V

-dBV

IN

TPA2029D1

SLOS661A – DECEMBER 2011 – REVISED APRIL 2012

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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 16. 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 TPA2029D1 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

AGC Parameters

TPA2029D1

Attack Time

14.084 ms / 6 dB step

Release Time

822 ms/ 6 dB step

Hold Time

off

Fixed Gain

9 dB

NoiseGate Threshold

4 mV

Output Limiter Level

9 dBV

Max Gain

30 dB

Compression Ratio

2:1

10

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