Cirrus-logic CRD44800 Manual do Utilizador descarregar pdf

Cirrus Logic, Inc.

www.cirrus.com

CRD44800

50 W Half-Bridge Reference Design for the CS44800

Features

Eight half-bridge channels, 50 W each

Least amount of discrete components per

channel

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 PWM Amplifier demonstrates the

CS44800, Cirrus’ eight-channel pure digital PMW con-

troller. This reference design implements an eight-

channel amplifier which delivers 50 W per half-bridge

channel into 6 Ω loads using a single +45 V supply (at

10% THD+N). A 155 W Switched Mode Power Supply

(SMPS) is used to power the CRD44800.

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, PopGuard® to prevent pops in single voltage rail

half-bridge applications, peak limiting to prevent amplifi-

er 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

(four TDA8939 parts configured as half-bridges are used

for this eight-channel design). Current limiting and ther-

mal protection are provided by the TDA8939.

The inductor/capacitor 2

order low pass filter (LPF) re-

moves high frequency components from the output

signal effectively converting it from digital to analog.

ORDERING INFORMATION

CRD44800 Reference Design

Philips

TDA8939

CS44800

(PWM Controller)

LPF

6Ω

Channels 1 and 2 (of 8)

To channels 3/4

To channels 5/6

To channels 7/8

PWM Outputs

+45V

CS4461 ADC

+45V

PSR Circuitry

Audio Driver Board

S Clocks & Data

C Host Control

155W Switched Mode

Power Supply

+45V/+5V

DEC ‘04

DS632RD2

1 2 3 4 5 6 ... 28 29

CRD44800 1

Resumo do Conteúdo

Página 1 - CRD44800

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CRD4480010System Issues2.1 Power Supply RatingsThe required power supply current rating can be estimated as follows. 33 W is used as thereference outp

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CRD44800112.3 Electromagnetic Interference (EMI)The EMI challenges that face a maker of Class-D amplifiers are largely the same challengesthat have be

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CRD4480012than about 25 mm.It is extremely critical that the layout of the power amplifier section of the Cirrus LogicCS44800 Reference Design be copi

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CRD44800133. SCHEMATICS Figure 4. Power and Connectors

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CRD4480014Figure 5. CS44800

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CRD4480015 Figure 6. Left/Right Back Surround Channels

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CRD4480016Figure 7. Left/Right Surround Channels

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CRD4480017 Figure 8. LFE/Center Channels

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CRD4480018 Figure 9. Left/Right Channels

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CRD4480019Figure 10. PSR Feedback

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CRD448002TABLE OF CONTENTS1. SCHEMATIC DESCRIPTIONS ...

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CRD44800204. LAYOUTFigure 11. Silk Screen Top

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CRD4480021Figure 12. Topside Layer

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CRD4480022Figure 13. Bottomside Layer

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CRD44800235. BILL OF MATERIALS Line ItemRev Description Qty U/M Reference Designator MFG MFG. P/N1 A CAP 1000pF ±10% 50V X7R 0603 2 EA C145 C

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CRD4480024Line ItemRev Description Qty U/M Reference Designator MFG MFG. P/N21 A IND, 22UH, 3.5A 8 EA L5 L6 L7 L8 L9 L10 L11 L12 TRANSTEK MAGNETIC

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CRD44800256. TYPICAL PERFORMANCE PLOTS -5+1-4.5-4-3.5-3-2.5-2-1.5-1-0.5-0+0.5dBr A20 20k50 100 200 500 1k 2k 5k 10kHzFigure 16. Frequency

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CRD44800260.00110.0020.0050.010.020.050.10.20.5%20 20k50 100 200 500 1k 2k 5k 10kHz1 W10 W20 WFigure 17. THD+N vs. Frequency at 1 W, 10 W, and 20 W

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CRD44800270.01100.020.050.10.20.5125%100m 50200m 500m 1 2 5 10 20WFigure 18. THD+N vs. Power at 1 kHz

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CRD4480028-140+0-130-120-110-100-90-80-70-60-50-40-30-20-10dBr A20 20k50 100 200 500 1k 2k 5k 10kHzFigure 19. FFT at -60 dBFS and 1 kHz

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CRD44800297. REVISION HISTORY Release Date ChangesRD1 June 2004 1st ReleaseRD2 December 2004 2nd Release-Updated schematics and layout to reflec

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CRD4480031. SCHEMATIC DESCRIPTIONS 1.1 CRD44800 PWM AmplifierThe CS44800 shown in Figure 5 employs a built-in Sample Rate Converter (SRC) to supportal

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CRD448004In the Remote mode, the DB-9 connector (J14, labelled RS-232) is connected to a host PC.All aspects of the CS44800 may then be evaluated usin

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CRD4480052. OPERATION INFORMATIONSwitches and Indicators (Located on the Driver Board):RESET Pushbutton (S1) - forces a complete system reset.MUTE Pus

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CRD4480065) Supply either analog signals (if the Analog input option is selected) or either coaxial or opticaldigital PCM inputs (if the digital S/PDI

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CRD448007input source by pressing the Mute button. The following table shows the inputs selections: 4) Connect the DB-9 RS-232 port (J14) on the CRD4

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CRD448008 The Advanced Register Debug tab provides low level control over the CS44800 and CS8416 in-dividual register settings. Each device is disp

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CRD448009Figure 3. Advanced Register Debug Tab - CS44800