XR-8038A ...the analog plus Precision Waveform Generator company TM June 1997-3 FEATURES APPLICATIONS Low Frequency Drift, 50ppm/°C, Typical Precision Waveform Generation Simultaneous Sine, Triangle, and Square Wave Outputs Sweep and FM Generation Low Sine Wave Distortion - THD 1% Instrumentation and Test Equipment Design High FM and Triangle Linearity Precision PLL Design Tone Generation Wide Frequency Range 0.001Hz to 200KHz Variable Duty Cycle, 2% to 98% Low Distortion Variation with Temperature GENERAL DESCRIPTION The XR-8038A is a precision waveform generator IC capable of producing sine, square, triangular, sawtooth, and pulse waveforms, with a minimum number of external components and adjustments. The XR-8038A allows the elimination of the external distortion adjusting resistor which greatly improves the temperature drift of distortion, as well as lowering external parts count. Its operating frequency can be selected over eight decades of frequency, from 0.001Hz to 200kHz, by the choice of external R-C components. The frequency of oscillation is highly stable over a wide range of temperature and supply voltage changes. Both full frequency sweeping as well as smaller frequency variations (FM) can be accomplished with an external control voltage. Each of the three basic waveform outputs, (i.e., sine, triangle and square) are simultaneously available from independent output terminals. The XR-8038A monolithic waveform generator uses advanced processing technology and Schottky-barrier diodes to enhance its frequency performance. ORDERING INFORMATION Part No. Package Operating Temperature Range XR-8038ACP 14 Lead 300 mil PDIP 0°C to 70°C Rev. 2.01 1992 EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 (510) 668-7000 FAX (510) 668-7017 1 XR-8038A Triangle Wave Output Timing Capacitor VCC 6 10 3 Sine Adjust 1 12 Buffer 4 DCA1 Sine Converter Ia 5 DCA2 8 2/3VCC FM Sweep C Flip– Flop Switch S 1/3VCC FM Bias 7 Comp2 2Ib 11 VEE Figure 1. XR-8038A Block Diagram Rev. 2.01 2 2 9 Comp1 External Sine Wave Output Square Wave Output XR-8038A PIN CONFIGURATION SA1 SWO TWO DCA1 DCA2 VCC FMBI 1 14 2 13 3 12 4 11 5 10 6 9 7 8 NC NC SA2 VEE TC SQO FMSI 14 Lead PDIP (0.300”) PIN DESCRIPTION ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Pin # Symbol Type Description 1 SA1 I Wave Form Adjust Input 1. 2 SWO O Sine Wave Output. 3 TWO O Triangle Wave Output. 4 DCA1 I Duty Cycle Adjustment Input. 5 DCA2 I Duty Cycle Adjustment Input. 6 VCC 7 FMBI I Frequency Modulation Input. 8 FMSI I Frequency Sweep Input. 9 SQO O Square Wave Output. 10 TC I Timing Capacitor Input. Positive Power Supply. 11 VEE 12 SA2 Negative Power Supply. 13 NC No Connect. 14 NC No Connect. I Wave Form Adjust Input 2. Rev. 2.01 3 XR-8038A DC ELECTRICAL CHARACTERISTICS Test Conditions: VS = +5V to +15V, TA = 25°C, RL = 1M, RA = RB = 10k, C1 = 3300pF, S1 closed, unless otherwise specified. (See Figure 2.) Parameter Min. Typ. Max. Unit Conditions General Characteristics Supply Voltage, VS Single Supply 10 30 V Dual Supplies +5 +15 V 20 mA VS = +10V1 kHz RA = RB, = 1.5k, C1 = 680pF; RL = 10K 0.001 Hz RA = RB = 1M, C1= 500F (Low Leakage Capacitor) 100 kHz Supply Current 12 Frequency Characteristics (Measured at Pin 9) Range of Adjustment Max. Operating Frequency 200 Lowest Practical Frequency Max. Sweep Frequency of FM Input FM Sweep Range FM Linearity 10:1 Ratio Range of Timing Resistors S1 Open2,3 1000:1 0.2 0.5 1000 % S1 Open3 K Values of RA and RB Temperature Stability 50 PPM/°C TA = 0°C to 70°C Power Supply Stability 0.05 %/V 0.98 x VSPLY RL = 100k V ISINK = 2mA 10V VS 30V or +5V VS 15V Output Characteristics Square-Wave