MICRF007 Micrel MICRF007 QwikRadio™ Low-Power UHF Receiver Preliminary Information General Description Features The MICRF007 is a single chip ASK/OOK (ON-OFF Keyed) Receiver IC for remote wireless applications, employing Micrel’s latest QwikRadiotm technology. 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 production costs. The result is a highly reliable yet extremely low cost solution. The MICRF007 is an enhanced version of the MICRF002 and MICRF011. The MICRF007 is a conventional superhetrodyne receiver, with an (internal) Local oscillator fixed at a single frequency based on an external reference crystal or clock. As with any conventional superhetrodyne reciever, the transmit frequency must be accurately controlled, generally with a crystal or SAW (Surface Acoustic Wave) resonator. The MICRF007 provides two feature enhancements over the MICRF001/011, (1) a Shutdown Mode, which may be used for duty-cycle operation. (2) Reduced current consumption. The MICRF007 requires a mere 1.7mA at 315MHz (3.0mA at 433.92MHz).These features make the MICRF007 ideal for low and ultra-low power applications, such as RKE and RFID. All post-detection (demodulator) data filtering is provided on the MICRF007, so no external baseband filters are required. The demodulator filter bandwidth is set to 2.1kHz. Data rates up to 2kbps may be used • • • • • • • • • Complete UHF receiver on a monolithic chip 300MHz Data Rates up to 2.1kbps Automatic tuning, no manual adjustment Low Power Consumption 315MHz: 1.7 mA fully operational 0.5µA shutdown 170µA polled 433.92MHz: 3.0mA fully operational 0.5µA shutdown 300µA in 10:1 polled operation Very low RF re-radiation at the antenna CMOS logic interface to standard decoder and microprocessor ICs Extremely low external part count No filters or inductors required Applications • • • • Automotive Remote Keyless Entry (RKE) Long Range RF Identification Remote fan and light control Garage door and gate openers Typical Application MICRF007 VSS SEL0 REFOSC ANT CAGC VDDRF SHUT 4.7µF +5V CTH Data Output DO 0.047µF 315MHz 1200b/s On-Off Keyed Receiver QwikRadio is a trademark of Micrel, Inc. Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com December 2000 1 MICRF007 MICRF007 Micrel Ordering Information Part Number Demodulator Bandwidth Package MICRF007BM 2100Hz 8-Pin SOIC Other voltages available. Contact Micrel for details. Pin Configuration MICRF007BM VSS 1 8 REFOSC ANT 2 7 CAGC VDD 3 6 SHUT CTH 4 5 DO 8-Pin SOP (M) Package MICRF007 2 December 2000 MICRF007 Micrel Pin Description Pin Number Pin Name 1 VSS Ground Return (Input): Ground return to the power supply. See “Application Information” for bypass capacitor details. 2 ANT Antenna (Input): High-impedance, internally ac coupled receiver input. Connect this pin to the receive antenna. This FET gate input has approximately 2pF of shunt (parasitic) capacitance. See “Applications Information” for optional band-pass filter information. 3 VDD Power Supply (Input): Positive supply input for the RF IC. Connect a low ESL, low ESR decoupling capacitor from this pin to VSS, lead lengths should be as short as possible. 4 CTH [Data Slicing] Threshold Capacitor (External Component): Capacitor extracts the dc average value from the demodulated waveform which becomes the reference for the internal data slicing comparator. See “Applications Information” for selection. 5 DO Digital Output (Output): CMOS-level compatible data output signal. 6 SHUT Shutdown (Input): Shutdown-mode logic-level control input. Pull low to enable the receiver. This input has an internal pulled-up to VDD. 7 CAGC AGC Capacitor (External Component): Integrating capacitor for on-chip AGC (automatic gain control). The decay/attack time-constant (t) ratio is nominally 10:1. See “Applications Information” for capacitor selection. 8 REFOSC December 2000 Pin Function Reference Oscillator (External Component or Input): Timing reference for on-chip tuning and alignment. Connect a crystal between this pin and VSS, or drive the input with an ac-coupled 0.5Vpp input clock. 