MICRF112 QwikRadio® UHF ASK/FSK Transmitter General Description Features The MICRF112 is a high performance, easy to use, single chip ASK / FSK Transmitter IC for remote wireless applications in the 300 to 450MHz frequency band. This transmitter IC is a true “data-in, antenna-out” monolithic device. MICRF112 is high performance in three areas: power delivery, operating voltage, and operating temperature. In terms of power, the MICRF112 is capable of delivering +10 dBm into a 50Ω load. This power level enables a small form factor transmitter (lossy antenna) such as a key fob transmitter to operate near the maximum limit of transmission regulations. In terms of operating voltage, the MICRF112 operates from 3.6V to 1.8V. Many transmitter ICs in the same frequency band stop operating below 2.0V. The MICRF112 will work with most batteries to the end of their useful limits. In terms of operating temperature, the MICRF112 operates from -40°C to +125°C. This wide operating temperature range makes MICRF112 an ideal candidate for the demanding applications such as a tire pressure monitoring system. The MICRF112 is easy to use. One only needs a reference frequency (RF carrier frequency divided by 32 times) generated from a crystal with a few additional external parts to create a complete versatile transmitter. The MICRF112 operates with ASK/OOK (Amplitude Shift Keying/On-Off Keyed) UHF receiver types from wide-band super-regenerative radios to narrow-band, high performance super-heterodyne receivers. The MICRF112’s maximum ASK data rate is 50kbps (Manchester Encoding). It operates with FSK receivers as well. The chip is designed to support narrow band FSK (Frequency Shift Modulation) by switching an external capacitor in parallel with the reference crystal. The MICRF112’s maximum FSK data rate is 10kbps. Complete UHF transmitter Frequency range 300MHz to 450MHz Data rates up to 50kbps ASK, 10kbps FSK Output Power to 10dBm Low external part count Low standby current <1µA Low voltage operation (down to 1.8V) Operate with crystals or ceramic resonators Applications Remote Keyless Entry Systems (RKE) Remote Control (STB, HVAC and Appliances) Garage Door Opener Transmitters Remote Sensor Data Links Infrared Transmitter Replacement Tire Pressure Monitor System (TPMS) Ordering Information Part Number MICRF112YMM10 Temp. Range –40°C to +125°C Package 10-Pin MSOP QwikRadio is a registered trademark of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com December 2011 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Typical Application Figure 1. MICRF112 ASK Key Fob Design Note: Values in parenthesis are for 315MHz December 2011 2 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Pin Configuration ASK 1 10 VDD XTLIN 2 9 PAOUT XTLOUT 3 8 VSSPA VSS 4 7 EN XTAL_MOD 5 6 FSK 10-Pin MSOP (M) Pin Description Pin Number MSOP-10 Pin Name 1 ASK ASK DATA Input 2 XLIN Reference oscillator input connection. 3 XTLOUT Pin Function Reference oscillator output connection. 4 VSS 5 XTAL_MOD Ground 6 FSK FSK Data Input 7 EN Chip enable, active high Reference oscillation modulation port for FSK operation. 8 VSSPA PA Ground 9 PA_OUT PA output 10 VDD December 2011 Positive Power Supply 3 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage VDD ...................................................+5.0V Voltage on PAOUT......................................................+7.2V Voltage on I/O Pins ............................ VSS–0.3 to VDD+0.3 Storage Temperature Range ....................-65°C to + 150°C Lead Temperature (soldering, 10 seconds) ............ + 300°C ESD Rating.................................................................Note 3 Supply Voltage VDD ........................................ 1.8V to 3.6V Ambient Operating Temperature (TA) ...... –40°C to +125°C Programmable Transmitter Frequency Range: ....................................................... 300MHz to 450MHz Electrical Characteristics(Note 4) Specifications apply for VDD = 3.0V, TA = 25°C, FreqREFOSC = 13.560MHz, EN = VDD. Bold values indicate –40°C to 125°C unless otherwise noted. 1kbps data rate 50% duty cycle. RL 50ohm load (matched) Parameter Condition Min Typ Max Units 1µA µA Power Supply Standby supply current, Iq EN = VSS .05 Mark Supply Current ION @ 315MHz, POUT = +10dBm 11.2 @ 433.92MHz, POUT = +10dBm 11.2 mA @ 315MHz 2.7 mA @ 433.92 MHz 2.7 mA @315MHz, Note 4 10.5 dBm @433.92MHz, Note 4 10.5 dBm -39 dBc -53 dBc -55 dBc -55 dBc 70 dBc SPACE supply current, IOFF mA RF Output Section and Modulation Limits: Output power level, POUT FSK or ASK "mark" Harmonics output for 315 MHz Harmonics output for 433.92 MHz @ 630MHz, @945MHz, Note 4 Note 4 2nd harm. 3rd harm. @ 867.84MHz, Note 4 2nd harm. @1301.76MHz, Note 4 3rd harm. Extinction ratio for ASK FSK Modulation Frequency Deviation load capacitor = 10pF, crystal type = HC49/U 22 Data Rate kHz 10 kbps 50 kbps ASK Modulation Data Rate Occupied Bandwidth @315MHz, Note 6 <700 kHz @433.92MHz, Note 6 <1000 kHz -76 dBc/Hz VCO Section 315 MHz Single Side Band Phase Noise 433.92 MHz Single Side Band Phase Noise @ 100kHz from Carrier @ 1000kHz from Carrier -79 dBc/Hz @ 100kHz from Carrier -72 dBc/Hz @ 1000kHz from Carrier -81 dBc/Hz 2 pF Reference Oscillator Section XTLIN, XTLOUT, XTLMOD Pin capacitance External Capacitance See Schematic C17 & C18 18 pF Oscillator Startup Time Note 5 Crystal: HC49S 300 µs STDBY transition from LOW to HIGH 500 µs Digital / Control Section Output Blanking December 2011 4 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Electrical Characteristics (cont.) Parameter Condition Min Digital Input (EN, ASK and FSK) High (VIH) 0.8×VDD Low (VIL) Digital Input Leakage Current (EN, ASK and FSK Pins) Typ Max Units 0.2×VDD V V High (VIH) 0.05 µA Low (VIL) 0.05 µA 1.6 V Under Voltage Lock Out (UVLO) 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. Measured using Test Circuit in Figure 2. Note 5. Dependent on crystal Note 6. RBW = 100kHz, OBW measured at -20dBc. December 2011 5 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Test Circuit Figure 2. MICRF112 Test Circuit with 50Ω Output Note 1. Values without parenthesis are for 433.92 MHz and values in parenthesis are for 315MHz Note 2. C9 = 100pF for external REF-OSC Note 3. For FSK R1 = 0Ω, R2 = NP, R6 = 100k, and R5 = NP December 2011 6 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Assembly Drawing Top Layer MICRF112 50 Ohm Test Board MICRF112 50 Ohm Test Board Bottom Layer MICRF112 50 Ohm Test Board December 2011 7 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Typical Characteristics Using MICRF112, 50Ω test Board 315MHz OBW, ASK = 1kHz 315Mhz OBW, ASK = 50kHz CW Max Power @ 3V, 315MHz, ASK = 1kHz, Note 1 RF Spectrum 2nd Harmonic; Fundamental at 315 MHz RF Spectrum 3rd Harmonic; Fundamental at 315 MHz 315MHz, Power Level at Space, VDD = 3.0V, ASK = 1kHz Note 1. 