19-1398; Rev 2; 8/99 MAX3510 Evaluation Kit The MAX3510 evaluation kit (EV kit) simplifies evaluation of the MAX3510 CATV upstream amplifier. The kit includes a serial data interface, which can be programmed via the parallel port of a standard PC. Software (DOS and Windows) is included to facilitate this function. This software allows the user to program both the gain and transmit modes through a simple user interface. Access to the device input and output is provided through 50Ω SMA connectors. The input is matched to 50Ω, while the output circuit contains a series 24Ω resistor that increases the load on the output transformer to 75Ω nominal when using 50Ω test equipment. Features ♦ Single +5V Operation ♦ Output Level Range from <8dBmV to 64dBmV ♦ Gain Programmable in 1dB Steps via Software ♦ Transmit-Disable Mode ♦ Two Shutdown Modes ♦ Control Software Included ♦ Fully Assembled and Tested Surface-Mount Board Ordering Information Component List DESIGNATION QTY PART MAX3510EVKIT DESCRIPTION B1, B2, L1–L3 5 Surface-mount bead cores Murata BLM11P 300SPT C1, C4, C6, C8, C9 5 0.1µF, 10% ceramic capacitors TEMP. RANGE IC PACKAGE -40°C to +85°C 20 SSOP Component Suppliers SUPPLIER PHONE FAX 803-946-0690 803-626-3123 C2, C3 2 0.001µF, 10% ceramic capacitors AVX 978-442-5000 978-442-4178 1 0.0033µF, 10% min, 10V ceramic capacitor M/A-COM C5 Murata 814-237-1431 814-238-0490 Toko 847-297-0076 847-297-7864 C7 1 10µF, ±10% capacitor AVX TAJB106K010 IN1, IN2 2 Test points J1, J3 2 SMA connectors (edge mount) J2 1 DB25 connector, right angle, female JU1–JU4 4 3-pin headers JU5–JU7 3 2-pin headers None 7 Shunts (for JU1–JU7) R1 1 49.9Ω, 1% resistor Note: Please indicate you are using the MAX3510 when contacting these suppliers. Quick Start R5 1 24Ω, 5% resistor R14, R15 2 100kΩ, 5% resistors The MAX3510 EV kit is fully assembled and factory tested. Follow the instructions in the Connections and Setup section. Note: The output circuit contains a series 24Ω resistor that is used to bring the load impedance up to 75Ω. This must be accounted for in all measurements (see Output Circuit section). Note: The input transformer is supplied to allow differential input drive from a single-ended source. No transformer is required in the application. T1 1 4:1 transformer (2:1 voltage ratio) Toko 458PT-1087 • T2 1 1:1 transformer M/A-COM ETC1-1T U1 1 MAX3510EEP None 1 MAX3510 data sheet None 1 MAX3510 PC board None 1 MAX3510 software disk None 1 MAX3510 EV kit data sheet R2–R4, R6–R13, R16, R17–R19 Not installed Test Equipment Required • • • DC supply capable of delivering 5.5V and 150mA of continuous current. HP8648 or equivalent signal source capable of generating 40dBmV up to 200MHz. HP8561E or equivalent spectrum analyzer with a minimum 200MHz frequency range. Digital multimeter (DMM) to monitor VCC and ICC, if desired. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. Evaluates: MAX3510 General Description Evaluates: MAX3510 MAX3510 Evaluation Kit • • • • • • • Lowpass filters to attenuate harmonic output of signal sources, if harmonic measurements are desired. Network analyzer, such as the HP8753D. (May be used to measure gain and harmonic levels if configured with this option; contact manufacturer.) IBM PC or compatible. Male-to-male 25-pin parallel cable, straight through. 0 to 5V pulse generator (transient measurement). Low-noise amplifier with 40dB gain from 5MHz to 100MHz (Noise Measurement). Oscilloscope with 200MHz bandwidth. Connections and Setup 1) Connect the +5V power supply to the pins labeled +5V and GND on the circuit board. Connect a 50Ω signal source to INPUT and terminate OUTPUT with a spectrum analyzer or network analyzer having a 50Ω input impedance. If using a signal source with a source impedance other than 50Ω, or if a different input impedance is required, be sure to replace resistor R1 with the appropriate value resistor. 2) Connect a 25-pin male-to-male cable between the parallel (printer) port of the PC and the 25-pin female connector on the EV kit board. Ensure that shunts are placed on jumpers JU5, JU6, and JU7. These shunts connect the appropriate pins of the DB25 connector to the serial data interface of the MAX3510. Also check that pins 2 and 3 of jumper JU3 and pins 1 and 2 of jumper JU1 are shunted. 