TAS2120 datasheet(33/113 Pages) TI2

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6.4.2.3 Class-D Amplifier

TAS2120 has integrated high performance class-D amplifier with low idle channel noise, low distortion and high

PSRR. The Class-D amplifier switches on a clock frequency derived from the SBCLK frequency and is always

synchronized to the input clock source. The SAMP_RATE_CFG register enables selection between input clock

source based out of multiple of 44.1kHz vs 48kHz multiples.

Table 6-22. Sample rate configuration

SAMP_RATE_CFG

Configuration

0 (default)

Audio data rate is multiple/sub-

multiple of 48ksps

Audio data rate is multiple/sub-

multiple of 44.1ksps

For improvements in EMI performance the class-D amplifier supports programmable Edge rate control (ERC)

and class-D clock spread spectrum modulation (SSM).

The edge rate of class-D can be controlled using CLASSD_OUTPUT_EDGERATE_CTRL[1:0] register. By

default the class-D output edge rate is configured to fastest setting to enable high efficiency in the system.

The class-D output edge rate can be slowed down using other configuration settings to reduce the EMI energy

at high frequency with reduction in efficiency. The exact rate of change of output edge rate varies based on

output load conditions, and the values mentioned in the tables below are approximate edge rate levels for default

loading conditions.

Table 6-23. Class-D output edge rate control

CLASSD_OUTPUT_EDGERATE

_CTRL[1:0]

Configuration

Class-D output edge rate of 0.5

V/ns

Class-D output edge rate of 1.0

V/ns

Reserved

11(default)

Class-D output edge rate of 2

V/ns

The class-D amplifier has over current protection on each of the output power FETs, including the PVDD High

side, VDD high side and the ground power FETs.

The class-D amplifier output impedance can be controlled when the outputs stop switching during Noise gate

mode using CLASSD_HIZ_MODE control register.

Table 6-24. Class-D high-Z mode control

CLASSD_HIZ_MODE

Configuration

0 (default)

Output pulled down with 2.5kΩ

Output pulled down with >13kΩ

6.4.2.4 Supply Tracking Limiters with Brown Out Prevention

TAS2120 monitors class-D supply voltage along with the audio signal to automatically decrease gain when the

audio signal peaks exceed a programmable threshold. This helps prevent clipping and extends playback time

through end of charge battery conditions. The limiter and brown out module calculates the signal attenuation

required based on the condition of the signal level, channel gain and the selected supply voltage.

www.ti.com

TAS2120

SLASFC6A – AUGUST 2024 – REVISED AUGUST 2025

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