7.3 Feature Description

7.3.1 Analog Gain

The analog gain of the TPA3139D2 can be changed by GAIN_SEL pin. Low Level, Gain = 20 dB; High Level,

Gain = 26 dB.

7.3.2 SD/ FAULT and MUTE Operation

The TPA3139D2 device employs a shutdown mode of operation designed to reduce supply current (ICC) to the

absolute minimum level during periods of nonuse for power conservation. The SD/ FAULT input pin should be

held high (see Section 6 table for trip point) during normal operation when the amplifier is in use. Pulling SD/

FAULT low causes the outputs to mute and the amplifier to enter a low-current state. Never leave SD/ FAULT

unconnected, because the amplifier operation would be unpredictable.

For the best power-off pop performance, place the amplifier in the shutdown or mute mode prior to removing the

power supply voltage.

For some single ended input application case, suggest to mute the device first then release SD/ FAULT, then

umute the output. This sequence power-up sequence with best pop performance.

7.3.3 PLIMIT

If selected, the PLIMIT operation limits the output voltage to a level below the supply rail. If the amplifier operates

like it is powered by a lower supply voltage, then it limits the output power by voltage clipping. Add a resistor

divider from GVDD to ground to set the threshold voltage at the PLIMIT pin.

Figure 7-1. PLIMIT Circuit Operation

The PLIMIT circuit sets a limit on the output peak-to-peak voltage. The limiting is done by limiting the duty cycle

to a fixed maximum value. The limit can be thought of as a "virtual" voltage rail which is lower than the supply

connected to PVCC. The "virtual" rail is approximately 5.7 times (with BD mode) and 11.4 times (with 1SPW

mode) the voltage at the PLIMIT pin. The output voltage can be used to calculate the maximum output power for

a given maximum input voltage and speaker impedance.

2

L

P

L

S

OUT

L

R

V

R + 2

R

P

=

for unclipped power

2

R

æ

ö

æ

ö

´

ç

÷

ç

÷

ç

÷

´

è

ø

è

ø

´

(1)

where

• POUT (10%THD) = 1.25 × POUT (unclipped)

• RL is the load resistance.

• RS is the total series resistance including RDS(on), and output filter resistance.

• VP is the peak amplitude, which is limited by "virtual" voltage rail.

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TPA3139D2

SLOS810A – OCTOBER 2019 – REVISED AUGUST 2020

Copyright © 2020 Texas Instruments Incorporated

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