: (8) width pulse shortest 0.65 bandwidth demoulator ? = it should be noted that the values indicated in table 1 are nominal values. the filter bandwidth scales linearly with frequency so the exact value will depend on the operating frequency. refer to the ?electrical characteristics? for the exact filter bandwidth at a chosen frequency. demodulator bandwidth sel0 sel1 sweep-mode fixed-mode 1 1 5000hz 10000hz 0 1 2500hz 5000hz 1 0 1250hz 2500hz 0 0 625hz 1250hz table 1. nominal demodulator filter bandwidth vs. sel0, sel1 and operating mode
micrel, inc. micrf002/rf022 july 2008 11 m9999-070808 additional applications information in addition to the basic operation of the micrf002 the following enhancements can be made. in particular it is strongly recommended that the antenna impedance is matched to the input of the ic. antenna impedance matching as shown in table 4 the antenna pin input impedance is frequency dependant. the ant pin can be matched to 50 ? with an l-type circuit. that is, a shunt inductor from the rf input to ground and another in series from the rf input to the antenna pin. inductor values may be different from table depending on pcb material, pcb thickness, ground configuration, and how long the traces are in the layout. values shown were characterized for a 0.031 thickness, fr4 board, solid ground plane on bottom layer, and very short traces. murata and coilcraft wire wound 0603 or 0805 surface mount inductors were tested, however any wire wound inductor with high srf (self resonance frequency) should do the job. shutdown function duty-cycled operation of the micrf002 (often referred to as polling) is achieved by turning the micrf002 on and off via the shut pin. the shutdown function is controlled by a logic state applied to the shut pin. when vshut is high, the device goes into low-power standby mode. this pin is pulled high internally, it must be externally pulled low to enable the receiver. l shunt l series j100 j25 50 0 ?j25 ?j100 frequency (mhz) z in z11 s11 l shunt (nh) l series (nh) 300 12-j166 0.803-j0.529 15 72 305 12-j165 0.800-j0.530 15 72 310 12-j163 0.796-j0.536 15 72 315 13-j162 0.791-j0.536 15 72 320 12-j160 0.789-j0.543 15 68 325 12-j157 0.782-j0.550 12 68 330 12-j155 0.778-j0.556 12 68 335 12-j152 0.770-j0.564 12 68 340 11-j150 0.767-j0.572 15 56 345 11-j148 0.762-j0.578 15 56 350 11-j145 0.753-j0.586 12 56 355 11-j143 0.748-j0.592 12 56 360 11-j141 0.742-j0.597 10 56 365 11-j139 0.735-j0.603 10 56 370 10-j137 0.732-j0.612 12 47 375 10-j135 0.725-j0.619 12 47 380 10-j133 0.718-j0.625 10 47 385 10-j131 0.711-j0.631 10 47 390 10-j130 0.707-j0.634 10 43 395 10-j128 0.700-j0.641 10 43 400 10-j126 0.692-j0.647 10 43 405 10-j124 0.684-j0.653 10 39 410 10-j122 0.675-j0.660 10 39 415 10-j120 0.667-j0.667 10 39 420 10-j118 0.658-j0.673 10 36 425 10-j117 0.653-j0.677 10 36 430 10-j115 0.643-j0.684 10 33 435 10-j114 0.638-j0.687 10 33 440 8-j112 0.635-j0.704 8.2 33 table 4. input impedance vs. frequency
micrel, inc. micrf002/rf022 july 2008 12 m9999-070808 power supply bypass capacitors v ddbb and v ddrf should be connected together directly at the ic pins. supply bypass capacitors are strongly recommended. they should be connected to v ddbb and v ddrf and should have the shortest possible lead lengths. for best performance, connect v ssrf to v ssbb at the power supply only (that is, keep v ssbb currents from flowing through the v ssrf return path). increasing selectivity with an optional bandpass filter for applications located in high ambient noise environments, a fixed value band-pass network may be connected between the ant pin and v ssrf to provide additional receive selectivity and input overload protection. a minimum input configuration is included in figure 7 it provides some filtering and necessary overload protection. data squelching during quiet periods (no signal) the data output (do pin) transitions randomly with noise. most decoders can discriminate between this random noise and actual data but for some system it does present a problem. there are three possible approaches to reducing this output noise: 1. analog squelch to raise the demodulator threshold 2. digital squelch to disable the output when data is not present 3. output filter to filter the (high frequency) noise glitches on the data output pin. the simplest solution is add analog squelch by introducing a small offset, or squelch voltage, on the c th pin so that noise does not trigger the internal comparator. usually 20mv to 30mv is sufficient, and may be achieved by connecting a several-megohm resistor from the c th pin to either v ss or v dd , depending on the desired offset polarity. since the micrf002 has receiver agc noise at the internal comparator input is always the same, set by the agc. the squelch offset requirement does not change as the local