EXAR XR

XR-8038A
May 1994-4
Precision Waveform Generator
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 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. It can be
readily interfaced with a monolithic phase-detector circuit,
such as the XR-2228 to form stable phase-locked circuits.
PIN ASSIGNMENT
1
14
NC
2
13
NC
3
12
SINE ADJ
4
11
–V OR GND
5
10
TIMING
CAPACITOR
+VCC
6
9
FM BIAS
7
8
SINE ADJ
~
DUTY CYCLE
ADJ
XR-8038A
FM SWEEP
INPUT
ORDERING INFORMATION
Part Number
XR-8038AM
XR-8038AN
XR-8038AP
XR-8038ACN
XR-8038ACP
Package
Ceramic
Ceramic
Plastic
Ceramic
Plastic
Operating Temperature
–55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
SYSTEM DESCRIPTION
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
The XR-8038A precision waveform generator produces
highly stable and sweepable square, triangle, and sine
waves across eight frequency decades. The XR-8038A
is an advanced version of the XR-8038, with improved
sine distortion temperature drift. 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 100kΩ
potentiometer between the supplies, with the wiper connected to Pin 1.
ABSOLUTE MAXIMUM RATINGS
Power Supply
36V
Power Dissipation (package limitation)
Ceramic Package
750mW
Derate Above +25°C
6.0mW/°C
Plastic Package
625mW
Derate Above +25°C
5mW/°C
Storage Temperature Range
–65°C to +150°C
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.
XR-8038A
ELECTRICAL CHARACTERISTICS
Test Conditions: VS = ±5V to ±15V, TA = 25°C, RL = 1MΩ, RA = RB = 10kΩ, C1 = 3300pF, S1 closed, unless
otherwise specified.
8038AM/8038A
PARAMETERS
MIN
8038AC
TYP
MAX
MIN
10
±5
12
30
±15
15
TYP
MAX
UNITS
12
30
±15
20
V
V
mA
CONDITIONS
GENERAL CHARACTERISTICS
Supply Voltage, VS
Single Supply
Dual Supplies
Supply Current
10
±5
VS = ±10V (Note 1)
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
Temperature Stability
XR-8038AM
XR-8038A
XR-8038AC
Power Supply Stability
200
KHz
0.001
0.001
Hz
100
1000:1
0.1
100
1000:1
0.2
kHz
0.5
1000
50
50
1000
%
kΩ
S1 Open (Notes 2 & 3)
S1 Open (Note 3)
Values of RA and RB
—
ppm/°C
TA = –55°C to +125°C
50
0.05
ppm/°C
%/V
TA = 0°C to +70°C
(Note 4)
0.98
0.2
100
40
x VSPLY
V
nsec
nsec
%
0.5
—
RA = RB, = 1.5kΩ, C1 = 680pF
RL = 10K
RA = RB = 1MΩ, C1= 500µF
(Low Leakage Capacitor)
—
100
0.05
OUTPUT CHARACTERISTICS
Square-Wave
Amplitude (Peak-to-Peak)
Saturation Voltage
Rise Time
Fall Time
Duty Cycle Adjustment
Triangle/Sawtooth/Ramp
Amplitude (Peak-to-Peak)
Linearity
Output Impedance
Sine-Wave Amplitude (Peak-to-Peak)
Distortion
Unadjusted
Adjusted
∆THD/∆T
0.9
0.98
0.2
100
40
2
0.3
0.2
0.9
0.4
98
0.33
0.05
200
0.22
0.7
0.5
0.5
2
0.3
0.2
1.5
Note 1: Currents through RA and RB not included.
Note 2: VSUPPLY = 20V.
Note 3: Apply sweep voltage at Pin 8.
VCC – (1/3 VSUPPLY – 2) ≤ VPIN 8 ≤ VCC
VSUPPLY = Total Supply Voltage across the IC
Note 4: 10V ≤ VS ≤ 30V or ±5V ≤ VS ≤ 15V.
Note 5: Pin 12 open circuited (No. 82kΩ resistor as standard 8038).
Note 6: Triangle duty cycle set at 50%, use RA and RB.
Note 7: As RL is decreased distortion will increase, RL min ≈ 50kΩ.
2
0.5
98
0.33
0.1
200
0.22
0.8
0.5
0.3
3
x VSPLY
%
Ω
x VSPLY
%
%
%
Measured at Pin 9
RL = 100kΩ
Isink = 2mA
RL = 4.7kΩ
RL = 4.7kΩ
Measured at Pin 3.
RL = 100kΩ
IOUT = 5mA
RL = 100kΩ
RL = 1MΩ (Notes 5, 6 & 7)
RL = 1MΩ (Notes 5, 6 & 7)
XR-8038A
Notes
3
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 herein 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 1986 EXAR Corporation
Data Sheet June 1994
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
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