V

-dBV

IN

TPA2017D2

Since the number of gain steps is limited the compression region is limited as well. The following figure shows

how the gain changes vs. the input signal amplitude in the compression region.

Figure 20. Input Signal Voltage vs Gain

Thus the AGC performs a mapping of the input signal vs. the output signal amplitude.

Pins AGC1 and AGC 2 are used to enable/disable the limiter, compression, and noise gate function. Table 1

shows each function.

Table 1. FUNCTION DEFINITION FOR AGC1 AND AGC2

AGC1

AGC2

Function

0

0

AGC Function disabled

0

1

AGC Limiter Function enabled

1

0

AGC, Limiter, and Compression Functions enabled

1

1

AGC, Limiter, Compression, and Noise Gate Functions enabled

The default values for the TPA2017D2 AGC function are given in Table 2. The default values can be changed at

the factory during production. Refer to the TI representative for assistance with different default value requests.

Table 2. AGC DEFAULT VALUES

Attack Time

6.4 ms / step

Release Time

1.81 sec/step

Fixed Gain

6 dB

NoiseGate Threshold

20 mV

Output Limiter Level

9 dBV

Max Gain

30 dB

Compression Ratio

2:1

Copyright © 2009, Texas Instruments Incorporated

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Product Folder Link(s): TPA2017D2