1.2dB cable loss. December 2011 8 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 315MHz, Zero Span , ASK = 1kHz 315MHz, Zero Span, ASK = 50kHz 315MHz, Phase Noise, ASK = 1kHz, 100kHz Offset, –75.59dBc/Hz 315MHz, Phase Noise, ASK = 1khz, 1MHz Offset, –78.99dBc/Hz 315MHz, Phase Noise, ASK = CW, 100kHz Offset, –74.39dBc/Hz 315MHz, Phase Noise, ASK = CW, 1MHz Offset, –77.28dBc/Hz December 2011 9 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 433.92MHz OBW, ASK = 1kHz 433.92MHz OBW, ASK = 50kHz 433.92MHz, CW Max Power @ 3V, ASK = 1kHz, Note 1 RF Spectrum 2nd Harmonic; Fundamental at 433.92 MHz RF Spectrum 3rd Harmonic; Fundamental at 433.92 MHz 433.92MHz Power Level at Space, VDD = 3.0V, ASK = 1kHz Note 1. 1.3dB cable loss. December 2011 10 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 433.92MHz Zero Span, 1kHz 433.92ASK Zero Span at 50kHz 433.92MHz Phase Noise, ASK = CW, 100kHz Offset, –81.04dBc/Hz 433.92MHz Phase Noise, ASK = CW, 1MHz Offset, –78.76dBc/Hz 433.92MHz Phase Noise, ASK = 1kHz, 100kHz Offset, –71.73dBc/Hz 433.92MHz Phase Noise, ASK = 1kHz, 1MHz Offset, –81.04dBc/Hz December 2011 11 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Functional Diagram Figure 3. Functional Block Diagram MICRF112 10 Pin ASK / FSK Version Functional Description Figure 3 shows a functional block diagram of the MICRF112 transmitter. The MICRF112 can be best described as a phase locked transmitter. The system can be partitioned into six functional blocks; crystal oscillator, PLL×32, power amplifier, enable control, under voltage detect and open drain switch for FSK operation. Crystal Oscillator The reference oscillator is crystal-based Pierce configuration. It is designed to accept crystals with frequency from 9.375MHz to 14.0625MHz. Figure 4. Reference Oscillator ASK Operation Crystal Oscillator Parameters for ASK Operation Figure 4 shows a reference oscillator circuit configuration for ASK operation. The reference oscillator is capable of driving crystals with ESR range from 20Ω to 300Ω. When the ESR of crystal is at 20Ω, the crystal parameter limits are: ESR 20Ω CPAR 2 to 10pF CMO 10 to 40fF December 2011 When the ESR of crystal is at 300Ω, the crystal parameter limits are: ESR 300Ω 2 to 5pF CPAR CMO 10 to 40fF CLOAD 10 to 30pF 12 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Power Amplifier The power amplifier serves two purposes: 1) to buffer the VCO from external elements and 2) to amplify the phase locked signal. The power amplifier can produce +10dBm at 3V (typical). Crystal Oscillator for FSK Operation Figure 5 shows reference oscillator circuit configuration for FSK operation. To operate the MICRF112 in FSK mode, one additional capacitor is needed between XTALOUT pin and XTALMOD pin. Crystal parameters for FSK operation are the same as ASK operation except: When the ESR of crystal is at 20Ω, CFSK + CLOAD not to exceed 70pF. When the ESR of crystal is at 300Ω, CFSK + CLOAD not to exceed 30pF Enable Control Enable control gates the ASK data. It only allows transmission when Lock, Amplitude and Under Voltage Detect conditions are valid. Under Voltage Detect “Under voltage detect” block senses operating voltage. If the operating voltage falls below 1.6V, “under voltage detect” block will send a signal to “enable control” block to disable the PA. Open Drain Switch Open drain switch is used for FSK operation. FSK data is fed into the FSK pin. The FSK pin is connected to the gate of the open drain switch. The open collector is connected to the XTALMOD pin. In Figure 4, a capacitor