Amplitude (Peak-to-Peak) Measured at Pin 9 0.9 Saturation Voltage 0.2 Rise Time 100 ns RL = 4.7k Fall Time 40 ns RL = 4.7k Duty Cycle Adjustment 0.5 2 98 % Triangle/Sawtooth/Ramp Amplitude (Peak-to-Peak) Measured at Pin 3 0.3 Linearity 0.33 x VSPLY 0.1 % Notes 1 Currents through R and R not included. A B 2V SUPPLY = 20V. 3 Apply sweep voltage at Pin 8. VCC - (1/3 VSUPPLY - 2) VPIN 8 VCC VSUPPLY = Total Supply Voltage across the IC Specifications are subject to change without notice Rev. 2.01 4 RL = 100k XR-8038A DC ELECTRICAL CHARACTERISTICS (CONT’D) Test Conditions: VS = +5V to +15V, TA = 25°C, RL = 1M, RA = RB = 10k, C1 = 3300pF, S1 closed, unless otherwise specified. (See Figure 2.) Parameter Min. Typ. Max. Unit Conditions 200 IOUT = 5mA 0.22 x VSPLY RL = 100k % RL = 1M4,5 RL = 1M4,5 Output Characteristics (Cont’d) Output Impedance Sine-Wave Amplitude (Peak-to-Peak) Distortion 0.2 0.8 3 Unadjusted 0.5 % Adjusted 0.3 % Notes 4 Triangle duty cycle set at 50%, use R and R . A B 5 As R is decreased distortion will increase, R min [ 50K. L L Bold face parameters are covered by production test and guaranteed over operating temperature range. Specifications are subject to change without notice ABSOLUTE MAXIMUM RATINGS Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V Power Dissipation (package limitation) Plastic Package . . . . . . . . . . . . . . . . . . 625mW Derate Above +25°C . . . . . . . . . . . . . 5mW/°C Storage Temperature Range . . . . . . -65°C to +150°C Rev. 2.01 5 XR-8038A SYSTEM DESCRIPTION potentiometer between the supplies, with the wiper connected to Pin 1. The XR-8038A precision waveform generator produces highly stable and sweepable square, triangle, and sine waves across eight frequency decades. The device time base employs resistors and a capacitor for frequency and duty cycle determination. The generator contains dual comparators, a flip-flop driving a switch, current sources, buffers, and a sine wave convertor. Three identical frequency outputs are simultaneously available. Supply voltage can range from 10V to 30V, or ±5V to ±15V with dual supplies. Small frequency deviation (FM) is accomplished by applying modulation voltage to Pins 7 and 8; large frequency deviation (sweeping) is accomplished by applying voltage to Pin 8 only. Sweep range is typically 1000:1. The square wave output is an open collector transistor; output amplitude swing closely approaches the supply voltage. Triangle output amplitude is typically 1/3 of the supply, and sine wave output reaches 0.22 of the supply voltage. Unadjusted sine wave distortion is typically less than 0.7% with the sine wave distortion adjust pin (Pin 1) open. Distortion levels may be improved by including a 100kΩ +15V RA 10 TC C1 7 FMBI RB 4 5 DCA1 DCA2 Timing Circuitry 1 SA1 12 SA2 Sine Converter RL 6 VCC SWO TWO U1 2 Sine Wave 3 Triangle Wave 9 Square Wave S1 8 FMSI Square Wave Converter SQO VEE XR-8038A 11 –15V Figure 2. Generalized Test Circuit Rev. 2.01 6 XR-8038A VCC 11 RA IA R2 10K 7 8 Buffer 4 VCC 10 SWITCH S R1 40K C RB Buffer 5 2IB 11 VEE Figure 3. Detailed View of Current Sources IA and 2IB. WAVEFORM ADJUSTMENT pins 4 and 5 can be shorted together, as shown in Figure 6. This connection, however, carries an inherently larger variation of the duty cycle. The symmetry of all waveforms can be adjusted with the external timing resistors. Two possible ways to accomplish this are shown in Figure 4, Figure 5, and Figure 6. Best results are obtained by keeping the timing resistors RA and RB separate (Figure 4.) RA controls the rising portion of the triangle and sine wave and the “low” state of the square