TPA2015D1

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SLOS638 – MAY 2010

GLOSSARY

The application section uses the following terms:

Limiter level

The maximum output voltage allowed before amplifier gain is automatically reduced.

SpeakerGuard™

TI's trademark name for the automatic gain control technology. It protects speakers by

limiting maximum output power.

Inflection point

The battery voltage threshold for reducing the limiter level. If the battery voltage drops

below the inflection point, the limiter level automatically reduces. Although it lowers the

maximum output power, it prevents high battery currents at end-of-charge low battery

voltages.

Battery track

The name for the continuous limiter level reduction at battery voltages below the inflection

point.

AGC

Automatic gain control.

VBAT

The battery supply voltage to the TPA2015D1. The VBAT pin is the input to the boost

converter.

Fixed-gain

The nominal audio gain as set by the GAIN pin. If the audio output voltage remains below

the limiter level, the amplifier gain will return to the fixed-gain.

Attack time

The rate of AGC gain decrease. The attack time is constant at 0.026 ms/dB.

Release time

The rate of AGC gain increase. The release time is constant at 1600 ms/dB.

SPEAKERGUARD™ THEORY OF OPERATION

SpeakerGuard™ protects speakers, improves loudness, and limits peak supply current. If the output audio signal

exceeds the limiter level, then SpeakerGuard™ decreases amplifier gain. The rate of gain decrease, the attack

time, is fixed at 0.026 ms/dB. SpeakerGuard™ increases the gain once the output audio signal is below the

limiter level. The rate of gain increase, the release time, is fixed at 1600 ms/dB. Figure 21 shows this

relationship.

Copyright © 2010, Texas Instruments Incorporated

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