noise strength changes from installation to installation. introducing sque lch will reduce sensitivity and also reduce range. only introduce an amount of offset sufficient to quiet the output. ty pical squelch resistor values range from 6.8m ? to 10m ? . wake-up function the wakeb output signal can be used to reduce system power consumption by enabling the rest of a system when an rf signal is present. the wakeb is an output logic signal which goes active low when the ic detects a constant rf carrier. the wake-up function is unavailable when the ic is in shutdown mode. to activate the wake-up function, a received constant rf carrier must be present for 128 counts or the internal system clock. the internal system clock is derived from the reference oscillator and is 1/256 the reference oscillator frequency. for example: f t = 6.4mhz f s = f t /256 = 25khz p s = 1/f s = 0.04ms 128 counts x 0.04ms = 5.12ms where: f t = reference oscillator frequency f s = system clock frequency p s = system clock period the wake-up counter will re set immediately after a detected rf carrier drops. the duration of the wake-up signal output is then determined by the required wake up time plus an additional rf carrier on time interval to create a wake up pulse output. wakeb output pulse time = t wake + additional rf carrier on time for designers who wish to use the wakeup function while squelching the output, a positive squelching offset voltage must be used. this simply requires that the squelch resistor be connected to a voltage more positive than the quiescent voltage on the c th pin so that the data output is low in absence of a transmission. i/o pin interface circuitry interface circuitry for the various i/o pins of the micrf002 are diagrammed in figures 1 through 6. the esd protection diodes at all input and output pins are not shown. c th pin phi2b phi1b phi1 phi2 cth demodulator signal 2.85vdc vddbb vssbb vssbb figure 2. cth pin figure 2 illustrates the c th pin interface circuit. the c th pin is driven from a p-channel mosfet source-follower with approximately 10 a of bias. transmission gates tg1 and tg2 isolate the 6.9pf capacitor. internal control signals phi1/phi2 are related in a manner such that the impedance across the transmission gates looks like a ?resistance? of approximately 100k ? . the dc potential at the c th pin is approximately 1.6v
micrel, inc. micrf002/rf022 july 2008 13 m9999-070808 c agc pin vddbb vssbb 675a 67.5a compa- rator 1.5a 15a timout cag c figure 3. cagc pin figure 3 illustrates the c agc pin interface circuit. the agc control voltage is developed as an integrated current into a capacitor c agc . the attack current is nominally 15 a, while the decay current is a 1/10th scaling of this, nominally 1.5 a, making the attack/decay time constant ratio a fixed 10:1. signal gain of the rf/if strip inside the ic diminishes as the voltage at c agc decreases. modification of the attack/decay ratio is possible by adding resistance from the c agc pin to either v ddbb or v ssbb , as desired. both the push and pull current sources are disabled during shutdown, which maintains the voltage across c agc , and improves recovery time in duty-cycled applications. to further improve duty-cycle recovery, both push and pull currents are increased by 45 times for approximately 10ms after release of the shut pin. this allows rapid recovery of any voltage droop on c agc while in shutdown. do and wakeb pins vddbb vssbb compa- rator 10a 10a do figure 4. do and wakeb pins the output stage for do (digital output) and wakeb (wakeup output) is shown in figure 4. the output is a 10 a push and 10 a pull switched-current stage. this output stage is capable of driving cmos loads. an external buffer- driver is recommended for driving high-capacitance loads. refosc pin 250 200k active bias refosc 30pf 30pf 30a vddbb vssbb vssb b figure 5. refosc pin the refosc input circuit is shown in figure 5. input impedance is high (200k ? ). this is a colpitts oscillator with internal 30pf capacitors. this input is intended to work with standard ceramic resonators connected from this pin to the v ssbb pin, although a crystal may be used when greater frequency accuracy is required. the nominal dc bias voltage on this pin is 1.4v. sel0, sel1, swen, and shut pins to interna l circuits vddbb vssbb sel0, sel1, swen q2 q3 q1 vssbb shut q4 figure 6a. sel0, sel1, swen pins to interna l circuits vddbb vssbb shut q2 q3 q1 vssbb figure 6b. shut pin control input circuitry is shown in figures 6a and 6b. the standard input is a logic inverter constructed with minimum geometry mosfets (q2, q3). p-channel mosfet q1 is a large channel length device which functions essentially as a ?weak? pullup to v ddbb . typical pull-up current is 5 a, leading to an impedance to the v ddbb supply of typically 1m ? .
