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Typ.
Max.
Unit
Conditions
Output Characteristics (Cont’d) Output Impedance
200

IOUT = 5mA
Sine-Wave Amplitude
0.2
0.22
x VSPLY
RL = 100k
(Peak-to-Peak)
Distortion
0.8
3
%
RL = 1M4,5
Unadjusted
0.5
%
RL = 1M4,5
Adjusted
0.3
%
Notes
4 Triangle duty cycle set at 50%, use RA and RB.
5 As RL is decreased distortion will increase, RL 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
Rev. 2.01
5

XR-8038A
SYSTEM DESCRIPTION
The XR-8038A precision waveform generator produces potentiometer between the supplies, with the wiper highly stable and sweepable square, triangle, and sine connected to Pin 1.
waves across eight frequency decades. The device time base employs resistors and a capacitor for frequency and Small frequency deviation (FM) is accomplished by duty cycle determination. The generator contains dual applying modulation voltage to Pins 7 and 8; large comparators, a flip-flop driving a switch, current sources, frequency deviation (sweeping) is accomplished by buffers, and a sine wave convertor. Three identical applying voltage to Pin 8 only. Sweep range is typically frequency outputs are simultaneously available. Supply 1000:1.
voltage can range from 10V to 30V, or ±5V to ±15V with The square wave output is an open collector transistor; dual supplies.
output amplitude swing closely approaches the supply Unadjusted sine wave distortion is typically less than voltage. Triangle output amplitude is typically 1/3 of the 0.7% with the sine wave distortion adjust pin (Pin 1) open.
supply, and sine wave output reaches 0.22 of the supply Distortion levels may be improved by including a 100kΩ
voltage.
+15V
RA
RB

4
5
1
12
6
RL
DCA1
DCA2
SA1
SA2
VCC
10
2
Sine Wave
TC
Timing
Sine
SWO
C1
Circuitry
Converter

7
3
Triangle Wave
FMBI
TWO
U1
S1
8
FMSI
9
Square Wave
Square Wave
SQO
Converter
VEE
XR-8038A
11
–15V

Figure 2. Generalized Test Circuit Rev. 2.01
6

XR-8038A
VCC
11
RA
R
I
2
A
10K

7
8
Buffer
4
10
SWITCH S
VCC
R1
40K
C
RB
Buffer 5
2IB
11
VEE
Figure 3. Detailed View of Current Sources IA and 2IB.
WAVEFORM ADJUSTMENT
The symmetry of all waveforms can be adjusted with the pins 4 and 5 can be shorted together, as shown in external timing resistors. Two possible ways to Figure 6. This connection, however, carries an inherently accomplish this are shown in Figure 4, Figure 5, and larger variation of the duty cycle.
Figure 6. Best results are obtained by keeping the timing With two separate timing resistors the frequency is given resistors RA and RB separate (Figure 4.) RA controls the by:
rising portion of the triangle and sine wave and the “low”
state of the square wave.
f +
1
+
1
t ) t
The magnitude of the triangle waveform is set at 1/3 V
1
2
5
Ǔ
CC;
·R Cǒ1 ) RB
3
A
2R –R
A
B
therefore, the duration of the rising proportion of the triangle is:
or, if RA = RB = R
C·| 2 V - 1 V |
t + C·|DV| +
3
CC 3
CC + 5 R ·C
f + 0.3 (for Figure 4. )
1
I
V
3 A
RC
A
CC
5RA
The duration of the falling portion of the triangle and sine If a single timing resistor is used (Figure 5 and Figure 6), wave and the ”low” state of the square wave is: the frequency is:
C·| 2 V - 1 V |
3
CC 3
CC
R R C
f + 0.15
t + C·|DV| +
+ 5 · A B
2
RC
2I -I
2V
V
3 2R -R
B
A
CC - CC
A
B
5R
5R
B
A
The frequency of oscillation is independent of supply Thus a 50% duty cycle is achieved when RA = RB
voltage, even though none of the voltages are regulated If the duty-cycle is to be varied over a small range about inside the integrated circuit. This is due to the fact that 50%, the connection shown in Figure 5 is slightly more both currents and thresholds are direct, linear function of convenient. If no adjustment of the duty cycle is desired, the supply voltage and thus their effects cancel.
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
R

A
RB

4
5
1
12
6
RL
DCA1 DCA2
SA1 SA2
VCC
10
2
Sine Wave
TC
Timing
Sine
SWO
C1
Circuitry
Converter

7
3
Triangle Wave
FMBI
U1
TWO
8 FMSI
Square Wave
Square Wave
9
SQO
Converter
VEE
11
XR-8038A
–15V
Figure 4. Possible Connection for External Duty Cycle Adjust

+15V

Frequency
Duty Cycle

4
5
1
12
6
RL

DCA1 DCA2
SA1 SA2
VCC
10
2
Sine Wave
TC
Timing
Sine
SWO
Circuitry
Converter

7
3
Triangle Wave
FMBI
U1
TWO
8 FMSI
9
Square Wave
Sine Wave
SQO
Converter
VEE
11
XR-8038A

–15V
Figure 5. Single Potentiometer for External Duty Cycle Adjust Rev. 2.01
8

XR-8038A
+15V

R

4
5
1
12
6
RL
DCA1 DCA2
SA1 SA2
VCC
10
2
Sine Wave
TC
Timing
Sine
SWO
Circuitry
Converter
C1

7
3
Triangle Wave
FMBI
U1
TWO
8 FMSI
9
Square Wave
Square Wave
SQO
Converter
VEE
XR-8038A
11
–15V

Figure 6. No Duty Cycle Adjust
+15V

100K

100K

RB
RA
4
5
1
12
6
R
–15V
L

DCA1
DCA2
SA1 SA2
VCC
10
2
Sine Wave
TC
Timing
Sine
SWO
C1
Circuitry
Converter

7
3
Triangle Wave
FMBI
U1
TWO
8
FMSI
9
Square Wave
Square Wave
SQO
Converter
VEE
XR-8038A
11
–15V

Figure 7. Minimum Sine Wave Distortion Rev. 2.01
9

XR-8038A
SELECTING TIMING COMPONENTS
For any given output frequency, there is a wide range of R
advantage that all waveforms move symmetrically about and C combinations that will work. However, certain ground.