3) Turn on the power supply. Turn on the PC and the test equipment. Set the signal source for -13dBm (34dBmV across a 50Ω load). 4) Run the software program. Detailed Description Using the Software The MAX3510 uses a serial data interface (SDI) to set gain and to control software-shutdown mode. Some means of communicating with the SDI is required to use the MAX3510 EV kit. A microprocessor, pattern generator, or PC can be used for this function. Software is included in this EV kit to facilitate the use of a PC. The disk included with the MAX3510 EV kit contains two programs. The first is a QuickBasic® program that runs under DOS and the second is an EXE file that requires Windows 95® to run. The disk contains two directories (Table 1). Table 1. MAX3510 EV Kit Software DIRECTORY FILE NAME DESCRIPTION DOS MAX3510.BAS QuickBasic Source Code DOS READ3510.TXT “Read Me” Text File Windows MAX3510.EXE Windows Executable Windows MAX3510.DLL DLL File for Printer Port Control Windows READWIN3510.TXT “Read Me” Text File If your PC has Windows 95 installed, read the file READWIN3510.TXT for instructions on operation of the MAX3510.EXE file. If your PC does not have Windows 95 installed, use the program MAX3510.BAS. Instructions for the QuickBasic program are found in READ3510.TXT. Gain Adjustment Valid gain states range from 0 to 63. The nominal change in gain is 1dB per gain state. Gain states are set exclusively by programming the SDI. See the MAX3510 data sheet for details. Shutdown and Transmit Enable Jumpers JU1 and JU3 determine how the shutdown and transmit-enable features are controlled. Pin 2 of each of these jumpers is connected directly to the device. If an external source (such as a modulator chip or microprocessor) is used to control these features, simply make the connection to pin 2 of the appropriate jumper. Pads are provided on the bottom side of the board (R18 and R19, respectively) for placement of termination resistors, if needed. If manual control of shutdown and transmit-enable is desired, shunt pins 2 and 3 of jumper JU1 and pins 1 and 2 of jumper JU3. This will allow SHDN and TXEN to be controlled by JU2 and JU4, respectively. JU2 and JU4 are used to place either +5V or ground at SHDN or TXEN. Pin 3 of these jumpers is ground and pin 1 is +5V. Manual Control of Serial Data Interface If using a source other than a PC to drive the serial data interface of the MAX3510 EV kit (such as a digital pattern generator or microprocessor), remove the shunts on jumpers JU5, JU6, and JU7. Access to the serial data interface is available through these jumpers. See the MAX3510 data sheet for a description of the serial data interface. Quick Basic and Windows 95 are registered trademarks of Microsoft Corp. 2 _______________________________________________________________________________________ MAX3510 Evaluation Kit Output Circuit The MAX3510 features a differential open-collector output with an output impedance of approximately 300Ω. This architecture aids in suppressing 2nd-order distortion (harmonics). To convert to a single-ended output and to match to a 75Ω load, a 2:1 (voltage ratio) transformer (T1) is used. Power is supplied to the output stage through the center tap of this transformer. This feature is essential in reducing transients when switching between transmit and transmit-disable mode. Since most test equipment is supplied with a 50Ω termination impedance, a series 24Ω resistor is provided on the output of the transformer to increase the load impedance to a nominal 75Ω. This places the proper load on the device, but will also reduce the measured output voltage level by 3.5dB. It is essential to consider this when making any measurements with the EV kit. 3.5dB must be added to all measurements of voltage gain and output voltage level (including noise) to arrive at the correct value for a 75Ω system. Use 75Ω test equipment if it is available and take the following steps: 1) Remove the 50Ω output SMA connector and replace it with a 75Ω connector. 