Cirrus Logic CRD44800-ST-FB - Manual

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Copyright © Cirrus Logic, Inc. 2004
(All Rights Reserved)
Cirrus Logic, Inc.
www.cirrus.com
CRD44800-ST-FB
60 W Full-Bridge Reference Design for the CS44800
Features
Eight full-bridge channels, 60 W each
Programmable load compensation
Power Supply Rejection (PSR) feedback
allowing amplifier to operate from low cost
linear unregulated power supplies
Peak signal limiting
Thermal and over-current protection
> 85% amplifier efficiency
Works with GUI to configure the board or in a
standalone mode for easy operation.
Demonstrates recommended layout and
grounding arrangements
Description
The CRD44800-ST-FB PWM Amplifier demonstrates
the CS44800, Cirrus’ eight-channel pure digital PMW
controller. This reference design implements an eight-
channel amplifier which delivers 60 W per full-bridge
channel into 8
Ω loads using a single +30 V supply (at
10% THD+N). A 155 W Switched Mode Power Supply
(SMPS) is used to power the CRD44800-ST-FB.
As shown below, the CS44800 IC takes four stereo dig-
ital audio inputs in I²S format and converts them to PWM
outputs. This 64-pin LQFP IC provides an integrated
sample rate converter for 32 kHz-192 kHz input sample
rate support, volume up/down, speaker load compensa-
tion, peak limiting to prevent amplifier clipping, power
supply ripple compensation, and AM frequency interfer-
ence elimination.
This reference design uses the the ST Micro STA500, an
integrated power stage back end for digital amplifiers
(four STA500 parts configured as full-bridges are used
for this eight-channel design). Current limiting and ther-
mal protection are provided by the STA500.
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
CRD44800-ST-FB Reference Design
I
ST Micro
STA500A
CS44800
(PWM Controller)
LPF
8
Ω
8
Ω
Channels 1 and 2 (of 8)
To channels 3/4
To channels 5/6
To channels 7/8
PWM Outputs
+30V
CS4461 ADC
+30V
PSR Circuitry
Audio Driver Board
I 2 S Clocks & Data
I 2 C Host Control
155W Switched Mode
Power Supply
+30V/+5V
LPF
DEC ‘04
DS632ARD1