SA575

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5

Expandor

The typical expandor configuration is shown in Figure 2.

The variable gain cell and the rectifier cell are in the signal

maximum headroom without clipping. The 0 dB ref is

eliminated, thus requiring only one external component,

so any offset voltage between Pins 4 and 9 will cause small

offset error current in the rectifier cell. This will affect the

accuracy of the gain cell. This can be improved by using an

extra capacitor from the input to Pin 4 and eliminating the

DC connection between Pins 4 and 9.

The expandor gain expression and the attack and release

time constant is given by Equation 1 and Equation 2,

respectively.

(eq. 1)

3.8 k

W x 100 mA

Expandor gain =

2

(eq. 2)

2.2

mF

10

mF

10

mF

VREF

S

EXP IN

EXP OUT

9, 11

4, 16

5, 15

7, 13

6, 14

8

Figure 2. Typical Expandor Configuration

10k

W

3.8k

W

10k

W