3 MICRF007 MICRF007 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (VDDRF, VDDBB) .................................... +7V Input/Output Voltage (VI/O) ................. VSS–0.3 to VDD+0.3 Junction Temperature (TJ) ...................................... +150°C Storage Temperature Range (TS) ............ –65°C to +150°C Lead Temperature (soldering, 10 sec.) ................... +260°C ESD Rating, Note 3 Supply Voltage (VDD, VDDBB) .................... +4.75V to +5.5V Ambient Temperature (TA) ......................... –40°C to +85°C Package Thermal Resistance (θJA) 16-pin DIP (θJA) ................................................... 90°C/W 16-pin SOIC (θJA) .............................................. 120°C/W Electrical Characteristics VDDRF = VDDBB = VDD where +4.75V ≤ VDD ≤ 5.5V, VSS = 0V; CAGC = 4.7µF, CTH = 0.047µF; fREFOSC = 4.90MHz; TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C; current flow into device pins is positive; unless noted. Symbol Parameter Condition Min IOP Operating Current continuous operation Typ Max Units 3 5.5 mA 10:1 duty cycle 300 µA VSHUT = VDD 0.5 µA Receiver Sensitivity Notes 4, 6 –96 fIF IF Center Frequency Note 7 0.86 MHz fBW IF 3dB Bandwidth Notes 6, 7 0.43 kHz fANT RF Input Range 300 440 MHz Receive Modulation Duty-Cycle 20 80 % –20 dBm ISTBY Standby Current RF Section, IF Section 400 Maximum Receiver Input RSC = 50Ω Spurious Reverse Isolation ANT pin, RSC = 50Ω, Note 5 AGC Attack to Decay Ratio tATTACK ÷ tDECAY 0.1 AGC Leakage Current TA = +85°C 100 to 1% of final value 2.5 –90 dBm µVrms 1 nA Reference Oscillator Reference Oscillator Stabilization Time ZREFOSC Reference Oscillator Input Impedance 3.1 290 Reference Oscillator Input Range 0.1 Reference Oscillator Source Current 4.5 2.8 ms kΩ 1.5 VP-P 5.2 µA 110 kΩ Demodulator ZCTH CTH Source Impedance ∆ZCTH CTH Source Impedance Variation IZCTH(leak) CTH Leakage Current TA = +85°C ±100 nA Demodulator Filter Bandwidth VSEL0 = VSEL1 = VSWEN = VDD, Notes 7, 9 4160 Hz Demodulator Filter Bandwidth VSEL0 = VSEL1 = VDD, VSWEN = VSS, Notes 5, 7, 9 8320 Hz MICRF007 Note 8 –15 4 +15 % December 2000 MICRF007 Symbol Micrel Parameter Condition Min Typ Max Units Digital/Control Section IIN(pu) Input Pull-Up Current SEL0, SEL1, SWEN, VSHUT = VSS VIN(high) Input-High Voltage SEL0, SEL1, SWEN VIN(low) Input-Low Voltage SEL0, SEL1, SWEN IOUT Output Current DO, WAKEB pins, push-pull VOUT(high) Output High Voltage DO, WAKEB pins, IOUT = –1µA VOUT(low) Output Low Voltage DO, WAKEB pins, IOUT = +1µA tR, tF Output Rise and Fall Times DO, WAKEB pins, CLOAD = 15pF µA 8 0.8VDD 0.2VDD V V µA 10 0.9VDD V 0.1VDD V 10 µs 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. Use appropriate ESD precautions. Meets class 1 ESD test requirements, (human body model HBM), in accordance with MIL-STD-883C, method 3015. Do not operate or store near strong electrostatic fields. Note 4: Sensitivity is defined as the average signal level measured at the input necessary to achieve 10-2 BER (bit error rate). The input signal is defined as a return-to-zero (RZ) waveform with 50% average duty cycle (Manchester encoded data) at a data rate of 300b/s. The RF input is assumed to be matched into 50Ω. Note 5: Spurious reverse isolation represents the spurious components which appear on the RF input pin (ANT) measured into 50Ω with an input RF matching network. Note 6: Sensitivity, a commonly specified receiver parameter, provides an indication of the receiver’s input referred noise, generally input thermal noise. However, it is possible for a more sensitive receiver to exhibit range performance no better than that of a less sensitive receiver if the background noise is appreciably higher than the thermal noise. Background noise refers to other interfering signals, such as FM radio stations, pagers, etc. A better indicator of achievable receiver range performance is usually given by its selectivity, often stated as intermediate frequency (IF) or radio frequency (RF) bandwidth, depending on receiver topology. Selectivity is a measure of the rejection by the receiver of “ether” noise. More selective receivers will almost invariably provide better range. Only when the receiver selectivity is so high that most of the noise on the receiver input is actually thermal will the receiver demonstrate sensitivity-limited