wave. With two separate timing resistors the frequency is given by: f+ The magnitude of the triangle waveform is set at 1/3 VCC; therefore, the duration of the rising proportion of the triangle is: t1 + 1 + t1 ) t2 5 3 ǒ 1 RB ·R AC 1 ) 2R A–R B Ǔ or, if RA = RB = R C·| 23 V CC- 13 V CC| C·|DV | + + 5 R A·C V 3 IA CC f + 0.3 RC ( for Figure 4. ) 5R A If a single timing resistor is used (Figure 5 and Figure 6), the frequency is: The duration of the falling portion of the triangle and sine wave and the ”low” state of the square wave is: t2 + 2 1 C·| 3 V CC- 3 V CC| R R C C·|DV | + + 5· A B 2 V V 3 2R A-R B 2I B-I A CC - CC 5R B 5R f + 0.15 RC A The frequency of oscillation is independent of supply voltage, even though none of the voltages are regulated inside the integrated circuit. This is due to the fact that both currents and thresholds are direct, linear function of the supply voltage and thus their effects cancel. Thus a 50% duty cycle is achieved when RA = RB If the duty-cycle is to be varied over a small range about 50%, the connection shown in Figure 5 is slightly more convenient. If no adjustment of the duty cycle is desired, Rev. 2.01 7 XR-8038A DISTORTION ADJUSTMENT To minimize sine wave distortion, two potentiometers can be connected as shown in Figure 7. This configuration allows a reduction of sine wave distortion close to 0.5%. +15V RA RB 4 10 C1 TC 5 1 DCA1 DCA2 SA1 SA2 Timing Circuitry Sine Converter 7 FMBI VCC SWO TWO U1 8 FMSI RL 6 12 Square Wave Converter SQO 2 Sine Wave 3 Triangle Wave 9 Square Wave VEE XR-8038A 11 –15V Figure 4. Possible Connection for External Duty Cycle Adjust +15V Frequency Duty Cycle 4 5 DCA1 DCA2 10 TC Timing Circuitry 7 FMBI 1 12 SA1 SA2 Sine Converter 6 SWO TWO U1 8 FMSI Sine Wave Converter RL VCC SQO 2 Sine Wave 3 Triangle Wave 9 Square Wave VEE XR-8038A 11 –15V Figure 5. Single Potentiometer for External Duty Cycle Adjust Rev. 2.01 8 XR-8038A +15V R 4 5 DCA1 DCA2 10 TC Timing Circuitry C1 7 FMBI 1 RL 6 12 SA1 SA2 VCC Sine Converter 2 Sine Wave 3 Triangle Wave 9 Square Wave SWO U1 TWO 8 FMSI Square Wave Converter VEE SQO XR-8038A 11 –15V Figure 6. No Duty Cycle Adjust +15V 100K 4 5 DCA1 10 C1 TC 7 FMBI 100K RB RA DCA2 Timing Circuitry 1 12 6 Sine Converter SWO U1 TWO 8 FMSI Square Wave Converter VEE RL SQO 2 Sine Wave 3 Triangle Wave 9 Square Wave XR-8038A 11 –15V Figure 7. Minimum Sine Wave Distortion Rev. 2.01 9 –15V VCC SA1 SA2 XR-8038A SELECTING TIMING COMPONENTS advantage that all waveforms move symmetrically about ground. For any given output frequency, there is a wide range of R and C combinations that will work. However, certain constraints are placed upon the magnitude of the charging current for optimum performance. At the low end, currents of less than 0.1mA are undesirable because circuit leakages will contribute significant errors at high temperatures. At higher currents (1 > 5mA), transistor betas and saturation voltages will contribute increasingly large errors. Optimum performance will be obtained for charging currents of 1mA to 1mA. If pins 7 and 8 are shorted together, the magnitude of the charging current due to RA can be calculated from: The square wave output is not committed. A load resistor can be connected to a different power supply, as long as the applied voltage remains within the breakdown capability of the waveform generator (30V). In this way, the square wave output will be TTL compatible (load resistor connected to +5V) while the waveform generator itself is powered from a higher supply voltage. FREQUENCY MODULATION AND SWEEP The frequency of the waveform generator is an inverse function of the dc voltage