MAX7042 Evaluation Kit Evaluates: MAX7042 General Description The MAX7042 evaluation kit (EV kit) allows for a detailed evaluation of the MAX7042 superheterodyne receiver. It enables testing of the device’s RF performance and requires no additional support circuitry. The RF input circuit is designed to work with a 50I source impedance RF signal generator and has an SMA connector for convenient connection to test equipment. The EV kit can also directly interface to the user’s embedded design for easy data decoding. The MAX7042 EV kit comes in two versions, a 315MHz version and a 433.92MHz version. The passive components are optimized for these frequencies. These components can be changed to work at 308MHz and 418MHz. In addition, the 4kbps Manchester received data rate can be adjusted from 0kbps to 33kbps by changing two more components. For easy implementation into the customer’s design, the MAX7042 EV kit also features a proven PCB layout that can be duplicated easily for quicker time to market. The EV kit Gerber files are available upon request. Features S Proven PCB Layout S Proven Components Parts List S Multiple Test Points Provided On Board S Available in 315MHz or 433.92MHz Optimized Versions S 308MHz and 418MHz Operation Possible by Changing Components S Fully Assembled and Tested S Can Operate as a Stand-Alone Receiver with the Addition of an Antenna Ordering Information PART TYPE MAX7042EVKIT-315+ EV Kit MAX7042EVKIT-433+ EV Kit +Denotes lead(Pb)-free and RoHS compliant. Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION C1, C20, C21 3 0.01FF Q10%, 50V X7R ceramic capacitors (0603) Murata GRM188R71H103K C11, C18 2 220pF Q10%, 50V C0G ceramic capacitors (0603) Murata GRM1885C1H221K C2, C22 2 0.1FF Q10%, 16V X7R ceramic capacitors (0603) Murata GRM188R71C104K C12 1 1500pF Q10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H152K C3, C4 2 15pF Q5%, 50V C0G ceramic capacitors (0603) Murata GRM1885C1H150J C14, C15, C16 3 0.047FF Q10% 50V X7R ceramic capacitors (0603) Murata GRM188R71H473K C5, C6, C13, C19 0 Not installed, ceramic capacitors (0603) C17 1 C7, C8, C9 3 100pF Q5%, 50V C0G ceramic capacitors (0603) Murata GRM1885C1H101J 470pF Q5% 50V C0G ceramic capacitor (0603) Murata GRM1885C1H471JA01 C10 1 315MHz: 1.2pF Q0.1pF, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H1R2B 433.92MHz: Not installed, ceramic capacitor (0603) GND, TP8 2 Black miniature test points JU1, JU4–JU11 9 3-pin headers JU2, JU3 0 Not installed, 3-pin headers JU12 1 2-pin header L1 1 315MHz: 82nH Q5% inductor (0603) Coilcraft 0603CS-82NXJLU 433.92MHz: 39nH Q 5% inductor (0603) Coilcraft 0603CS-39NXJLU For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-4963; Rev 0; 9/09 MAX7042 Evaluation Kit Evaluates: MAX7042 Component List (continued) DESIGNATION QTY L2 1 DESCRIPTION DESIGNATION QTY 315MHz: 3.9nH Q5% inductor (0603) Coilcraft 0603CS-3N9XJLU 8 Red miniature test points U1 1 Low-power, FSK superheterodyne receiver (32 TQFN-EP*) Maxim MAX7042ATJ+ 433.92MHz: 0I Q5% resistor (0603) L3 1 R1, R5 0 R2, R3, R4 DESCRIPTION TP1–TP7, VDD 315MHz: 30nH Q5% inductor (0603) Murata LQW18AN30NJ00 315MHz: 9.509375MHz crystal Crystek 017034 Y1 1 Not installed, resistors (0603) Y2 1 10.7MHz ceramic filter TOKO #SK107M1N-AO-10 433.92MHz: 16nH Q5% inductor (0603) Murata LQW18AN16NJ00 433.92MHz: 13.2256MHz crystal Crystek 017035 3 100kI Q5% resistors — 9 Shunts REF_IN, MIXOUT 0 Not installed, SMA female verticalmount connectors — 1 PCB: MAX7042 EVALUATION KIT+ RF_IN 1 *EP = Exposed pad. SMA female vertical-mount connector Component Suppliers SUPPLIER PHONE WEBSITE Coilcraft, Inc. 847-639-6400 www.coilcraft.com Crystek Corporation 800-237-3061 www.crystek.com Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com TOKO America, Inc. 847-297-0070 www.tokoam.com Note: Indicate that you are using the MAX7042 when contacting these component suppliers. Quick Start Required Equipment • MAX7042 EV kit • Regulated power supply capable of providing 3.3V • RF signal generator capable of delivering -120dBm to 0dBm output power at the operating frequency, in addition to frequency modulation (FM) capabilities (Agilent E4420B or equivalent) • Optional ammeter for measuring supply current • Oscilloscope Procedure The MAX7042 EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the DC power supply or RF signal generator until all connections are completed. 