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xr-8038a ...the analog plus company tm precision waveform generator rev. 2.01 1992 exar corporation, 48720 kato road, fremont, ca 94538 (510) 668-7000 fax (510) 668-7017 1 june 1997-3 features low frequency drift, 50ppm/ c, typical simultaneous sine, triangle, and square wave outputs low sine wave distortion - thd 1% high fm and triangle linearity wide frequency range 0.001hz to 200khz variable duty cycle, 2% to 98% low distortion variation with temperature applications precision waveform generation sweep and fm generation tone generation instrumentation and test equipment design precision pll design 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
xr-8038a 2 rev. 2.01 external c 10 3 2 9 comp2 comp1 buffer 5 4 8 7 1 12 6 11 2ib ia switch s sine converter triangle wave output sine adjust sine wave output square wave output flip flop dca1 dca2 timing capacitor fm sweep fm bias v ee v cc figure 1. xr-8038a block diagram 2/3v cc 1/3v cc
xr-8038a 3 rev. 2.01 pin configuration sa1 swo dca1 dca2 fmbi nc nc sa2 tc sqo fmsi 14 lead pdip (0.300o) 1 2 3 4 5 6 7 14 13 12 11 10 9 8 two v cc v ee pin description 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 v cc positive power supply. 7 fmbi i frequency modulation input. 8 fmsi i frequency sweep input. 9 sqo o square wave output. 10 tc i timing capacitor input. 11 v ee negative power supply. 12 sa2 i wave form adjust input 2. 13 nc no connect. 14 nc no connect.
xr-8038a 4 rev. 2.01 dc electrical characteristics test conditions: v s = + 5v to + 15v, t a = 25 c, r l = 1m , r a = r b = 10k , c 1 = 3300pf, s 1 closed, unless otherwise specified. (see figure 2. ) parameter min. typ. max. unit conditions general characteristics supply voltage, v s single supply 10 30 v dual supplies + 5 + 15 v supply current 12 20 ma v s = + 10v 1 frequency characteristics (measured at pin 9) range of adjustment max. operating frequency 200 khz r a = r b , = 1.5k , c 1 = 680pf; r l = 10k lowest practical frequency 0.001 hz r a = r b = 1m , c 1 = 500 f (low leakage capacitor) max. sweep frequency of fm input 100 khz fm sweep range 1000:1 s 1 open 2,3 fm linearity 10:1 ratio 0.2 % s 1 open 3 range of timing resistors 0.5 1000 k values of r a and r b temperature stability 50 ppm/ c t a = 0 c to 70 c power supply stability 0.05 %/v 10v v s 30v or + 5v v s 15v output characteristics square-wave measured at pin 9 amplitude (peak-to-peak) 0.9 0.98 x v sply r l = 100k saturation voltage 0.2 0.5 v i sink = 2ma rise time 100 ns r l = 4.7k fall time 40 ns r l = 4.7k duty cycle adjustment 2 98 % triangle/sawtooth/ramp measured at pin 3 amplitude (peak-to-peak) 0.3 0.33 x v sply r l = 100k linearity 0.1 % notes 1 currents through r a and r b not included. 2 v supply = 20v. 3 apply sweep voltage at pin 8. v cc - (1/3 v supply - 2) v pin 8 v cc v supply = total supply voltage across the ic specifications are subject to change without notice
xr-8038a 5 rev. 2.01 dc electrical characteristics (cont'd) test conditions: v s = + 5v to + 15v, t a = 25 c, r l = 1m , r a = r b = 10k , c 1 = 3300pf, s 1 closed, unless otherwise specified. (see figure 2. ) parameter min. typ. max. unit conditions output characteristics (cont'd) output impedance 200 i out = 5ma sine-wave amplitude (peak-to-peak) 0.2 0.22 x v sply r l = 100k distortion 0.8 3 % r l = 1m 4,5 unadjusted 0.5 % r l = 1m 4,5 adjusted 0.3 % notes 4 triangle duty cycle set at 50%, use r a and r b . 5 as r l is decreased distortion will increase, r l min 50k . 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 . . . . . .
xr-8038a 6 rev. 2.01 system description 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. 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 100k w potentiometer between the supplies, with the wiper connected to pin 1. 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. converter tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry converter s1 c1 +15v 15v sine wave triangle wave square wave 10 112 2 3 9 5 46 7 8 11 xr-8038a square wave sine v cc figure 2. generalized test circuit r a r b v ee r l
xr-8038a 7 rev. 2.01 10k 40k 7 8 buffer buffer 4 switch s 10 5 c 11 11 i a r a r b r 2 r 1 v cc v ee v cc 2i b figure 3. detailed view of current sources i a and 2i b . waveform adjustment 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 r a and r b separate ( figure 4. ) r a controls the rising portion of the triangle and sine wave and the alowo state of the square wave. the magnitude of the triangle waveform is set at 1/3 v cc ; therefore, the duration of the rising proportion of the triangle is: t 1 c | v | i a c | 2 3 v cc - 1 3 v cc | v cc 5 r a 5 3 r a c the duration of the falling portion of the triangle and sine wave and the olowo state of the square wave is: t 2 c | v | 2 i b -i a c | 2 3 v cc - 1 3 v cc | 2 v cc 5 r b - v cc 5 r a 5 3 r a r b c 2 r a -r b thus a 50% duty cycle is achieved when r a = r b 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, 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. with two separate timing resistors the frequency is given by: f 1 t 1 t 2 1 5 3 r a c 1 r b 2 r a r b or, if r a = r b = r f 0.3 rc ( for figure 4. ) if a single timing resistor is used ( figure 5 and figure 6 ), the frequency is: f 0.15 rc 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.