performance. Note 7: Parameter scales linearly with reference oscillator frequency fT. For any reference oscillator frequency other than 4.90MHz, compute new parameter value as the ratio: fREFOSCMHz × (parameter value at 4.90MHz) 4.90 Example: For reference oscillator freqency fT = 6.00MHz: 6.00 (parameter value at 6.00MHz) = × (paramter value at 4.90MHz) 4.90 Note 8: Parameter scales inversely with reference oscillator frequency fT. For any reference oscillator frequency other than 4.90MHz, compute new parameter value as the ratio: 4.90 × (parmeter value at 4.90MHz) fREFOSCMHz Example: For reference oscillator frequency fT = 6.00MHz: 4.90 (parmeter value at 6.00MHz) = × (parmeter value at 4.90MHz) 6.00 Note 9: Demodulator filter bandwidths are related in a binary manner, so any of the (lower) nominal filter values may be derived simply by dividing this parameter value by 2, 4, or 8 as desired. December 2000 5 MICRF007 MICRF007 Micrel Typical Characteristics Supply Current vs. Frequency Supply Current vs. Temperature 3.5 6.0 CURRENT (mA) CURRENT (mA) TA = 25°C VDD = 5V 4.5 3.0 Sweep Mode, Continuous Operation 3.0 2.5 2.0 1.5 -40 -20 1.5 300 325 350 375 400 425 450 FREQUENCY (MHz) MICRF007 f = 315MHz VDD = 5V Sweep Mode, Continuous Operation 0 20 40 60 80 100 TEMPERATURE (°C) 6 December 2000 MICRF007 Micrel Functional Diagram CAGC AGC Control CAGC ANT 2nd Order Programmable Low-Pass Filter 5th Order Band-Pass Filter RF Amp f RX fIF IF Amp IF Amp SwitchedCapacitor Resistor Peak Detector RSC fLO 430kHz Comparator VDD VSS DO CTH Programmable Synthesizer UHF Downconverter OOK Demodulator CTH Control Logic SHUT fT REFOSC Cystal or Ceramic MICRF002 Resonator Reference Oscillator Reference and Control MICRF007 Block Diagram Data Slicing Level Extraction of the dc value of the demodulated signal for purposes of logic-level data slicing is accomplished using the external threshold capacitor CTH and the on-chip switchedcapacitor “resistor” RSC, shown in the block diagram. The effective resistance of RSC is 118kΩ. 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 CTH is required to maximize range. Automatic Gain Control The signal path has AGC (automatic gain control) to increase input dynamic range. An external capacitor, CAGC, must be connected to the CAGC pin of the device. The ratio of decayto-attack time-constant is fixed at 10:1 (that is, the attack time constant is 1/10th of the decay time constant), and this ratio cannot be changed by the user. However, the attack time constant is set externally by choosing a value for CAGC. The AGC control voltage is carefully managed on-chip to allow duty-cycle operation of the MICRF007 in excess of 100:1. 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 on the capacitor due to leakage must be replenished, therefore a relatively low-leakage capacitor is recommended for duty-cycled operation. The actual tolerable leakage will be application dependent. Clearly, leakage performance is less critical when the device off-time is low (milliseconds) and more critical when the off-time is high (seconds). To further enhance duty-cycled operation of the IC, the AGC push and pull currents are increased for a fixed time immediately after the device is taken out of shutdown mode (turnedon). This compensates for AGC capacitor voltage droop while the IC is in shutdown mode, reduces the time to restore the correct AGC voltage, and therefore extends maximum Functional Description Refer to “MICRF007 Block Diagram”. Identified in the block diagram are the three sections of the IC: UHF Downconverter, OOK Demodulator and Reference and Control, and Wakeup. Also shown in the figure are two capacitors (CTH, CAGC) and one timing component (Y1), usually a crystal. With the exception of a supply decoupling capacitor, these are the only external components needed by the MICRF007 to assemble a complete UHF receiver. There is one control input, the SHUT pin. The SHUT function is used to enable the reciever. These inputs are CMOS compatible, and are pulled-up on the IC. Receiver Operation The MICRF007 is a standard superheterodyne receiver with a narrow RF bandwidth IF. The narrow bandwidth receiver is less