MAX038EVKIT MAXIM | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 9
Technical content
Not Recommended for New Designs This product was manufactured for Maxim by an outside wafer foundry using a process that is no longer available. It is not recommended for new designs. The data sheet remains available for existing users. A Maxim replacement or an industry second-source may be available. Please see the QuickView data sheet for this part or contact technical support for assistance. For further information, contact Maxim’s Applications Tech Support.
Evaluates: MAX038 MAX038 Evaluation Kit The MAX038 evaluation kit (EV kit) is a high-frequency function generator capable of producing accurate tri- angle/sawtooth, sine, and square/pulse waveforms up to 10MHz, using the supplied components. Output fre- quency and duty cycle are easily adjusted with on- board potentiometers. Removable jumpers select sine, square, or triangle waveforms, or fix the duty cycle at 50%. The output is buffered with a MAX442 amplifier capable of driving a 50 Ω coaxial cable. The MAX038 EV kit is fully assembled and tested. ' 325kHz to 10MHz Operation ' Adjustable Duty Cycle ' 2.5V Reference Output ' TTL-Compatible SYNC Output ' Fully Assembled and Tested The MAX038 EV kit is a fully assembled and tested board. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. 1) Connect a +5V supply to the pad marked +5V. Connect a -5V supply to the pad marked -5V. Connect ground(s) to the GND pad. 2) Connect an oscilloscope to the BNC jack marked OUTPUT through a terminated 50 Ω cable. The MAX038 output prior to the amplifier stage may also be monitored using an oscilloscope probe at the OUT pad. 3) Place the shunt across pins 2 and 3 of JU4 for 50% duty cycle. Place the shunt across pins 1 and 2 of DESIGNATION QTY DESCRIPTION U1 1 MAX038CPP U2 1 MAX442CPA C1 1 82pF capacitor C2, C3, C5, C7, C9, C10, C11, C12 8 0.1µF capacitors C4, C6, C8 3 4.7µF capacitors R1, R2 2 20kΩ potentiometers R3 1 50kΩ potentiometer R4, R5 2 10kΩ , 5% resistors R6 1 51Ω , 5% resistor R7, R8 2 270Ω , 5% resistors R9, R10, R11 3 0Ω resistors R12 1 3.3kΩ , 5% resistor JU1, JU2, JU5 3 2-pin headers JU3, JU4 2 3-pin headers None 5 Shunts J1 1 BNC jack PART MAX038EVKIT-DIP 0°C to +70°C TEMP. RANGE BOARD TYPE Through-Hole For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468.
that there is a shunt on JU5. 5) Apply power and verify the output waveform. Table 1. These jumpers set address pins A0 and A1 to A1 pads and removing the shunts on JU1 and JU2. current (position of R3) as specified by formula [1]. shunt and placing a current meter across the JU5 pins. completely. Limit the external FADJ voltage to ±2.4V. the JU4 shunt on pins 2 and 3, the DADJ pin is grounded. Grounding the DADJ pin fixes the duty cycle at 50%. Table 1. Waveform Jumper Select Table 2. Frequency and Duty-Cycle Jumper Select
The MAX038 output amplitude is fixed at 2V p-p. The MAX038 output is capable of driving a capacitive load up to 90pF. The MAX442 amplifier buffers the MAX038 output to a 50 Ω coaxial cable. The MAX442 is set at a gain of 2V/V, so that the output amplitude remains 1V/V after the 50 Ω back termination. The EV kit’s OUT pad provides access to the output of the MAX038 prior to the MAX442 buffer stage. The MAX442 output connects to the BNC connector through a 50 Ω resistor to back terminate a 50Ω coaxial cable. When a terminated 50 Ω cable is connected, this resistor forms a voltage divider with the load impedance, which attenuates the signal by one-half. The MAX442 is operated with a 2V/V closed-loop gain to provide unity gain at the 50 Ω cable’s output. The MAX442 is actually a 2-channel amplifier. A built- in multiplexer allows either of two input signals to be selected. TTL-level address pin A0 selects either IN0 or IN1. The MAX038 output is connected to MAX442 input IN0. IN1 is unused and connected to ground; it may be used by cutting the JU7 trace, thus discon - necting IN1 from ground. Likewise, the MAX442 address pin A0 can be disconnected from ground by cutting the JU8 trace. Pull up A0 to +5V to select IN1. See the MAX442 data sheet for additional operation details. Reference Voltage The MAX038 includes a 2.5V bandgap reference capa - ble of sourcing 4mA and sinking 100 µA. Access to the reference voltage is provided at the REF pad. The ref - erence voltage is primarily used to provide stable cur - rent to IIN and to bias DADJ and FADJ. Extending the Output Frequency Range The components supplied with the EV kit allow an out - put frequency range of 325kHz to 10MHz. The frequen - cy range is controlled primarily by the oscillator capaci - tor (C1) and the input current, which is a function of the reference voltage and potentiometer R3. The resulting frequency range can be shifted up or down depending on the value of C1. Refer to the Output Frequency vs. Input Current graph which appears in the Typical Operating Characteristics of the MAX038 data sheet. The upper end of the range can be extended by reduc - ing C1. The lower end of the range can be reduced by increasing the value of C1. Take care when selecting alternate capacitors if stable operation over tempera - ture is desired. Ceramic capacitors with low tempera - ture coefficients give the best results. Refer to the Selecting Resistors and Capacitors section of the MAX038 data sheet for further details. Sync Output and Phase-Detector Input Refer to the SYNC Output and Phase Detector sections of the MAX038 data sheet for details of circuit synchro - nization. Access to the Phase Detector Input (PDI) and SYNC is provided at pads PDI and SYNC. High-speed transient currents in DGND and DV+ can cause a switching spike in the output waveform at the zero-crossing point. A lowpass output filter, as shown in Figure 3 of the MAX038 data sheet, may be used to greatly reduce the spike. Complete LC filter assemblies (S3LP series) are available from Coilcraft (phone: 708-639-6400). If the SYNC output is not required, dis - abling the SYNC circuit will eliminate the switching spike. Cut the trace between the DV+ and +5V pads to disable the SYNC output. Evaluates: MAX038 MAX038 Evaluation Kit
321 GND
Figure 1. MAX038 EV Kit Schematic
Figure 2. MAX038 EV Kit Component Placement Guide—Component Side
Figure 3. MAX038 EV Kit PC Board Layout—Component Side
Figure 4. MAX038 EV Kit PC Board Layout—Solder Side
Evaluates: MAX038 MAX038 Evaluation Kit NOTES Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu it 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 © 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.