at pin 8 (measured from +VCC). By altering this voltage, frequency modulation is performed. R 1·V CC V I+ · 1 + CC ( R 1 ) R 2) R A 5R A A similar calculation holds for RB. For small deviations (e.g., +10%), the modulating signal can be applied to pin 8 by merely providing ac coupling with a capacitor, as shown in Figure 8. An external resistor between pins 7 and 8 is not necessary, but it can be used to increase input impedance. Without it (i.e. pins 7 and 8 connected together), the input impedance is 8KW); with it, this impedance increases to (R // 8KW). When the duty cycle is greater than 60%, the device may not oscillate every time, unless: 1. The rise times of the V+ are 10X times slower than RA@CT. 2. A 0.1mF capacitor is tied from pin 7 and 8 to ground. For larger FM deviations or for frequency sweeping, the modulating signal is applied between the positive supply voltage and pin 8 (Figure 9.) In this way the entire bias for the current sources is created by the modulating signal and a very large (e.g. 1000:1) sweep range is obtained (f=0 at VSWEEP=0). Care must be taken, however, to regulate the supply voltage; in this configuration the charge current is no longer a function of the supply voltage (yet the trigger thresholds still are) and thus the frequency becomes dependent on the supply voltage. The potential on pin 8 may be swept from VCC to 2/3 VCC-2V. NOTE: This is only needed if the duty cycle is powered up with RA >>RB . SINGLE-SUPPLY AND SPLIT-SUPPLY OPERATION The waveform generator can be operated either from a single power supply (10V to 30V) or a dual power supply (+5V to +15V). With a single power supply the average levels of the triangle and sine wave are at exactly one half of the supply voltage, while the square wave alternates between +VCC and ground. A split power supply has the Rev. 2.01 10 XR-8038A +15V RA RB 4 5 DCA1 DCA2 C1 10 7 8 TC Timing Circuitry FMBI 1 12 VCC SA1 SA2 Sine Converter 2 Sine Wave 3 Triangle Wave 9 Square Wave SWO U1 TWO FMSI Square Wave Converter FM RL 6 SQO VEE XR-8038A 11 –15V Figure 8. Frequency Modulator +15V RA RB 4 5 DCA1 DCA2 C1 10 7 8 Sweep Voltage VCC - (VSUP - 2) < = VIN & < = VCC TC FMBI Timing Circuitry 1 12 SA1 SA2 Sine Converter U1 RL 6 VCC 2 Sine Wave 3 Triangle Wave 9 Square Wave SWO TWO FMSI Square Wave Converter SQO VEE XR-8038A 11 –15V Figure 9. Frequency Sweep Rev. 2.01 11 XR-8038A 1.03 1.02 Normalized Frequency Current Consumption 20 15 -55°C 125°C 25°C 10 1.01 1.00 0.99 0.98 5 5 10 15 20 25 5 30 10 15 Supply Voltage 25 Supply Voltage Figure 10. Power Dissipation vs. Supply Voltage Figure 11. Frequency Drift vs. Power Supply 12 10 Distortion – % 20 8 6 4 Unadjusted 2 0 10Hz Adjusted 100Hz 1kHz 10kHz 100kHz 1MHz Frequency Figure 12. Sine Wave THD vs. Frequency Rev. 2.01 12 30 XR-8038A 14 LEAD PLASTIC DUAL-IN-LINE (300 MIL PDIP) Rev. 1.00 14 8 1 7 E1 E D Seating Plane A2 A L α A1 B INCHES SYMBOL eA eB B1 e MILLIMETERS MIN MAX MIN MAX A 0.145 0.210 3.68 5.33 A1 0.015 0.070 0.38 1.78 A2 0.115 0.195 2.92 4.95 B 0.014 0.024 0.36 0.56 B1 0.030 0.070 0.76 1.78 C 0.008 0.014 0.20 0.38 D 0.725 0.795 18.42 20.19 E 0.300 0.325 7.62 8.26 E1 0.240 0.280 6.10 7.11 e 0.100 BSC 2.54 BSC eA 0.300 BSC 7.62 BSC eB 0.310 0.430 7.87 10.92 L 0.115 0.160 2.92 4.06 α 0° 15° 0° 15° Note: The control dimension is the inch column Rev. 2.01 13 C XR-8038A Notes Rev. 2.01 14 XR-8038A Notes Rev. 2.01 15 XR-8038A NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user’s specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 1992 EXAR Corporation Datasheet June 1997 Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. Rev. 2.01 16