susceptible to interfering RF signals. The MICRF007 is capable of data rates up to 2.1kbps. Typically a crystal is used for the reference oscillator frequency. The MICRF007 RF center frequency is controlled by a completely integrated PLL / VCO frequency synthesizer which is referenced to the crystal frequency. Since the MICRF007 bandwidth is 430kHz, a tight tolerance transmitter must be used for the system. Typically SAW or crystal based transmitters are used in application designs. IF Bandpass Filter Rolloff response of the IF Filter is 5th order, while the demodulator data filter exhibits a 2nd order response. Baseband Demodulator Filter Bandwidth The MICRF007 has a fully intergrated baseband demodulator filter. The filter has a fixed 2.1kHz bandwidth. This filter limits the reciever raw data rate to 2kbps. December 2000 7 MICRF007 MICRF007 Micrel achievable duty ratios. Push-pull currents are increased by 45 times their nominal values. The fixed time period is based on the reference oscillator frequency fT, 10.9ms for fT = 6.00MHz, and varies inversely as fT varies. Reference Oscillator All timing and tuning operations on the MICRF007 are derived from the internal Colpitts reference oscillator. Timing and tuning is controlled through the REFOSC pin in one of two ways: 1. Connect a crystal 2. Drive this pin with an external timing signal The multiplication factor between the reference oscillator frequency fT and the internal local oscillator (LO) is 64.5×. For fT = fLO = 6.00MHz × 64.5 = 387MHz. MICRF007 The second approach is attractive for lowering system cost further if an accurate reference signal exists elsewhere in the system, for example, a reference clock from a crystal-controlled microprocessor. An externally applied signal should be ac-coupled and resistively-attenuated, or otherwise limited, to approximately 0.5Vpp. The specific reference frequency required is related to the system transmit frequency. Shutdown Function 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, consuming less than 1µA. This pin is pulled high internally. It must be externally pulled low to enable the receiver. 8 December 2000 MICRF007 Micrel Figure 3 illustrates the CAGC pin interface circuit. The AGC control voltage is developed as an integrated current into a capacitor CAGC. The attack current is nominally 15µA, while the decay current is a 1/10th scaling of this, nominally 1.5µA, making the attack/decay timeconstant ratio a fixed 10:1. Signal gain of the RF/IF strip inside the IC diminishes as the voltage at CAGC decreases. Modification of the attack/decay ratio is possible by adding resistance from the CAGC pin to VDD. Both the push and pull current sources are disabled during shutdown, which maintains the voltage across CAGC, 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 CAGC while in shutdown. DO Pin I/O Pin Interface Circuitry Interface circuitry for the various I/O pins of the MICRF007 are diagrammed in Figures 1 through 6. The ESD protection diodes at all input and output pins are not shown. ANT Pin Active Load ANT 50 3pF 6k Active Bias Figure 1a. ANT Pin The ANT pin is internally AC-coupled via a 3pF capacitor, to an RF N-channel MOSFET, as shown in Figure 1. Impedance on this pin to VSS is quite high at low frequencies, and decreases as frequency increases. In the UHF frequency range, the device input can be modeled as 6.3kΩ in parallel with 2pF (pin capacitance) shunt to VSS0RF. VDDBB 10µA Comparator CTH Pin DO VDDBB PHI2B Demodulator Signal 2.85Vdc PHI1B 10µA VSSBB CTH VSSBB PHI2 Figure 4. DO Pin 6.9pF PHI1 VSSBB The output stage for DO (digital output) is shown in Figure 4. The output is a 10µA push and 10µA pull switched-current stage. This output stage is capable of driving CMOS loads. An external buffer-driver is recommended for driving highcapacitance loads. REFOSC Pin Figure 2. CTH Pin Figure 2 illustrates the CTH-pin interface circuit. The CTH pin is driven from a P-channel MOSFET source-follower with approximately 10µA 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 100kΩ. The dc potential at the CTH pin is approximately 1.6V CAGC Pin VDDBB Active Bias 200k REFOSC 30pF 250Ω 30pF VDDBB 30µA VSSBB 1.5µA VSSBB 67.5µA Figure 5. REFOSC Pin Comparator The REFOSC input circuit is shown in Figure 5. Input impedance is high (200kΩ). 