Cirrus Logic CRD44600-PH-FB - Manual

1
Copyright © Cirrus Logic, Inc. 2005
(All Rights Reserved)
Cirrus Logic, Inc.
www.cirrus.com
CRD44600-PH-FB
Stereo 100 W PWM Amplifier Reference Design
Features
z Two full-bridge channels, 100 W each
z 106 dB Dynamic Range - both channels
z 0.015% THD+N at 1 W
z Power Supply Rejection (PSR) feedback
allowing amplifier to operate from low cost
linear unregulated power supplies
z Spread Spectrum Modulation - Reduces
Modulation Energy
z Passes CISPR and FCC requirements for
radiated and power line conducted
emissions
z Independent peak signal limiting per channel
z Thermal and over-current protection
z > 85% amplifier efficiency
z Works with GUI to configure the board
z Demonstrates recommended layout and
grounding arrangements
Description
The CRD44600-PH-FB PWM Amplifier demonstrates
the CS44600, Cirrus’ multi-channel pure digital PWM
controller. This reference design implements a two-
channel amplifier which delivers 100 W per full-bridge
channel into 8
Ω loads using a single +50 V supply (at
1% THD+N). A 155 W unregulated linear power supply
is used to power the CRD44600-PH-FB.
As shown below, the CS44600 IC takes two stereo digi-
tal audio PCM inputs and converts them to PWM
outputs. This 64-pin LQFP PWM controller provides an
integrated sample rate converter for 32 kHz-192 kHz in-
put sample rate support, volume up/down, speaker load
compensation, peak limiting to prevent amplifier clipping,
power supply ripple compensation, and AM frequency
interference elimination.
This reference design uses the the Philips TDA8939, an
integrated power stage back end for digital amplifiers
(two TDA8939 parts configured as full-bridges are used
for this two-channel design). Current limiting and ther-
mal protection are provided by the TDA8939.
The inductor/capacitor 2
nd
order low pass filter (LPF) re-
moves high frequency components from the output
signal effectively converting it from digital to analog.
ORDERING INFORMATION
CRD44600-PH-FB Reference Design
I
Philips
TDA8939
CS44600
(PWM Controller)
LPF
Channel 1
+50 V
CS4461 ADC
+50 V
PSR Circuitry
Audio Inputs and GUI
Interface
155W Unregulated
Linear Power Supply
Philips
TDA8939
LPF
+50 V
Channel 2
+50 V
PCM Clocks & Data
I 2 C Host Control
8
Ω
8
Ω
MAR '05
DS633RD1