1 dB

20 Ps

0.5 dB

1 dB

0.5 dB

Release

Vin decreases

Adjusting

Vin increases

Attack

Attack

Vin increases

800 ms

0

1

2

3

4

5

6

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

Supply Voltage (V)

64.9 k:

20 k:

LM48512

SNAS497A – OCTOBER 2010 – REVISED APRIL 2012

www.ti.com

sets the output swing as shown in Figure 4.

Figure 4. AGC Output Swing vs Supply Voltage Graph

accordingly.

See Figure 5 for the following:

Attack: AGC attack occurs at increments of -1dB steps every 20

μs until the output is below the output swing

limit or when it reaches the maximum gain compression of -6dB.

Release: AGC releases at increments of 0.5dB steps per every 800ms if the output does not reach the output

swing limit.

Adjusting: While the part is in compression mode, the first attack following a release is at increments of 0.5dB

steps, this is also referred to as Adjusting.

Figure 5. AGC Operation

Automatic Level Control

The ALC circuitry is similar to AGC in that it also limits the output swing of the amplifier, but the difference is that

limited to 90% of PVOUT, with the same Attack, Release, and Adjusting characteristics as the AGC.

12

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