XR-8038A Datasheet, PDF (1/4 Pages) Exar Corporation – Precision Waveform Generator

Precision Waveform Generator
XR-8038A
May 1994-4
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 exter-
nal 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 fre-
quency, 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 volt-
age 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 simul-
taneously 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.
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
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
PIN ASSIGNMENT
SINE ADJ 1
~²
3
DUTY CYCLE ⁴
ADJ
5
+V_{CC 6}
FM BIAS ₇
XR-8038A
14 ^NC
13 ^NC
12 ^{SINE ADJ}
11 ^{–V OR GND}
10
TIMING
CAPACITOR
9
8
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
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 em-
ploys 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 con-
nected to Pin 1.
Small frequency deviation (FM) is accomplished by ap-
plying modulation voltage to Pins 7 and 8; large frequency
deviation (sweeping) is accomplished by applying volt-
age 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 volt-
age. Triangle output amplitude is typically 1/3 of the
supply, and sine wave output reaches 0.22 of the supply
voltage.