MAX 038 Waveform Generator
http://datasheets.maximintegrated.com/en/ds/MAX038.pdf
2. CONTENTS
2.1. Important Sections
[ page 1 ] Applications
[ page 1 ] Ordering Information
[ page 1 ] Pin Configuration
[ page 2 ] Absolute Maximum Ratings
[ page 2 ] Electrical Characteristics
[ page 4 ] Typical Operating Characteristics
[ page 7 ] Pin Description
[ page 8 ] Detailed Description
[ page 16 ] _\-> Layout Considerations
2.2. Circuit Diagram Examples
[ page 8 ] Figure 1: Block Diagram and Basic Operating Circuit
[ page 11 ] Figure 2: Operating Circuit with Sine-Wave Output and 50% Duty Cycle, SYNC and FADJ Disabled
[ page 13 ] Figure 3: Phase-Locked Loop Using Internal Phase Detector
[ page 14 ] Figure 4: Phase-Locked Loop Using External Phase Detector
[ page 14 ] Figure 5: Phase-Locked Loop Using External Frequency Phase Detector
[ page 15 ] Figure 6: Crystal-controlled, Digitally-programmed Frequency Synthesizer, 8kHz to 16MHz with 1kHz Resolution
G = ground, I = input, O = output
[O] Pin 1 REF = 2.50V bandgap voltage reference output
[G] Pin 2 GND = Unspecified ground
3. SUMMARY
3.1. Applications
The MAX038 integrated circuit is a function generator that produces waveforms (pulse, sawtooth, sine, square, and triangle) using only a few external components. Its uses include frequency and pulse-width modulation / demodulation, frequency shift keying, phase-locked loops, and voltage-controlled oscillation.
3.2. Waveform
The output waveform (Pin 19 OUT) is 2 Volts peak-to-peak symmetrical to ground and can drive up to 20 milliAmps of current. Waveform selection is done by setting up a corresponding binary code on two select pins (Pin 3 A0 and Pin 4 A1).
0 = Off (grounded), 1 = On (5 Volts), X = Don't care
[A0][A1] = Output
[ X ][ 1 ] = Sine wave
[ 0 ][ 0 ] = Square wave
The waveform frequency ranges from 0.1 Hz to 20 MHz.
The default frequency is chosen by tapping the bandgap voltage reference output (Pin 1 REF) into the frequency control current input (Pin 10 IIN) using a resistor and a capacitor in low-pass filter configuration (see Figures 1 and 2 in the data sheet).
Frequency modulation (up to 2 MHz) is done by applying a +/- 2.4V control signal (Electrical Characteristics, FADJ) to the frequency adjust input (Pin 8 FADJ). This control signal can either be external, or tapped from the bandgap voltage reference output (Pin 1 REF) using a variable resistor and a capacitor in low-pass filter configuration (see Figure 1 in the data sheet).
3.4. Duty Cycle
The duty cycle varies from 15% to 85%.
Duty-cycle selection is done by applying a +/- 2.3V control signal (Electrical Characteristics, DADJ) to the duty-cycle adjust input (Pin 7 DADJ). This control signal can either be external, or tapped from the bandgap voltage reference output (Pin 1 REF) using a variable resistor and a capacitor in low-pass filter configuration (see Figure 1 in the data sheet).
This facilitates pulse-width modulation and the generation of sawtooth waveforms.
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[ page 8 ] Figure 1: Block Diagram and Basic Operating Circuit
[ page 11 ] Figure 2: Operating Circuit with Sine-Wave Output and 50% Duty Cycle, SYNC and FADJ Disabled
[ page 13 ] Figure 3: Phase-Locked Loop Using Internal Phase Detector
[ page 14 ] Figure 4: Phase-Locked Loop Using External Phase Detector
[ page 14 ] Figure 5: Phase-Locked Loop Using External Frequency Phase Detector
[ page 15 ] Figure 6: Crystal-controlled, Digitally-programmed Frequency Synthesizer, 8kHz to 16MHz with 1kHz Resolution
2.3. Pin Configuration and Description
G = ground, I = input, O = output
[O] Pin 1 REF = 2.50V bandgap voltage reference output
[G] Pin 2 GND = Unspecified ground
[ I ] Pin 3 A0 = Waveform selection input
[ I ] Pin 4 A1 = Waveform selection input
[ I ] Pin 5 COSC = External capacitor for oscillator
[G] Pin 6 GND = Oscillator ground
[ I ] Pin 7 DADJ = Duty-cycle adjust input
[ I ] Pin 8 FADJ = Frequency adjust input
[G] Pin 9 GND = Unspecified ground
[ I ] Pin 10 IIN = Frequency control current input
[G] Pin 11 GND = Unspecified ground
[O] Pin 12 PDO = Phase detector output. Connect to GND if phase detector is not used.
[ I ] Pin 13 PDI = Phase detector reference clock input. Connect to GND if phase detector is not used.
[ I ] Pin 14 SYNC = Permits the internal oscillator to be synchronized with an external signal. Leave open if unused.
[G] Pin 15 DGND = Digital ground
[ I ] Pin 16 DV+ = Digital +5V supply input. Can be left open if SYNC is not used.
[ I ] Pin 17 V+ = +5V supply input
[G] Pin 18 GND = Unspecified ground
[O] Pin 19 OUT = Sine, square, or triangle output
[ I ] Pin 20 V- = -5V supply input
All five GND pins must be tapped directly to a quiet ground close to the device because they are not internally connected (see Figure 1 in the data sheet). The Layout Considerations section of the data sheet recommends a low-impedance ground plane.
3.1. Applications
The MAX038 integrated circuit is a function generator that produces waveforms (pulse, sawtooth, sine, square, and triangle) using only a few external components. Its uses include frequency and pulse-width modulation / demodulation, frequency shift keying, phase-locked loops, and voltage-controlled oscillation.
3.2. Waveform
The output waveform (Pin 19 OUT) is 2 Volts peak-to-peak symmetrical to ground and can drive up to 20 milliAmps of current. Waveform selection is done by setting up a corresponding binary code on two select pins (Pin 3 A0 and Pin 4 A1).
0 = Off (grounded), 1 = On (5 Volts), X = Don't care
[A0][A1] = Output
[ X ][ 1 ] = Sine wave
[ 0 ][ 0 ] = Square wave
[ 1 ][ 0 ] = Triangle wave
3.3. Frequency
The waveform frequency ranges from 0.1 Hz to 20 MHz.
The default frequency is chosen by tapping the bandgap voltage reference output (Pin 1 REF) into the frequency control current input (Pin 10 IIN) using a resistor and a capacitor in low-pass filter configuration (see Figures 1 and 2 in the data sheet).
Frequency modulation (up to 2 MHz) is done by applying a +/- 2.4V control signal (Electrical Characteristics, FADJ) to the frequency adjust input (Pin 8 FADJ). This control signal can either be external, or tapped from the bandgap voltage reference output (Pin 1 REF) using a variable resistor and a capacitor in low-pass filter configuration (see Figure 1 in the data sheet).
3.4. Duty Cycle
The duty cycle varies from 15% to 85%.
Duty-cycle selection is done by applying a +/- 2.3V control signal (Electrical Characteristics, DADJ) to the duty-cycle adjust input (Pin 7 DADJ). This control signal can either be external, or tapped from the bandgap voltage reference output (Pin 1 REF) using a variable resistor and a capacitor in low-pass filter configuration (see Figure 1 in the data sheet).
This facilitates pulse-width modulation and the generation of sawtooth waveforms.
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