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 VSS pin, although a crystal may be used when greater frequency accuracy is required. The nominal dc bias voltage on this pin is 1.4V. CAGC Timout 15µA 675µA VSSBB Figure 3. CAGC Pin December 2000 9 MICRF007 MICRF007 Micrel VDDBB Q1 Q2 to Internal Circuits VSSBB SHUT Q3 VSSBB Figure 6. SHUT Control input circuitry is shown in Figure 6. 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 VDD. Typical pullup current is 5µA, leading to an impedance to the VDD supply of typically 1MΩ. J2 C5 REF.OSC. GND (Not Placed) Y1 6.7458MHz J1 RF INPUT Z1 Z3 Z2 R1 Z4 VSS REFOSC ANT CAGC VDDRF SHUT CTH Squelch Resistor C3(CTH) 0.047µF J3 C1 4.7µF J5 SHUT GND R2 10k J4 (Not Placed) +5V GND DO C4 4.7µF DO GND C2 0.1µF Figure 1. Test Circuit MICRF007 10 December 2000 MICRF007 Micrel PCB Layout Information The MICRF007 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. PCB Silk Screen PCB Component Side Layout December 2000 PCB Solder Side Layout 11 MICRF007 MICRF007 Micrel and “low-side mixing,” and there is generally no preference of one over the other. After choosing one of the two acceptable values of fLO, use Equation 2 to compute the reference oscillator frequency fT: Application Information Transmitter Compatibility Generally, best performance and range will be realized when the MICRF007 is operated in a system using a SAW or crystal based transmitter. The receiver reference oscillator requires the use of a crystal. Bypass Capacitors The power supply bypass capacitors connected to VDD should have the shortest possible lead lengths. For best performance, connect directly to VSS 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 VSS to provide additional receive selectivity and input overload protection. A typical filter is included in Figure 7a. Data Squelching During quiet periods (no signal) the data output (DO pin) transitions randomly with noise, presenting problems for some decoders. A simple solution is to introduce a small offset, or squelch voltage, on the CTH pin so that noise does not trigger the internal comparator. Usually 20mV to 30mV is sufficient, and may be introduced by connecting a severalmegohm resistor from the CTH pin to either VSS or VDD, depending on the desired offset polarity. Since the MICRF007 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 squelch will reduce range modestly. Only introduce an amount of offset sufficient to quiet the output. AGC Configuration By adding resistance from the CAGC pin to VDDBB or VSSBB in parallel with the AGC capacitor, the ratio of decayto-attack time constant may be varied, although the value of such adjustments must be studied on a per-application basis. Generally the design value of 10:1 is adequate for the vast majority of applications. To maximize system range, it is important to keep the AGC control voltage ripple low, preferably under 10mVpp once the control voltage has attained its quiescent value. For this reason capacitor values of at least 0.47µF are recommended. Crystal Selection Selecting Reference Oscillator Frequency fT As with any superheterodyne receiver, the difference between the internal LO (local oscillator) frequency fLO and the incoming transmit frequency fTX ideally must equal the IF center frequency. Equation 1 may be used to compute the appropriate fLO for a given fTX: (1) f fT = LO 64.5 Frequency fT is in MHz. Connect a crystal of frequency fT to REFOSC on the MICRF007. Four-decimal-place accuracy on the frequency is generally adequate. The following table identifies fT for some common transmit frequencies. (2) Reference Oscillator Frequency fT 315MHz 4.8970MHz 390MHz 6.0630MHz 418MHz 6.4983MHz 433.92MHz 6.7458MHz Table 2. Common Transmitter Frequencies External Timing Signals Externally applied signals should be ac-coupled and the amplitude must be limited to approximately 0.5Vpp. Frequency and Capacitor Selection Selection of the slicing level capacitor (CTH), and AGC capacitor (CAGC) are briefly summarized in this section. Selecting Capacitor CTH 