is shown connected from XTALMOD pin to XTALOUT. When FSK pin goes high, the capacitor between XTALMOD and XTALOUT pulls the frequency of REFOSC low . Figure 5. Reference Oscillator FSK Operation PLL ×32 The function of PLL×32 is to provide a stable carrier frequency for transmission. It is a “divided by 32” phase locked oscillator. December 2011 13 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Application Information Figure 6. ASK 433.92MHz and 315MHz Note: Values in parenthesis are for 315MHz The MICRF112 is well suited to drive a 50 ohms source, monopole or a loop antenna. Figure 6 is an example of a loop antenna configuration. Figure 6 also shows both 315MHz and 433.92MHz ASK configurations for a loop antenna. Besides using a different crystal, Table 1 lists modified values needed for the listed frequencies. Frequency (MHz) L1 (nH) C5 (pF) L4 (nH) C7 (p Y1 (MHz) R7, Ω Output Power, dBm IDD, mA 0 10 6.7 75 8.5 6.3 100 8.0 6.2 500 1.6 4.13 1000 -3.8 4.87 Output Power Versus External Resistor at 315MHz F) 315.0 470 10 150 6.8 9.84375 433.92 680 10 82 4.7 13.5600 Table 1 The reference design shown in Figure 6 has an antenna optimized for using the matching network as described in Table 1. Power Control Using External Resistor R7 is used to adjust the RF output levels which may be needed to meet compliance. As an example, the following tables list typical values of conducted RF output levels and corresponding R7 resistor values for the 50Ω test board shown in Figure 2. R7 of the TX112 Demo board using the loop antenna can be adjusted for the appropriate radiated field allowed by FCC or ETSI compliance. Contact Micrel for suggested values to meet FCC and ETSI compliances. December 2011 R7, Ω Output Power, dBm IDD, mA 0 8.68 7.5 75 8.34 7.33 100 8.02 7.3 500 4.34 6.3 1000 0.42 5.5 Output Power Versus External Resistor at 433.92 MHz 14 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 much as 10%. To reduce parasitic inductance, the use of wide traces and a ground plane under signal traces is recommended. Vias with low value inductance should be used for components requiring a connection-to-ground. Output Matching Network Part of the function of the output network is to attenuate the second and third harmonics. When matching to a transmit frequency, care must be taken not only to optimize for maximum output power but to attenuate unwanted harmonics. Layout Issues PCB Layout is of primary concern to achieve optimum performance and consistent manufacturing results. Care must used on orientation of components to ensure they do not couple or decouple the RF signal. PCB trace length should be short to minimize parasitic inductance, (1 inch ~ 20nH). For example, depending on inductance values, a 0.5 inch trace can change the inductance by as December 2011 Antenna Layout Directivity is affected by antenna trace layout. No ground plane should be under the antenna trace. For consistent performance, components should not be placed inside the loop of the antenna. Gerbers for Figure 7, with a suggested layout, can be obtained on the Micrel web site at: http://www.micrel.com. 15 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 PCB Board Assembly Drawing Top Layer MICRF112 Demo Board MICRF112 Demo Board Bottom Layer MICRF112 Demo Board Figure 7. Demo Board PCB December 2011 16 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Figure 8. TX112-1 Demo Board Schematic Note: Configuration is for ASK operation. Values in