2 1) Verify that the jumpers are in their default position, as shown in Table 1. 2) Connect a DC supply set to 3.3V (through an ammeter, if desired) to the VDD and GND terminals on the EV kit. Do not turn on the power supply. 3) Connect the RF signal generator to the RF_IN SMA connector. Do not turn on the generator output. Set the generator for an output carrier frequency of 315MHz (or 433.92MHz) at a power level of -100dBm. Set the modulation of the generator to provide a FSK signal with ±50kHz frequency deviation modulated with a 4kHz square wave. 4) Connect the oscilloscope to test point TP6 (DS+ or data slicer positive input). Set the oscilloscope to AC-coupling and set the vertical scale to approximately 100mV/div. Maxim Integrated MAX7042 Evaluation Kit Evaluates: MAX7042 5) Turn on the DC supply. The supply current should read approximately 7.2mA for an EV kit that is set for maximum sensitivity (JU4 pins 1-2 connected). To draw slightly less current, with slightly less sensitivity, connect JU4 pins 2-3. 6) Remove the shunt from JU7 momentarily and restore it to the 1-2 position. JU7 is the enable input and toggling it once ensures that the FSK demodulator is calibrated and operational. 7) Activate the RF generator’s output with modulation and observe TP6 on the scope. Use the RF generator’s LF OUTPUT (modulation output) to trigger the oscilloscope. The scope should show a 200mV to 250mV peak-to-peak, lowpass-filtered square wave. If the RF power is turned off, the scope trace shows a noise voltage with high-amplitude and high-frequency characteristics. These are the clicks that characterize the response of an FM demodulator to noise. To estimate the sensitivity, reduce the RF power to a level where the square wave on the scope is noisy but recognizable. This power level should be below -107dBm. In some cases, the sensitivity can be improved by removing the ammeter. 8) Move the scope probe to TP3 (DATA), change the coupling on the scope back to DC, and set the vertical scale to 1V/div or 2V/div. A 4kHz square wave going from ground to VDD (3.3V in this case) should be seen. As the RF power is increased, this square wave becomes cleaner. Another way to estimate sensitivity from this test point is to reduce the RF power until the square wave becomes extremely asymmetric (duty cycle not 50%) and contains shortdata transitions (glitches) in the middle of a data interval. This power level should be below -107dBm, similar to the level seen in the previous step. Layout Issues A properly designed PCB is essential for any RF/microwave circuit. Keep high-frequency input and output lines as short as possible to minimize losses and radiation. At high frequencies, trace lengths that are on the order of λ/10 or longer can act as antennas. Table 1. Jumper Table JUMPER SHUNT POSITION DESCRIPTION 1-2* Connects AVDD to VDD3 2-3 Connects AVDD to TP1 JU2 — Not populated, leave open JU3 — Not populated, leave open JU1 JU4 1-2* Selects high sensitivity 2-3 Selects normal sensitivity JU8 JU9 Connects FSEL2 to VDD (default for 433.92MHz); see Table 2. JU10 2-3 Connects FSEL2 to GND (default for 315MHz); see Table 2. JU11 1-2* Connects FSEL1 to VDD; see Table 2 2-3 Connects FSEL1 to GND; see Table 2 JU6 SHUNT POSITION JU7 1-2 JU5 Maxim Integrated JUMPER 1-2* Turns on the MAX7042 2-3 Puts the MAX7042 in shutdown 1-2* Connects HVIN to VDD 2-3 Connects HVIN to TP4 1-2* Connects DVDD to VDD3 2-3 Connects DVDD to TP5 1-2* No peak-detector operation 2-3 Use peak detector for faster receiver startup 1-2 Mixer output to MIXOUT 2-3 External IF input Open* JU12 DESCRIPTION 1-2* Open Normal operation, leave open Connects VDD to +3.3V supply Connects VDD to +5V supply *Default position. 3 MAX7042 Evaluation Kit Evaluates: MAX7042 Both parasitic inductance and capacitance are influential on circuit layouts and are best avoided by using short trace lengths. Generally, a 10-mil wide PCB trace, 0.0625in above a ground plane, with FR4 dielectric has approximately 19nH/in of inductance and approximately 1pF/in of capacitance. In the LNA output/mixer input tank circuit, the proximity to the MAX7042 IC has a strong influence on the effective component values. To reduce the parasitic inductance, use a solid ground or power plane below the signal traces. Also, use lowinductance connections to ground on all GND pins, and place decoupling capacitors close to all VDD connections. The MAX7042 EV kit PCB can serve as a reference design for laying out a board using the MAX7042. Detailed Description of Hardware Power Supply The MAX7042 can operate from 3.3V or 5V supplies. For 5V operation, remove jumper JU12 before connecting the supply to VDD. AVDD is the output of an internal regulator when VDD = 5V. AVDD and DVDD are connected on the EV kit through VDD3. For 3.3V operation, connect JU12. IF Input/Output The 10.7MHz IF can be monitored with an oscilloscope or a spectrum analyzer. To monitor the IF output with an oscilloscope, connect the scope probe to pin 3 of JU11. Increase the RF signal generator power to approximately -70dBm and set the scope amplitude to 20mV or 50mV per division. Set the time per division on the horizontal trace to 100ns. The scope trace shows the waveform at the output of the external ceramic IF filter. To monitor the IF output on a spectrum analyzer, use the high-impedance probe attachment from the spectrum analyzer, if one is available, and connect it to pin 3 of JU11. Table 2. Frequency Selection Table FSEL2 (JU5) There is a MIXOUT location on the board that can be populated with a board-mounted SMA connector to monitor the IF output or to inject an IF signal into the IFIN+ pin. Remove the ceramic filter (Y2) for such a measurement and include R1 (270I) and C13 (0.01µF) to match the 330I mixer output with the 50I spectrum analyzer. Connect pins 1-2 of jumper JU11 to see the IF output on the spectrum analyzer. Connect pins 2-3 of jumper JU11 to inject an IF signal into the IFIN+ pin from an external source. REF_IN External Frequency Input For applications where the correct frequency crystal is not available, it is possible to directly inject an external frequency through the REF_IN SMA connector. Connect the SMA to a function generator. The addition of C5 and C6 (use 0.01µF capacitors), plus the removal of C3 and C4 are necessary. The recommended amplitude of the function generator is 500mVP-P. Test Points and I/O Connections Additional test points and I/O connectors are provided to monitor the various baseband signals and for external connections. See Tables 3 and 4 for a description. Table 3. Test Points TEST POINT DESCRIPTION 1 AVDD 2 RSSI 3 FSK data out 4 HVIN 5 DVDD 6 Positive input to data slicer 7 Negative input to data slicer Table 4. I/O Connectors TEST POINT DESCRIPTION RF_IN RF input REF_IN External reference frequency input IF input/output FSEL1 (JU6) FREQUENCY (MHz) MIXOUT 0 0 308 GND Ground 0 1 315 VDD Supply input 1 0 418 1 1 433.92 Note: 1 = 1-2 position; 0 = 2-3 position. 4 Maxim Integrated MAX7042 Evaluation Kit Evaluates: MAX7042 Figure 1. MAX7042 EV Kit Schematic Maxim Integrated 5 MAX7042 Evaluation Kit Evaluates: MAX7042 Figure 2. MAX7042 EV Kit Component Placement Guide— Component Side Figure 3. MAX7042 EV Kit PCB Layout—Component Side Figure 4. MAX7042 EV Kit PCB Layout—Solder Side 6 Maxim Integrated MAX7042 Evaluation Kit Evaluates: MAX7042 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 © 2009 Maxim Integrated Products, Inc. 7 Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.