2) Remove R5 (the 24Ω series output resistor) and replace it with a 0Ω resistor or some other type of shunt. 3) Be sure to use a 75Ω cable. Analysis Harmonic Distortion A filter will be needed to reject the harmonics generated by the signal source. For this example, a lowpass filter with approximately a 25MHz to 35MHz cutoff frequency will be required. This filter will need to reject at least 20dB of signal at 40MHz. Set the 50Ω signal source for 20MHz and -13dBm. Adjust the amplitude to account for the insertion loss in the filter. Verify with the spectrum analyzer that the second and third harmonics generated by the source are suppressed by at least 70dBc. Connect the filter between the input of the EV kit and the output of the signal source, making sure the proper terminations are being used for this particular filter. Connect a spectrum analyzer to OUTPUT. Set the center frequency for 40MHz and the span for 50MHz or more. Adjust the reference level so that the fundamental (20MHz tone) is within 10dB to 20dB of the reference level. If the fundamental is less than 10dB below the reference level, the harmonic distortion of the spectrum analyzer may prevent accurate measurement of the distortion. Set the gain state to 50 (approximately 16dB of gain). Measure the level of the fundamental, second, and third harmonics on the spectrum analyzer. These readings have units of dBm. To convert from dBm to dBmV in a 50Ω system, use the following equation: X(dBmV) = Y(dBm) + 47dB (50Ω system) Add 3.5dB to this value to account for the voltage drop in the series 24Ω resistor (R5), in dBmV, for a 75Ω load. The gain can now be calculated in dB, and the harmonic distortion can be calculated in dBc. Switching Transients To measure the transmit to transmit-disable transient, the TXEN pin will be driven from an external source. No input signal is applied and the output is viewed on an oscilloscope. Connect OUTPUT to the oscilloscope’s 50Ω input. Set the scope’s time base to 5µs/div and the vertical scale to 5mV/division. Set the pulse generator as follows: Amplitude Duty Cycle Rise/Fall Time Pulse Width Offset 5V 50% 100ns 25µs 2.5V Take care not to drive the MAX3510 TXEN pin below 0V or above VCC. Turn on the power supply. Remove the shunt from jumper JU3 (TXEN) and connect the output of the pulse generator to pin 2 of this jumper. Trigger the oscilloscope from the pulse generator using a convenient method. Set the gain state to 50. _______________________________________________________________________________________ 3 Evaluates: MAX3510 Input Circuit The input circuit of the MAX3510 EV kit is configured with a 1:1 transformer (T2) and a 49.9Ω input resistor. This allows the input to be driven with single-ended 50Ω test equipment. The transformer (T2) is used to generate a differential signal, as rated performance is specified with a differential input drive (typically from a differential lowpass filter). Pads are provided to allow connection of an external differential drive. Additionally, pads are provided for a pair of termination resistors, if needed (R16, R17). If the MAX3510 is to be driven single-ended, the input transformer (T2) must be removed and the undriven input connected to ground through a 0.001µF blocking capacitor. Evaluates: MAX3510 MAX3510 Evaluation Kit A rising and falling edge transient should appear on the scope’s CRT. The peak amplitude of this transient should be less than 7mV. Multiply the value of the measured transient by 1.5, to account for the presence of the 24Ω resistor (R5). The gain may now be changed to show the output transient’s dependence on gain. Output Noise To measure output noise, a spectrum analyzer is used. A postamplifier with less than 10dB noise figure and greater than 40dB gain within the band of interest is needed. With the power supply off, place a 50Ω termination on the input of the EV kit. Turn on the power supply to the MAX3510 EV kit. Using the software, set the device to