MAX038EPP MAXIM [Maxim Integrated Products], MAX038EPP Datasheet - Page 8

• Manufacturer Part Number: MAX038EPP
• Description: High-Frequency Waveform Generator
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX038 is a high-frequency function generator
that produces low-distortion sine, triangle, sawtooth, or
square (pulse) waveforms at frequencies from less than
1Hz to 20MHz or more, using a minimum of external
components. Frequency and duty cycle can be inde-
pendently controlled by programming the current, volt-
age, or resistance. The desired output waveform is
selected under logic control by setting the appropriate
code at the A0 and A1 inputs. A SYNC output and
phase detector are included to simplify designs requir-
ing tracking to an external signal source.
The MAX038 operates with ±5V ±5% power supplies.
The basic oscillator is a relaxation type that operates by
alternately charging and discharging a capacitor, C
High-Frequency Waveform Generator
Figure 1. Block Diagram and Basic Operating Circuit
8
_______________Detailed Description
+5V
-5V
_______________________________________________________________________________________
R
F
*
*
C
R
F
D
= SIGNAL DIRECTION, NOT POLARITY
= BYPASS CAPACITORS ARE 1 F CERAMIC OR 1 F ELECTROLYTIC IN PARALLEL WITH 1nF CERAMIC.
R
2, 9, 11, 18
IN
20
10
17
5
6
8
7
1
DADJ
GND
FADJ
IIN
V+
V-
GND
COSC
REF
OSCILLATOR
OSCILLATOR
GENERATOR
REFERENCE
CURRENT
VOLTAGE
2.5V
-250 A
TRIANGLE
OSC A
OSC B
F
,
COMPARATOR
COMPARATOR
with constant currents, simultaneously producing a tri-
angle wave and a square wave (Figure 1). The charg-
ing and discharging currents are controlled by the cur-
rent flowing into IIN, and are modulated by the voltages
applied to FADJ and DADJ. The current into IIN can be
varied from 2µA to 750µA, producing more than two
decades of frequency for any value of C
±2.4V to FADJ changes the nominal frequency (with
V
fine control.
Duty cycle (the percentage of time that the output wave-
form is positive) can be controlled from 10% to 90% by
applying ±2.3V to DADJ. This voltage changes the C
charging and discharging current ratio while maintaining
nearly constant frequency.
DETECTOR
SHAPER
PHASE
FADJ
SINE
TRIANGLE
SQUARE
= 0V) by ±70%; this procedure can be used for
DGND
15
SINE
A0
*
3
+5V
MUX
DV+
16
MAX038
4
A1
SYNC
PDO
OUT
PDI
19
14
12
13
R
L
F
. Applying
C
L
F