parenthesis are for 315MHz December 2011 17 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 components labeled as NP are to obtain different configurations including FSK Mode of operation. Table 2 describes each header pin connector used in the demo board. Functional Description of TX112-1 Evaluation Board. Figure 7 shows the TX112-1 Demo Board PCB. Figure 8 is a detailed schematic of the TX112-1. Note that Pin Function Name Functional Description J1-1 VDD 1.8V to 3.6V J1-2 Ground VSS J1-3 ASK INPUT Modulating Data Input, ASK or FSK J2-1 REF-OSC External Reference Input J2-2 GROUND VSS J2-3 ENABLE Enable Input, Active High TX112-1-433.92 ASK Bill of Materials PCB Footprint 0805 0603 0603 Item 1 2 3 4 5 6 7 8 9 10 11 Quantity 1 1 1 3 5 1 1 2 2 1 1 Ref C1 C2 C5 R1,R4,R6 C6,C8,C11,C12,C15 C7 C10 C13,C14 J1,J2 L1 L4 Part 10µF 100pF 10pF (np) (np) 4.7pF 0.1µF 18pF CON3 680nH 82nH 12 13 1 1 ANTENNA 100kΩ 14 13 14 6 1 1 L5 R2 R3,R5,R7 R8,JPR1,JPR2 U1 Y1 0603 0603 0603 0805 0603 0603 0Ω MICRF112YMM10 13.560MHZ XTAL 0603 Mfg P/N GRM21BR60J106KE01L GRM1885C1H101JA01D GRM1885C1H100JA01D Manufacturer muRata muRata muRata GRM1885C1H4R7JA01D GRM188F51H104ZA01D GRM1885C1H180JA01D TSHR-114-S-02-A-GT 0805CS-680XJB 0603CS-082NXJB ANTENNA LOOP, Part of PCB CRCW0603100KFKEA muRata muRata muRata CRC06030000Z0EA MICRF112YM SA-13.5600-F-10-C-3-3 Coilcraft Coilcraft Vishay Vishay Micrel HIB Table 2 December 2011 18 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Tx112-1-315MHz ASK Bill of Materials PCB Footprint 0805 0603 0603 Item 1 2 3 4 5 6 7 8 9 10 11 Quantity 1 1 1 3 5 1 1 2 2 1 1 Ref C1 C2 C5 R1,R4,R6 C6,C8,C11,C12,C15 C7 C10 C13,C14 J1,J2 L1 L4 Part 10µF 100pF 10pF (np) (np) 4.7pF 0.1µF 18pF CON3 470nH 150nH 12 13 1 1 ANTENNA 100kΩ 14 13 6 1 L5 R2 R3,R5,R7 R8,JPR1,JPR2 U1 14 1 Y1 0603 0603 0603 0805 0603 0Ω MICRF112YMM10 9.84375MHZ XTAL 0603 Mfg P/N GRM21BR60J106KE01L GRM1885C1H101JA01D GRM1885C1H1000JA01D Manufacturer muRata muRata muRata GRM1885C1H6R8JA01D GRM188F51H104ZA01D GRM1885C1H180JA01D TSHR-114-S-02-A-GT 0805CS-470XJB 0603CS-R15XJB ANTENNA LOOP, Part of PCB CRCW0603100KFKEA muRata muRata muRata 0603 Coilcraft Coilcraft Vishay CRC06030000Z0EA MICRF112YM Vishay Micrel SA-9.84375-F-10-C-3-3 HIB Table 3 FSK Operation Table 2 and 3 describe the ASK operation for 433.92MHz and 315MHz. Table 4 lists the component values that change between ASK or FSK operation. Please note that use of a high FSK data rate may excite parasitic resonant modes with some crystal types. Recommended crystals from Table 2 and 3 are good for both ASK and FSK. Mode R1 R2 R5 R6 JPR1 JPR2 C8 ASK NP 100kΩ 0Ω NP 0Ω NP NP FSK 0Ω NP NP 100kΩ NP 0Ω (1)3.3pF (2)10pF Notes: 1. C8 = 3.3pF for 1kHz using HC49/U or HC49US type crystals. 2. C8= 10pF for 10kHz using HC49/U, (high profile) only. Table 4: ASK and FSK Settings R3 R4 Constant ON 0Ω NP External Standby Control NP 100kΩ Table 5: Enable Control (Shutdown) December 2011 19 M9999-120911 (408) 944-0800 Micrel, Inc. MICRF112 Package Information 10-Pin MSOP Package Type (YMM10) 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 believed to be accurate and reliable. However, no responsibility is assumed 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 authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended 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 significant 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. © 2011 Micrel, Incorporated. December 2011 20 M9999-120911 (408) 944-0800