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© Semiconductor Components Industries, LLC, 2016
December, 2016 − Rev. 2
1 Publication Order Number:
AND9465/D
AND9465/D
Class D Amplifiers
of LC823450 Series
for Audio Applications
Introduction
This application note describes Class D Amplifiers (called
D−AMP hereafter) guideline to enable customers to control
D−AMP correctly in their application.
Intended audience is customers who are building audio
application using LC823450 Series (called LC823450
hereafter).
Background
D−AMP Structure
LC823450 has two D−AMP for L channel and R channel
internally. D−AMP is composed of DAC and AMP. DAC is
mainly composed of Interpolator, Delta-Sigma Modulator
and PWM Generator as shown in Figure 1.
Regarding the DAC part, Interpolator is a 8times
interpolator which converts sampling frequency (Fs) up to
8 Fs by digital filter. Delta-Sigma Modulator at first
converts input data up to 3times oversampling by sample &
hold logic, and it does delta-sigma modulation. Delta-Sigma
Modulator also has 9 levels or 17 levels for quantization, and
it is processed with timing based on 24 Fs. PWM Generator
generates a PWM signal with 1 bit width based on
Delta-Sigma Modulator output and its period is 1/24 Fs.
The AMP part is a dedicated I/O buffer for D−AMP and
it has an impedance control function to be used while it is
turning on or off.
Figure 1. D−AMP Block Diagram
AMP
DAC
D−AMP
PWM
Generator
DS
Modulator
Interpolator
LOUT/
ROUT
Figure 2. PWM Generation
(1)
(2)
(3)
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APPLICATION NOTE