xr-8038a 8 rev. 2.01 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%. tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry sine converter c1 +15v 15v sine wave triangle wave square wave 10 112 2 3 9 5 46 7 8 11 xr-8038a r a r b r l v ee v cc square wave converter figure 4. possible connection for external duty cycle adjust tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry sine duty cycle frequency +15v 15v 10 1 12 2 3 9 5 46 7 8 11 xr-8038a sine wave triangle wave square wave r l v cc v ee converter sine wave converter figure 5. single potentiometer for external duty cycle adjust
xr-8038a 9 rev. 2.01 tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry sine converter c1 r +15v 15v sine wave triangle wave square wave 10 112 2 3 9 5 46 7 8 11 figure 6. no duty cycle adjust xr-8038a converter square wave v cc v ee r l tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry sine converter square wave converter c1 100k 100k +15v 15v 15v sine wave triangle wave 10 1 12 2 3 9 5 46 7 8 11 figure 7. minimum sine wave distortion v cc v ee square wave r a xr-8038a r b r l
xr-8038a 10 rev. 2.01 selecting timing components 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 0.1 a 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 1 a to 1ma. if pins 7 and 8 are shorted together, the magnitude of the charging current due to r a can be calculated from: i r 1 v cc ( r 1 r 2 ) 1 r a v cc 5 r a a similar calculation holds for r b . 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 r a c t . 2. a 0.1 f capacitor is tied from pin 7 and 8 to ground. note: - this is only needed if the duty cycle is powered up with r a >>r b . 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 +v cc and ground. a split power supply has the advantage that all waveforms move symmetrically about ground. 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 +v cc ). by altering this voltage, frequency modulation is performed. 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 8k ); with it, this impedance increases to (r // 8k 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 v sweep =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 v cc to 2/3 v cc -2v.
xr-8038a 11 rev. 2.01 tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi u1 timing circuitry sine converter c1 fm +15v 15v sine wave triangle wave square wave 10 112 2 3 9 5 46 7 8 11 tc sa1 sa2 swo two sqo dca2 dca1 fmbi fmsi c1 u1 +15v 15v sweep voltage 10 112 2 3 9 5 46 7 8 11 figure 8. frequency modulator figure 9. frequency sweep r l xr-8038a v cc v ee converter square wave r a r b r a r b r l v cc v ee converter square wave timing circuitry sine converter sine wave triangle wave square wave v cc - (v sup - 2) < = v in & < = v cc xr-8038a
xr-8038a 12 rev. 2.01 figure 10. power dissipation vs. supply voltage figure 11. frequency drift vs. power supply figure 12. sine wave thd vs. frequency current consumption supply voltage 5101520 2530 5 10 15 20 -55 c 25 c 125 c normalized frequency 5101520 2530 0.98 0.99 1.00 1.01 1.02 1.03 10hz 100hz 1khz 10khz 100khz 1mhz 0 2 4 6 8 10 12 distortion % supply voltage frequency unadjusted adjusted
xr-8038a 13 rev. 2.01 14 lead plastic dual-in-line (300 mil pdip) rev. 1.00 14 1 8 7 d e b 1 a 1 e 1 e a l b seating plane symbol min max min max inches a 0.145 0.210 3.68 5.33 a 1 0.015 0.070 0.38 1.78 a 2 0.115 0.195 2.92 4.95 b 0.014 0.024 0.36 0.56 b 1 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 e 1 0.240 0.280 6.10 7.11 e 0.100 bsc 2.54 bsc e a 0.300 bsc 7.62 bsc e b 0.310 0.430 7.87 10.92 l 0.115 0.160 2.92 4.06 a 0 15 0 15 millimeters a a 2 c note: the control dimension is the inch column e b e a
xr-8038a 14 rev. 2.01 notes
xr-8038a 15 rev. 2.01 notes
xr-8038a 16 rev. 2.01 notice exar corporation reserves the right to make changes to the products contained in this publication in order to im- prove design, performance or reliability. exar corporation assumes no responsibility for the use of any circuits de- scribed 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 circum- stances. copyright 1992 exar corporation datasheet june 1997 reproduction, in part or whole, without the prior written consent of exar corporation is prohibited.

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