micrel, inc. micrf002/rf022 july 2008 14 m9999-070808 applications example 315mhz receiver/decoder application figure 7 illustrates a typical application for the micrf002 uhf receiver ic. this receiver operates continuously (not duty cycled) in sweep mode, and features 6-bit address decoding and two output code bits. operation in this example is at 315mhz, and may be customized by selection of the appropriate frequency reference (y1), and adjustment of the antenna length. the value of c4 would also change if the optional input filter is used. changes from the 1kb/s data rate may require a change in the value of r1. a bill of materials accompanies the schematic. sel0 sel0 swen vssrf refosc vssrf sel1 ant cagc vddrf wakeb vddbb shut cth do nc vssbb c2 2.2f 4.8970mhz y1 u1 micrf002 4.7f optional filter 8.2pf, 16.6nh pcb foil inductor 1in of 30mil trace c4 l1 +5v supply input c1 4.7f a0 vdd a1 vt a2 osc1 a3 osc2 a4 din a5 d11 a6 d10 a7 d9 u2 ht-12d vss d8 r1 68k r2 1k code bit 0 code bit 1 rf (analog) ground baseband (digital) ground 0.4 monopole antenna (11.6in) 6-bit address figure 7. 315mhz, 1kbps on-off keyed recwiver/decoder bill of materials item part number manufacturer description qty. c1 vishay (1) 4.7f, dipped tantalum capacitor 1 c2 vishay (1) 2.2f, dipped tantalum capacitor 1 c3 vishay (1) 4.7f, dipped tantalum capacitor 1 c4 vishay (1) 8.2pf, cog ceramic capacitor 1 cr1 csa6.00mg murata (2) 6.00mhz, ceramic resonator 1 d1 ssf-lx100lid lumex (3) red led 1 r1 68k, 1/4w, 5% 1 r2 vishay (1) 1k, 1/4w, 5% 1 u1 micrf002 micrel, inc. (4) 300-440mhz qwikradio ? ask receiver 1 u2 ht-12d holtek (5) logic decoder 1 notes: 1. vishay tel: (203) 268-6261 2. murata tel: (800) 241-6574, fx: (770) 436-3030 3. lumex tel: (800) 278-5666, fx: (847) 359-8904 5. micrel, inc.: (408) 944-0800 5. holtek tel: (408) 894-9046, fx: (408) 894-0838
micrel, inc. micrf002/rf022 july 2008 15 m9999-070808 pcb layout information the micrf002 evaluation board was designed and characterized using two sided 0.031 inch thick fr4 material with 1 ounce copper clad. if another type of printed circuit board material were to be substituted, impedance matching and characterization data stated in this document may not be valid. the gerber files for this board can be downloaded from the micrel website at www.micrel.com. pcb silk screen pcb component side layout pcb solder side layout r2 10k c3(cth) 0.047f c2 0.1f c1 4.7f c4(c agc ) 4.7f y1 6.7458mhz micrf002 ref.osc. gnd shut gnd do gnd j2 jp2 j5 j4 c5 (not placed) jp3 jp1 +5v gnd j3 j1 rf input z2 squelch resistor (not placed) 5 6 7 8 12 11 10 9 1 2 3 4 16 15 14 13 sel0 vssrf vssrf ant vddrf vddbb cth nc swen refosc sel1 cagc wakeb shut do vssbb z1 r1 z4 z3
micrel, inc. micrf002/rf022 july 2008 16 m9999-070808 package information 16-pin soic (m) 8-pin soic (m)
micrel, inc. micrf002/rf022 july 2008 17 m9999-070808 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 data sheet is belie ved to be accurate and reliable. however, no responsibility is a ssumed by micrel for its use. micrel reserves the right to change circuitry and specifications at any time without notification to the customer. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product can reasonably be expected to result in personal injury. life suppo rt devices or systems are devices or systems that (a) are in tended 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 significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2003 micrel, incorporated.

▲Up To Search▲

Price & Availability of MICRF002YM-FS12

	To Download MICRF002YM-FS12 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .