9-76; Rev 0; 5/05 General Description The MAX479 evaluation kit (EV kit) allows for a detailed evaluation of the MAX479 ASK/FSK transmitter. It enables testing of the device s RF performance and requires no additional support circuitry. The RF output uses a 50Ω matching network and an SMA connector for convenient connection to test equipment. A reverse polarity SMA is also included to connect to a /4 wave whip antenna. The EV kit can also directly interface to the user s embedded design for easy data encoding. The MAX479EV kit comes in two versions: a 5MHz version and a 4.9MHz version. The passive components are optimized for these frequencies. These components can easily be changed to work at RF frequencies from 00MHz to 450MHz. For easy implementation into the customer s design, the MAX479EV kit also features a proven PC board layout, which can be easily duplicated for quicker time-tomarket. The EV kit Gerber files are available for download at www.maxim-ic.com. Features Proven PC Board Layout Proven Components Parts List Multiple Test Points Provided on Board Available in 5MHz or 4.9MHz Optimized Versions Adjustable Frequency Range from 00MHz to 450MHz* Fully Assembled and Tested Can Operate as a Stand-Alone Transmitter with Included Battery *Requires component changes. Ordering Information PART TEMP RANGE IC PACKAGE MAX479EVKIT-5-40 C to +85 C 6 Thin QFN MAX479EVKIT-4-40 C to +85 C 6 Thin QFN Component List C, C6 (5MHz) 5pF ±5%, 50V ceramic capacitors Murata GRM885CH50J C7, C9 0.47µF +80/-0%, 6V ceramic capacitors Y5V Murata GRM88F5C474Z C, C6 (4MHz) 6.8pF ±0.5pF, 50V ceramic capacitors C0G Murata GRM885CH6R8D C8, C, C 0pF ±5%, 50V ceramic capacitors Murata GRM885CHJ C (5MHz) pf ±5%, 50V ceramic capacitor C0G Murata GRM885CH0J C (5MHz).pF ±0.5pF, 50V ceramic capacitor C0G Murata GRM885CHRD C (4MHz) 0pF ±5%, 50V ceramic capacitor C0G Murata GRM885CH00J C (4MHz).0pF ±0.5pF, 50V ceramic capacitor C0G Murata GRM885CHR0D C, C0 0.0µF ±0%, 50V ceramic capacitors Murata GRM88R7H0KA0 C4, C5 00pF ±5%, 50V ceramic capacitors Murata GRM885CH0J C4 C5, C6, C8, C9 680pF ±5%, 50V ceramic capacitor C0G Murata GRM885CH68J 0 Not installed JU JU0 0 L (5MHz) L (4MHz) -pin headers Digi-Key S0-6-ND or equivalent 7nH ±5% inductor Coilcraft 060CS-7NXJB nh ±5% inductor Coilcraft 060CS-NXJB Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at -888-69-464, or visit Maxim s website at www.maxim-ic.com.
L (5MHz) L (4MHz) R nh ±5% inductor Coilcraft 060CS-NXJB 8nH ±5% inductor Coilcraft 060CS-8NXJB 5kΩ potentiometer BC Components SM4W50 R 0 0Ω resistor, any, not installed R 5.Ω ±5% resistor, any R4 0Ω resistor, any Antenna (5MHz) Antenna (4MHz) 0 AN TE N N A_OU T BAT Battery 5MHz /4-wave whip antenna, not provided Lynx ANT-5-CW-RH 4MHz /4-wave whip antenna, not provided Lynx ANT-4-CW-RH RP-SMA connector Linx CONREVSMA00 Battery holder MPD BA0 Coin-cell battery Panasonic BR0 REF_IN RF_OUT Component List (continued) SMA connector top mount, not installed Digi-Key J500-ND Johnson 4-070-0 SMA connector top mount Digi-Key J500-ND Johnson 4-070-0 U MAX479ATE, VSS, ENABLE, DATA_IN, CKOUT 5 Y (5MHz) Y (4MHz) Test points Mouser 5-0 or equivalent Crystal 9.8475MHz Hong Kong Crystal SSL984750E0FAFZ800 or Crystek 07000 Crystal.56MHz Hong Kong Crystal SSM56000E0FAFZ800 or Crystek 0700 0 Shunt (JU) Digi-Key S9000-ND or equivalent MAX479 EV kit PC board Component Suppliers SUPPLIER PHONE FAX Coilcraft 800--645 847-69-469 Crystek 800-7-06 94-56-05 Hong Kong Crystal 85-4-0 85-498-5908 Murata 800-8-97 84-8-0490 Note: Indicate you are using the MAX479 when contacting these manufacturers. Quick Start The following procedure allows for proper device evaluation. Required Test Equipment Regulated power supply capable of providing +.0V Spectrum analyzer such as the Agilent 856E Optional ammeter for measuring supply current Power meter such as the Agilent EPM-44A Connections and Setup This section provides a step-by-step guide to operating the EV kit and testing the device s functionality. Do not turn on the DC power until all connections are made: ) Connect a DC supply set to +.0V, through an ammeter, to the and VSS terminals on the EV kit. Do not turn on the supply. ) Connect the RF_OUT SMA connector to the spectrum analyzer. Set the analyzer to a center frequency of 5MHz (or 4.9MHz) and a span of MHz. ) Turn on the DC supply. The spectrum analyzer should display a peak of about +0dBm at 5MHz (or 4.9MHz). 4) Disconnect the spectrum analyzer and connect the power meter instead. Measure the output power and also the current draw. 5) Calculate the efficiency. This is done using the following equation: Efficiency = 0ˆ(P OUT /0)/(V x I) For example, for a +0.8dBm output, and a 0.9mA (at.0v) current, the efficiency is 7%.
Layout Issues A properly designed PC board is an essential part of any RF/microwave circuit. On high-frequency inputs and outputs, use controlled-impedance lines and keep them as short as possible to minimize losses and radiation. At high frequencies, trace lengths that are on the order of λ/0 or longer can act as antennas. Keeping the traces short also reduces parasitic inductance. Generally, in of a PC board trace adds about 0nH of parasitic inductance. The parasitic inductance can have a dramatic effect on the effective inductance. For example, a 0.5in trace connecting a 00nH inductor adds an extra 0nH of inductance or 0%. To reduce the parasitic inductance, use wider traces and a solid ground or power plane below the signal traces. Also, use low-inductance connections to ground on all GND pins, and place decoupling capacitors close to all connections. The EV kit PC board can serve as a reference design for laying out a board using the MAX479. Detailed Description Power-Down Control The MAX479 can be controlled externally using the ENABLE connector. The IC draws approximately 0.nA (at room temperature) in shutdown mode. Jumper JU is used to control this mode. The shunt can be placed between pins and to enable the device. Remove the JU shunt for external control. See Table for jumper function descriptions. Table. JU Through JU4 Jumpers Function JUMPER STATE FUNCTION JU JU JU JU4 - RF carrier transmit enable - Power-down mode N.C. External power-down control - - N.C. RF carrier transmit mode (ASK), FSK high frequency (FSK) PA off, PLL ON (ASK), FSK low frequency (FSK) External data transmit - External supply operation - Battery operation - FSK mode - ASK mode Data Input The MAX479 EV kit transmits ASK and FSK data with data rates of up to 00kbps (ASK) or 0kbps (FSK). JU controls whether the MAX479 transmits the ASK carrier frequency (or the FSK high frequency), turns off the PA (or transmits the FSK low frequency), or transmits an external data stream. See Table. 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 (not provided). Connect the SMA to a low-phase-noise generator. The addition of C8 and C9 is necessary (use 0.0µF capacitors). Battery Operation The MAX479 EV kit can be powered by an external power supply or by the supplied V coin-cell battery. Set jumper JU to connect pins and for battery operation. RF Output The MAX479 EV kit includes two SMA connectors for RF output. RF_OUT is a standard SMA and is used to connect the PA output to test equipment. Output is matched to 50Ω. ANTENNA_OUT is a reverse polarity SMA and is used to connect to the /4-wave whip antenna (not supplied). Note that resistor R (0Ω) needs to be added. Modulation Mode Input Jumper JU4 sets the mode of transmission. Set jumper JU4 to connect pins and for FSK mode, and for ASK mode. FSK Frequency Deviation The FSK deviation is set by jumpers JU5 through JU7. The maximum deviation depends on the PC board parasitics. The EV kit max is around 50kHz (5MHz). If very large FSK frequency deviations are desired, use a crystal with a larger motional capacitance and/or reduce PC board parasitic capacitances. One way to reduce parasitic capacitances on the EV kit is to remove C4, C5, and C6 and move the crystal closer to the IC.
Table. Clock-Divider Settings JUMPER SETTING JUMPER SETTING JUMPER SETTING FUNCTION JU5 - - - Max deviation - - - 7/8 x max deviation - - - /4 x max deviation - - - 5/8 x max deviation JU6 JU7 - - - / x max deviation - - - /8 x max deviation - - - /4 x max deviation - Clock Output Jumpers JU8 and JU9 set the divider ratio for the clock output. See Table for the settings. Table. Clock Divider Settings Envelope Shaping Jumper JU0 sets envelope shaping for a more gentle turn-on/turn-off of the PA in ASK mode. Set jumper JU0 to connect pins and to allow for envelope shaping. See Table 4 for settings. - JUMPER SETTING JUMPER SETTING FUNCTION JU8 - - f XTAL /6 - - f XTAL /8 - JU9 - f XTAL /4 - - Table 4. JU0 Jumper Function JUMPER STATE FUNCTION - No envelope shaping JU0 - Envelope shaping Logic 0 output - /8 x max deviation I/O Connections Table 5 is a list of all I/O connections. Table 5. I/O Connectors RF_OUT REF_IN SIGNAL ANTENNA_OUT VSS DATA_IN ENABLE CLKOUT RF output External reference frequency input Reverse polarity SMA for /4-wave antenna Ground Power-supply input Data input Power-down control Buffered clock output For additional information and a list of application notes, consult the www.maxim-ic.com website. 4
DATA_IN ENABLE C8 JU4 JU JU 4 4 XTAL MODE DIN ENABLE C4 00pF Y* C6 U MAX479 C5 00pF XTAL GND V DD _PA ROUT 5 6 6 7 C9 C5 R 5kΩ REF_IN VSS C7 0.47µF JU0 L* C 0pF C9 0.47µF 50Ω OUTPUT * AT 5MHz AT 4.9MHz C 5pF 6.8pF C pf 0pF C6 5pF 6.8pF C.pF.0pF L 7nH nh L nh 8nH Y 9.8475MHz.56MHz USE WIRE-WOUND INDUCTORS ONLY. C0 0.0µF C8 0pF C 0pF C 0.0µF C4 680pF R 5.Ω R4 0Ω JU BAT CKOUT 5 CLKOUT PAOUT CLK0 CLK DEV0 DEV DEV 9 0 JU9 JU7 JU5 8 C* C* C* L* C6* RF_OUT R ANTENNA_OUT JU8 JU6 Figure. MAX479 EV Kit Schematic 5
Figure. MAX479 EV Kit Component Placement Guide Component Side Figure. MAX479 EV Kit PC Board Layout Component Side Figure 4. MAX479 EV Kit PC Board Layout Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 6 Maxim Integrated Products, 0 San Gabriel Drive, Sunnyvale, CA 94086 408-77-7600 005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.