XR-8038ACMD [EXAR]
Waveform Generation, BIPolar, PDSO14;
| 型号： | XR-8038ACMD |
| 厂家： | 
EXAR CORPORATION |
| 描述： | Waveform Generation, BIPolar, PDSO14 |
| 文件： | 总16页 (文件大小：152K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
XR-8038A
Precision Waveform
Generator
...the analog plus companyTM
June 1997-3
FEATURES
APPLICATIONS
D Precision Waveform Generation
D Sweep and FM Generation
D Tone Generation
D Low Frequency Drift, 50ppm/°C, Typical
D Simultaneous Sine, Triangle, and Square Wave
Outputs
D Low Sine Wave Distortion - THD ] 1%
D High FM and Triangle Linearity
D Instrumentation and Test Equipment Design
D Precision PLL Design
D Wide Frequency Range 0.001Hz to 200KHz
D Variable Duty Cycle, 2% to 98%
D 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
Operating
Temperature Range
Part No.
Package
14 Lead 300 mil PDIP
XR-8038ACP
0°C to 70°C
Rev. 2.01
E1992
EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 z (510) 668-7000 z FAX (510) 668-7017
1
XR-8038A
Timing
Capacitor
Triangle Wave
Output
Sine
Adjust
V
CC
6
10
3
1
12
Buffer
4
DCA1
5
Sine Wave
Output
Sine
Converter
Ia
2
9
DCA2
Square
Wave
Output
8
2/3V
CC
FM Sweep
Comp1
C
External
Flip–
Flop
Switch S
FM Bias
1/3V
CC
7
Comp2
2Ib
11
V
EE
Figure 1. XR-8038A Block Diagram
Rev. 2.01
2
XR-8038A
PIN CONFIGURATION
SA1
1
2
3
4
5
6
7
14
13
12
NC
NC
SA2
SWO
TWO
DCA1
11 V
10
EE
TC
SQO
FMSI
DCA2
V
CC
9
8
FMBI
14 Lead PDIP (0.300”)
PIN DESCRIPTION
Pin #
1
Symbol
SA1
Type Description
I
O
O
I
Wave Form Adjust Input 1.
Sine Wave Output.
2
SWO
TWO
DCA1
DCA2
VCC
3
Triangle Wave Output.
Duty Cycle Adjustment Input.
Duty Cycle Adjustment Input.
Positive Power Supply.
Frequency Modulation Input.
Frequency Sweep Input.
Square Wave Output.
Timing Capacitor Input.
Negative Power Supply.
Wave Form Adjust Input 2.
No Connect.
4
5
I
6
7
FMBI
FMSI
SQO
TC
I
I
8
9
O
I
10
11
12
13
14
VEE
SA2
I
NC
NC
No Connect.
Rev. 2.01
3
XR-8038A
DC ELECTRICAL CHARACTERISTICS
Test Conditions: V = +5V to +15V, T = 25°C, R = 1MW, R = R = 10kW, C = 3300pF, S closed, unless
S
A
L
A
B
1
1
otherwise specified. (See Figure 2.)
Parameter
Min.
Typ.
Max.
Unit
Conditions
General Characteristics
Supply Voltage, VS
Single Supply
10
+5
30
+15
20
V
V
Dual Supplies
Supply Current
12
mA
VS = +10V1
Frequency Characteristics (Measured at Pin 9)
Range of Adjustment
Max. Operating Frequency
200
kHz
Hz
RA = RB, = 1.5kW, C1 = 680pF;
RL = 10K
Lowest Practical Frequency
0.001
100
RA = RB = 1MW, C1= 500mF
(Low Leakage Capacitor)
Max. Sweep Frequency of FM
Input
kHz
FM Sweep Range
FM Linearity 10:1 Ratio
Range of Timing Resistors
Temperature Stability
Power Supply Stability
Output Characteristics
Square-Wave
1000:1
0.2
S1 Open2,3
%
S1 Open3
0.5
0.9
1000
KW
Values of RA and RB
50
PPM/°C TA = 0°C to 70°C
0.05
%/V
10Vꢀ VS ꢀ 30V or +5V ꢀ VS ꢀ 15V
Measured at Pin 9
RL = 100kW
ISINK = 2mA
RL = 4.7kW
Amplitude (Peak-to-Peak)
Saturation Voltage
Rise Time
0.98
0.2
100
40
x VSPLY
0.5
98
V
ns
ns
%
Fall Time
RL = 4.7kW
Duty Cycle Adjustment
Triangle/Sawtooth/Ramp
Amplitude (Peak-to-Peak)
Linearity
2
Measured at Pin 3
0.3
0.33
0.1
x VSPLY
%
RL = 100kW
Notes
1
Currents through RA and RB not included.