transmit mode with a gain state of 50 (approximately 16dB of gain). Connect the output of the postamplifier to the spectrum analyzer and the input to the MAX3510 EV kit output. Set the spectrum analyzer as follows: Center Frequency Span Reference Scale IF Bandwidth 35MHz 60MHz -50dBm 10dB/div 1kHz If the spectrum analyzer being used does not have a noise marker function, corrections must be made to account for the IF bandwidth used to make the measurement. Consult the user’s manual for your spectrum analyzer for details. Once the correction is made, the value read from the spectrum analyzer can be converted to a noise density (dBm/Hz), and the above formula can be used. Noise can now be measured at various gains. Output noise in transmit disable mode cannot be measured. Layout Considerations The MAX3510 evaluation board can serve as a guide for your board layout. Particular attention has been paid to the output circuit prior to the transformer and to the DC supply trace to the transformer. The traces leading from output pins 15 and 16 must be as short as possible and symmetrical to reject second harmonics. Since the device can draw 120mA when swinging the maximum signal, the supply trace to the center tap of the transformer must be as wide as is practical to minimize voltage drop. Ground inductance and supply decoupling loop inductance may degrade distortion performance. Returning supply decoupling capacitors for pins 2 and 19 directly to pins 4 and 20, respectively, is recommended. Otherwise, use multiple vias to the ground plane. Power up the postamplifier. If the spectrum analyzer being used has a noise marker function, enable it. The output noise can now be read directly from the spectrum analyzer. Move this marker to 42MHz. Read the value of the noise density from the spectrum analyzer. This noise value is a combination of the output noise of the MAX3510, the gain of the postamp, and the noise figure of the postamp. With the specified noise figure of 10dB, the noise contribution of the postamp may be ignored. Also the series output resistor (R5) reduces the actual measured value by 3.5dB. Use the following equation to arrive at the MAX3510’s output noise: VNOISE = PNOISE + 47dB + 3.5dB + 10 · log (160,000) GAMP where: VNOISE = MAX3510 output noise in dBmV measured in a 160kHz bandwidth PNOISE = Noise density in dBm/Hz read from the spectrum analyzer GAMP = Gain of the postamplifier in dB 4 _______________________________________________________________________________________ J2-25 J2-24 J2-23 J2-22 J2-21 J2-20 J2-9 J2-18 J2-17 J2-16 J2-14 J2-12 J2-11 J2-4 J2-3 J2-1 C7 10µF IN2 GND J2-4 J2-3 J2-2 R6 OPEN R7 OPEN R8 OPEN R9 OPEN J1 R10 OPEN INPUT R11 J1 R1 OPEN SMA 49.9Ω R12 OPEN R13 OPEN C8 0.1µF B1 T2 1:1 VCC1 B2 L3 L2 L1 JU7 1 2 JU6 1 2 JU5 1 2 R17 OPEN R16 OPEN VCC3 VCC2 VCC1 VCC R4 OPEN R3 OPEN R2 OPEN C2 0.001µF C2 0.001µF C1 0.1µF 10 9 8 7 6 5 4 3 2 1 SCLK SDA CS GND VIN- VIN+ GND1 GND VCC1 GND MAX3510 J2-15 J2-10 J2-7 GND SHDN N.C. CEXT2 VOUT- VOUT+ CEXT1 TX_EN VCC2 GND2 11 12 13 14 15 16 17 18 19 20 R14 100k R15 100k C5 0.0033µF C6 0.1µF J2-6 VCC J2-5 C4 0.1µF VCC3 J2-13 1 SHDN JU1 3 C9 0.1µF JU3 VCC2 3 R19 OPEN 2:1 VCC R18 OPEN T1 1 1 JU2 3 R5 24Ω OUTPUT VCC SMA J3 1 JU4 3 Evaluates: MAX3510 IN1 +5V MAX3510 Evaluation Kit Figure 1. MAX3510 EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX3510 MAX3510 Evaluation Kit 1.0" Figure 2. MAX3510 EV Kit Component Placement Guide— Component Side 1.0" Figure 4. MAX3510 EV Kit PC Board Layout—Component Side 6 1.0" Figure 3. MAX3510 EV Kit Component Placement Guide— Solder Side 1.0" Figure 5. MAX3510 EV Kit PC Board Layout—GND Plane _______________________________________________________________________________________ MAX3510 Evaluation Kit Evaluates: MAX3510 1.0" 1.0" Figure 6. MAX3510 EV Kit PC Board Layout—Power Plane Figure 7. MAX3510 EV Kit Component Placement Guide— Solder Side _______________________________________________________________________________________ 7 Evaluates: MAX3510 MAX3510 Evaluation Kit NOTES 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.