Datasheet

LM49350, LM49350RLEVAL

SNAS359D –SEPTEMBER 2008–REVISED JUNE 2012

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Digital Effects Engine

DIGITAL SIGNAL PROCESSOR (DSP)

The LM49350 is designed to handle the entire audio signal conditioning and processing within the audio system,

thereby freeing up the workload of any other applications processor contained within the system. The LM49350

features two independent DSPs, one for the DAC and the other for the ADC. Each DSP is fully featured and

performs as a professional quality digital audio effects engine. The data paths on each DSP engine are 24 bits

wide for ultimate flexibility. Both DSP engines feature digital volume control, automatic level control (ALC), digital

soft clip compression, and a 5-band parametric EQ. The ADC DSP engine adds a dedicated high-pass filter to

reduce wind noise or pop noise during uplink. The DAC DSP engine adds a digital 3D algorithm that allows for

stereo widening of the original audio signal. The effects chain of each DSP engine is shown by the diagrams

below.

Figure 63. ADC DSP Effects Chain

Figure 64. DAC DSP Effects Chain

The ADC and DAC DSP engines can be cascaded together in any order via the digital mixer to combine different

audio effects to the same signal path. For example, a signal can be processed with high-pass filtering from the

ADC effects engine with 3D stereo widening from the DAC effects engine. The 5-band parametric EQs from each

DSP engine can be combined to form a single 10-band parametric EQ or a single 5-band parametric EQ with

±30dB (instead of ±15dB) gain control for each band.

Table 46. ADC EFFECTS (0x70h)

Bits Field Description

0 ADC_HPF_ENB This enables the ADC's High Pass Filter.

1 ADC_ALC_ENB This enables the ADC's Auto Level Control.

2 ADC_PK_ENB This enables the ADC's Peak Detector.

3 ADC_EQ_ENB This enables the ADC's 5-band Parametric EQ.

4 ADC_SCLP_ENB This enables the ADC's Soft Clip Feature.

Product Folder Links: LM49350 LM49350RLEVAL