2 VSUPPLY = 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
XR-8038A
DC ELECTRICAL CHARACTERISTICS (CONT’D)
Test Conditions: V = +5V to +15V, T = 25°C, R = 1MW, R = R = 10kW, C = 3300pF, S closed, unless
S
A
L
A
B
1
1
otherwise specified. (See Figure 2.)
Parameter
Min.
Typ.
Max.
Unit
Conditions
Output Characteristics (Cont’d)
Output Impedance
200
W
IOUT = 5mA
Sine-Wave Amplitude
(Peak-to-Peak)
0.2
0.22
x VSPLY
RL = 100kW
Distortion
Unadjusted
Adjusted
0.8
0.5
0.3
3
%
%
%
RL = 1MW4,5
RL = 1MW4,5
Notes
4
Triangle duty cycle set at 50%, use RA and RB.
As RL is decreased distortion will increase, RL min [ 50KW.
5
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
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.
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.
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
R
R
B
A
R
L
4
5
1
12
6
DCA1
DCA2
SA1 SA2
V
CC
10
2
3
9
Sine Wave
TC
SWO
Sine
Converter
Timing
Circuitry
C1
7
8
Triangle Wave
Square Wave
FMBI
FMSI
TWO
SQO
U1
S1
Square Wave
Converter
V
EE
XR-8038A
11
–15V
Figure 2. Generalized Test Circuit
Rev. 2.01
6
XR-8038A
V
CC
11
R
A
I
A
R
2
10K
Buffer
Buffer
7
8
4
10
SWITCH S
V
CC
R
1
C
40K
R
B
5
2I
B
11
EE
V
Figure 3. Detailed View of Current Sources I and 2I .
A
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
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:
resistors R and R separate (Figure 4.) R controls the
A
B
A
rising portion of the triangle and sine wave and the “low”
state of the square wave.
1
1
f +
+
R
t1 ) t2
5
3
B
·R Cǒ1 )
Ǔ
The magnitude of the triangle waveform is set at 1/3 V
;
CC
A
2R –R
A
B
therefore, the duration of the rising proportion of the
triangle is:
or, if R = R = R
A
B
2
3
0.3
RC
|
C· VCC- 3
1 VCC|
|
IA
|
C· DV
5
3
(
)
f +
for Figure 4.
t1 +
+
+
RA·C
V
CC
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:
2
3
|
31 VCC|
0.15
RC
· VCC-
C
|
|
RARBC
2RA-RB
C· DV
f +
5
3
t2 +
+
+
·
2V
V
2IB-IA
CC
CC
-
5R
5R
B
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 R = R
A
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,
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
R
B
A
R
4
5
1
12
6
L
V
CC
DCA1 DCA2 SA1 SA2
Sine Wave
10
2
3
9
TC
Sine
Timing
SWO
C1
Converter
Circuitry
Triangle Wave
Square Wave
7
8
FMBI
FMSI
TWO
SQO
U1
Square Wave
Converter
V
EE
XR-8038A
11
–15V
Figure 4. Possible Connection for External Duty Cycle Adjust
+15V
Frequency
Duty Cycle
12
4
5
1
6
R
L
DCA1 DCA2 SA1 SA2
V
CC
Sine Wave
10
2
3
9
TC
Timing
Sine
SWO
TWO
SQO
Circuitry
Converter
Triangle Wave
Square Wave
7
8
FMBI
FMSI
U1
Sine Wave
Converter
V
EE
XR-8038A
11
–15V
Figure 5. Single Potentiometer for External Duty Cycle Adjust
Rev. 2.01
8
XR-8038A
+15V
R
4
5
1
12
6
R
L
DCA1 DCA2
SA1 SA2
V
CC
Sine Wave
10
2
3
9
TC
Timing
Sine
SWO
TWO
SQO
Converter
Circuitry
C1
Triangle Wave
Square Wave
7
8
FMBI
FMSI
U1
Square Wave
Converter
V
EE
XR-8038A
11
–15V
Figure 6. No Duty Cycle Adjust
+15V
100K
100K
R
5
B
R
A
12
4
1
6
R
–15V
L
V
CC
DCA1 DCA2 SA1 SA2
Sine Wave
10
2
3
9
Timing
Sine
SWO
TC
C1
Circuitry
Converter
Triangle Wave
Square Wave
7
8
U1
TWO
SQO
FMBI
FMSI
Square Wave
Converter
V
EE
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
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
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
due to R can be calculated from:
A
The frequency of the waveform generator is an inverse
R1·VCC
R1 ) R2
VCC
5RA
1
RA
function of the dc voltage at pin 8 (measured from +V ).
