®

MPY534

6

Internal device tolerances make this relationship accurate to

within approximately 25%. Some applications can benefit

from reduction of the SF by this technique. The reduced

input bias current and drift achieved by this technique can be

likened to operating the input circuitry in a higher gain, thus

reducing output contributions to these effects. Adjustment

of the scale factor does not affect bandwidth.

The MPY534 is fully characterized at V

±15V, but

operation is possible down to

±8V with an attendant reduc-

tion of input and output range capability. Operation at

voltages greater than

±15V allows greater output swing to

be achieved by using an output feedback attenuator (Figure

2).

BASIC MULTIPLIER CONNECTION

Figure 1 shows the basic connection as a multiplier. Accu-

racy is fully specified without any additional user trimming

circuitry. Some applications can benefit from trimming one

or more of the inputs. The fully differential inputs facilitate

referencing the input quantities to the source voltage com-

mon terminal for maximum accuracy. They also allow use

of simple offset voltage trimming circuitry as shown on the

X input.

The differential Z input allows an offset to be summed in

V

output voltage reference and should be connected to the

ground reference of the driven system for maximum accu-

racy.

A method of changing (lowering) SF by connecting to the

SF pin was discussed previously. Figure 2 shows another

method of changing the effective SF of the overall circuit

using an attenuator in the feedback connection to Z

method puts the output amplifier in a higher gain and is thus

accompanied by a reduction in bandwidth and an increase in

output offset voltage. The larger output offset may be

reduced by applying a trimming voltage to the high imped-

ance input Z

The flexibility of the differential Z inputs allows direct

conversion of the output quantity to a current. Figure 3

shows the output voltage differentially-sensed across a se-

ries resistor forcing an output-controlled current. Addition

of a capacitor load then creates a time integration function

useful in a variety of applications such as power computa-

tion.

SQUARER CIRCUIT

Squarer operation is achieved by paralleling the X and Y

inputs of the standard multiplier circuit. Inverted output can

be achieved by reversing the differential input terminals of

either the X or Y input. Accuracy in the squaring mode is

typically a factor of two better than the specified multiplier

mode with maximum error occurring with small (less than

1V) inputs. Better accuracy can be achieved for small input

voltage levels by using a reduced SF value.

MPY534

X

1

+V

S

X

2

Out

SF

Z

1

Y

1

Z

2

Y

2

–V

S

–15V

+15V

Y Input

±10V FS

±12V PK

X Input

±10V FS

±12V PK

470k

Ω

Optional

Summing

Input,

Z, ±10V PK

V

=

+ Z

2

(X

10V

50k

Ω

+15V

–15V

1k

Ω

Optional Offset

Trim Circuit

MPY534

X

1

+V

S

X

2

Out

SF

Z

1

Y

1

Z

2

Y

2

–V

S

10k

Ω

–15V

+15V

Y Input

±10V FS

±12V PK

X Input

±10V FS

±12V PK

90k

Ω

V

= (X

(Scale = 1V)

Optional

Peaking

Capacitor

C

MPY534

X

1

+V

S

X

2

Out

SF

Z

1

Y

1

Z

2

Y

2

–V

S

–15V

+15V

Y Input

±10V FS

±12V PK

X Input

±10V FS

±12V PK

Current

Sensing

Resistor,

R

min

Integrator

Capacitor

(see text)

I

x

(X

10V

1

R

S

FIGURE 3. Conversion of Output to Current.

FIGURE 1. Basic Multiplier Connection.

FIGURE 2. Connections for Scale-Factor of Unity.

DIVIDER CIRCUIT

The MPY534 can be configured as a divider as shown in

Figure 4. High impedance differential inputs for the numera-

tor and denominator are achieved at the Z and X inputs,

respectively. Feedback is applied to the Y

be summed directly into V

tion is made to a multiplying input, the effective gain of the

output op amp varies as a function of the denominator input

voltage. Therefore, the bandwidth of the divider function is

proportional to the denominator voltage (see Typical Perfor-

mance Curves).