V

-dBV

IN

MaxGain

= 22dB

MaxGain

= 30dB

TPA2016D2

Figure 28. Output Signal vs. Input Signal State Diagram Showing Different Maximum Gains

A particular application requiring maximum gain of 22dB, for example. Thus, set the maximum gain at 22dB. The

amplifier gain will never have a gain higher than 22dB; however, this will reduce the limiter range.

Attack, Release, and Hold time:

• The attack time is the minimum time between gain decreases.

• The release time is the minimum time between gain increases.

• The hold time is the minimum time between a gain decrease (attack) and a gain increase (release). The hold

time can be deactivated. Hold time is only valid if greater than release time.

Successive gain decreases are never faster than the attack time. Successive gain increases are never faster

than the release time.

All time variables (attack, release and hold) start counting after each gain change performed by the AGC. The

AGC is allowed to decrease the gain (attack) only after the attack time finishes. The AGC is allowed to increase

the gain (release) only after the release time finishes counting. However, if the preceding gain change was an

attack (gain increase) and the hold time is enabled and longer than the release time, then the gain is only

increased after the hold time.

The hold time is only enabled after a gain decrease (attack). The hold time replaces the release time after a gain

decrease (attack). If the gain needs to be increased further, then the release time is used. The release time is

used instead of the hold time if the hold time is disabled.

The attack time should be at least 100 times shorter than the release and hold time. The hold time should be the

same or greater than the release time. It is important to select reasonable values for those variables in order to

prevent the gain from changing too often or too slow.

Figure 29 illustrates the relationship between the three time variables.

Copyright © 2008, Texas Instruments Incorporated

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