The information contained in this section has been developed through characterization by Intersil Semiconductor and is for use as

application and design information only. No guarantee is implied.

8-19

HA2546

input voltage range to match your needs. Referring to the

will notice the unusual design. The internal reference sets up

signal applied to this input will be forced across the scale

side of the differential pair. When the current through this

resistor reaches 1.2mA, all the current available is flowing in

the one side and full scale has been reached. Normally the

1.67k

Ω internal resistor sets the scale factor to 2V when the

Gain Adjust pins B and C are connected together, but you

may set this resistor to any convenient value using pins 16

(GA A) and 15 (GA C).

NC

NC

V-

V+

NC

NC

50

Ω

1K

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

Σ

REF

Y

X

Z

-

+

-

+

-

+

NC

NC

V-

V+

NC

NC

50

Ω

1K

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

Σ

REF

Y

X

Z

-

+

-

+

-

+

4.167K

FIGURE 3. AUTOMATIC GAIN CONTROL

In Figure 3, the HA-2546 is configured in a true Automatic

Gain Control or AGC application. The HA-5127, low noise op

amp, provides the gain control level to the X input. This level

will set the peak output voltage of the multiplier to match the

reference level. The feedback network around the HA-5127

provides stability and a response time adjustment for the

gain control circuit.

5k

Ω

10k

Ω

HA-5127

0.01

µF

10k

Ω

0.1

µF

1N914

3.3V

0.1

µF

+15V

20k

Ω

NC

NC

V-

V+

NC

NC

50

Ω

14

15

16

9

13

12

11

10

1

2

3

4

5

7

6

8

Σ

REF

Y

X

Z

-

+

-

+

-

+

-

+

Spec Number

511050-883