MC1494P ONSEMI [ON Semiconductor], MC1494P Datasheet - Page 5

• Manufacturer Part Number: MC1494P
• Description: LINEAR FOUR-QUADRANT MULTIPLIER INTEGRATED CIRCUIT
• Manufacturer: ONSEMI [ON Semiconductor]

Introduction
operates on the principle of variable transconductance. It
features a single–ended current output referenced to ground
and provides two complementary regulated voltages for use
with the offset adjust circuits to virtually eliminate sensitivity
of the offset voltage nulls to changes in supply voltages.
proper and associated peripheral circuitry to provide these
features.
Regulator
essentially independent of supply variation. It also provides
two convenient regulated supply voltages which can be used
in the offset adjust circuitry. The regulated output voltage at
Pin 2 is approximately + 4.3 V, while the regulated voltage at
Pin 4 is approximately – 4.3 V. For optimum temperature
stability of these regulated voltages, it is recommended that
|I 2 | = |I 4 | = 1.0 mA (equivalent load of 8.6 k ). As will be
shown later, there will normally be two 20 k potentiometers
and one 50 k
and 4.
that controls all of the constant current sources in the MC1494.
Note that all current sources are related to current I 1 which is
determined by R1. For best temperatures performance, R1
should be 16 k so that I 1
Multiplier
Figure 17) is nearly identical to the MC1495 and is discussed
in detail in Application Note AN489, Analysis and Basic
Operation of the MC1495 . The result of this analysis is that
the differential output current of the multiplier is given by:
Therefore, the output is proportional to the product of the two
input voltages.
MOTOROLA ANALOG IC DEVICE DATA
The MC1494 is a monolithic, four–quadrant multiplier that
The regulator biases the entire MC1494 circuit making it
The multiplier section of the MC1494 (center section of
As shown in Figure 17, the MC1494 consists of a multiplier
The regulator also establishes a constant current reference
20
10
0
Figure 15. Large Signal Voltage versus Frequency
100
I A – I B = I
potentiometer connected between Pins 2
1.0 k
f, FREQUENCY (Hz)
1
2
0.5 mA for all applications.
[
With MC1456 Buffer Op Amp
No Op Amp, R L = 47 k
2V X V Y
R X R Y I 1
10 k
2
1
CIRCUIT DESCRIPTION
100 k
MC1494
Differential Current Converter
current (I A –I B ) of the multiplier to a single–ended output
current (I O ); I O = I A – I B
voltage by placing a load resistor R L from the output (Pin 14)
to ground (Figure 19) or by using an op amp as a
current–to–voltage converter (Figure 18). The result in both
circuits is that the output voltage is given by:
DC OPERATION
Selection of External Components
recommended. For this circuit, R X = 30 k , R Y = 62 k ,
R1 = 16 k
scale factor (K) equal to 1/10, the value of R L can be
calculated to be:
achieved by making R L a fixed 47 k resistor. However, if it is
desired that the scale factor be exact, R L can be comprised of
a fixed resistor and a potentiometer as shown in Figure 18.
where, K (scale factor) =
This portion of the circuitry converts the differential output
The output current can be easily converted to an output
For low frequency operation the circuit of Figure 18 is
Thus, a reasonable accuracy in scale factor can be
0.108
0.106
0.104
0.102
0.098
0.096
0.094
0.1
– 55
Figure 16. Scale Factor (K) versus Temperature
or R L =
– 35 –15
K =
R L = 46.5 k
and, hence, I 1
or
V O =
10
1
(2) (10)
R X R Y I 1
I O =
=
5.0
T A , AMBIENT TEMPERATURE ( C)
2R L V X V Y
R X R Y I 1
R X R Y I 1
2R L
2V X V Y
R X R Y I 1
=
25
R X R Y I 1
(30 k) (62 k) (0.5 mA)
2R L
0.5 mA. Therefore, to set the
K Factor Adjusted for 1/10 at 25 C)
45
= KV X V Y
65
20
85
105
125
5
145