CC
I +
·
+
(
)
By altering this voltage, frequency modulation is
performed.
A similar calculation holds for R .
B
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
R @C .
A
T
2. A 0.1mF capacitor is tied from pin 7 and 8 to ground.
NOTE:
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
-
This is only needed if the duty cycle is powered up with
RA >>RB.
SINGLE-SUPPLY AND SPLIT-SUPPLY OPERATION
(f=0 at V
=0). Care must be taken, however, to
SWEEP
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
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
to 2/3
CC
between +V and ground. A split power supply has the
V
CC
-2V.
CC
Rev. 2.01
10
XR-8038A
+15V
R
R
5
A
B
R
L
4
1
12
6
V
CC
DCA1 DCA2
SA1 SA2
Sine Wave
10
2
3
9
TC
Timing
C1
Sine
SWO
TWO
SQO
Circuitry
Converter
Triangle Wave
Square Wave
7
8
FMBI
FMSI
U1
Square Wave
Converter
FM
V
EE
XR-8038A
11
–15V
Figure 8. Frequency Modulator
+15V
R
4
R
5
A
B
R
L
1
12
6
DCA1 DCA2
SA1 SA2
V
CC
Sine Wave
10
2
3
9
Timing
C1
Sine
TC
SWO
Circuitry
Converter
Triangle Wave
Square Wave
7
8
FMBI
FMSI
U1
TWO
Square Wave
Converter
SQO
Sweep Voltage
- (V - 2)
V
V
EE
CC
SUP
< = V & < = V
IN
CC
XR-8038A
11
–15V
Figure 9. Frequency Sweep
Rev. 2.01
11
XR-8038A
20
15
1.03
1.02
1.01
-55°C
1.00
125°C
25°C
10
5
0.99
0.98
5
10
15
20
25
30
5
10
15
20
25
30
Supply Voltage
Supply Voltage
Figure 10. Power Dissipation
vs. Supply Voltage
Figure 11. Frequency Drift
vs. Power Supply
12
10
8
6
4
2
Unadjusted
Adjusted
0
10Hz
100Hz 1kHz
10kHz 100kHz 1MHz
Frequency
Figure 12. Sine Wave THD vs. Frequency
Rev. 2.01
12
XR-8038A
14 LEAD PLASTIC DUAL-IN-LINE
(300 MIL PDIP)
Rev. 1.00
8
7
14
1
E
1
E
D
A
2
A
L
Seating
Plane
C
A
α
1
B
e
A
e
B
B
e
1
INCHES
MILLIMETERS
SYMBOL
MIN
MAX
MIN
MAX
A
0.145
0.015
0.115
0.014
0.030
0.008
0.725
0.300
0.240
0.210
0.070
0.195
0.024
0.070
0.014
0.795
0.325
0.280
3.68
0.38
2.92
0.36
0.76
0.20
5.33
1.78
4.95
0.56
1.78
0.38
20.19
8.26
7.11
A
A
B
B
1
2
1
C
D
E
18.42
7.62
6.10
E
e
1
0.100 BSC
0.300 BSC
2.54 BSC
7.62 BSC
e
A
e
B
L
0.310
0.430
0.160
7.87
10.92
4.06
0.115
2.92
α
0°
15°
0°
15°
Note: The control dimension is the inch column
Rev. 2.01
13
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 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.
Rev. 2.01
16
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