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. Source impedance of the CTH pin is given by equation (4), where fT is in MHz: (4) RSC = 118kΩ 4.90 fT Assuming that a slicing level time constant τ has been established, capacitor CTH may be computed using equation (5) C TH = τ RSC A standard ±20% X7R ceramic capacitor is generally sufficient. Selecting CAGC Capacitor in Continuous Mode Selection of CAGC is dictated by minimizing the ripple on the AGC control voltage by using a sufficiently large capacitor. Factory experience suggests that CAGC should be in the vicinity of 0.47µF to 4.7µF. Large capacitor values should be carefully considered as this determines the time required for the AGC control voltage to settle from a completely discharged condition. AGC settling time from a completely discharged (zero-volt) state is given approximately by Equation 6: f fLO = fTX ± 1.064 TX 390 Frequencies fTX and fLO are in MHz. Note that two values of fLO exist for any given fTX, distinguished as “high-side mixing” MICRF007 Transmit Frequency fTX 12 December 2000 MICRF007 (6) Micrel ∆t = 1.333C AGC − 0.44 1/10th magnitude of the pulldown current. The downward droop is replenished according to the Equation 7: where: CAGC is in µF, and ∆t is in seconds. Selecting CAGC Capacitor in Duty-Cycle Mode Generally, droop of the AGC control voltage during shutdown should be replenished as quickly as possible after the IC is “turned-on”. As described in the functional description, for about 10ms after the IC is turned on, the AGC push-pull currents are increased to 45 times their normal values. Consideration should be given to selecting a value for CAGC and a shutdown time period 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 pullup current is December 2000 I (7) C AGC = ∆V ∆t where: I = AGC pullup current for the initial 10ms (67.5µA) CAGC = AGC capacitor value ∆t = droop recovery time ∆V = droop voltage For example, if user desires ∆t = 10ms and chooses a 4.7µF CAGC, then the allowable droop is about 144mV. Using the same equation with 200nA worst case pin leakage and assuming 1µA of capacitor leakage in the same direction, the maximum allowable ∆t (shutdown time) is about 0.56s for droop recovery in 10ms. 13 MICRF007 MICRF007 Micrel 315.0MHz Receiver/Decoder Application Figure 7a illustrates a typical application for the MICRF007 UHF Receiver IC. This receiver operates continuously (not duty cycled), and features 6-bit address decoding and two output code bits. Operation in this example is at 315.5MHz, 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. 0.4 monopole antenna (11.6in) +5V Supply Input Optional Filter 8.2pF, 16.6nH pcb foil inductor 1in of 30mil trace C4 SEL0 VSSRF 6-bit address 4.8970MHz Y1 U1 MICRF002 REFOSC L1 ANT CAGC 4.7µF VDD C1 4.7µF CTH C2 2.2µF SHUT DO U2 HT-12D A0 VDD A1 VT A2 OSC1 A3 OSC2 A4 DIN A5 D11 Code Bit 0 A6 D10 Code Bit 1 A7 D9 VSS D8 R2 1k R1 68k RF Baseband (Analog) (Digital) Ground Ground Figure 7a. 315MHz, 1kb/s On-Off Keyed Receiver/Decoder Item Part Number Manufacturer Description U1 MICRF002 Micrel UHF receiver U2 HT-12D Holtek logic decoder CSA6.00MG Murata 6.00MHz ceramic resonator SSF-LX100LID Lumex red LED CR1 D1 R1 68k 1/4W 5% R2 Vishay 1k 1/4W 5% C1 Vishay 4.7µF dipped tantalum capacitor C3 Vishay 4.7µF dipped tantalum capacitor C2 Vishay 2.2µF dipped tantalum capacitor C4 Vishay 8.2pF COG ceramic capacitor Figure 7b. Bill of Material Vendor Telephone Vishay (203) 268-6261 FAX — Holtek (408) 894-9046 (408) 894-0838 Lumex (800) 278-5666 (847) 359-8904 Murata (800) 241-6574 (770) 436-3030 Figure 7c. Component Vendors MICRF007 14 December 2000 MICRF007 Micrel Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) 0.150 (3.81) DIMENSIONS: INCHES (MM) 0.050 (1.27) TYP 0.064 (1.63) 0.045 (1.14) 0.197 (5.0) 0.189 (4.8) 0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102) 0°–8° SEATING PLANE 45° 0.010 (0.25) 0.007 (0.18) 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79) 8-Lead SOP (M) December 2000 15 MICRF007 MICRF007 Micrel MICREL INC. TEL 1849 FORTUNE DRIVE SAN JOSE, CA 95131 + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 1999 Micrel Incorporated MICRF007 16 December 2000