Cirrus Logic CRD4205-2 User Manual

CRD4205-2

CrystalClear® PC Audio Docking Station Companion Board

Features

lCompanion board to CRD4205-1 lEmulates Docking Station Environment

–Simulates audio portion of PC docking station. –Digital Interface to CRD4205-1

lHigh quality, low cost analog to digital (ADCs)

and digital to analog (DACs) converters

– CS5334 18-bit serial ADCs – CS4334 24-bit serial DACs

lPCI Slot card (power only) lTwo stereo inputs lOne microphone inpu t lFour channel audio output

Description

The CRD4205-2 reference design is a comp anion card to the CRD4205-1. The CRD4205-2 emulates the audio sub-system in a PC digital docking station, and the CRD4205-1 simulates the audio sub-system in a PC notebook computer.

This reference design features stereo analog inputs for Line, CD, and a mono input for Microphone. The card also has four channel analog audio outputs. The docking port is completely digital. The analog inputs in the CRD4205-2 are processed by high quality 18-bit serial ADCs. The analog outputs are processed by high quality serial 24-bit DACs.

The CRD4205-2 is available by ordering the CMK42053 manufacturing kit. This kit includes a full set of sc hematics (OrCAD ASCII), PCB Gerber files, bill of materials and WDM audio drivers that support Windows 98se, Millennium Windows 2000.

ORDERING INFORMATION

CMK4205-3 Manufacturing Kit for the CRD4205-2

7.2 format), PCB job files (PADS

and

CD IN

MIC IN

LINE IN LINE OUT1 LINE OUT2

JP1

CRD4205-2

CS5331A

CS4334

Preliminary Product Information

P.O. Box 17847, Austin, Texas 78760 (512) 445 7222 FAX: (512) 445 7581 http://www.cirrus.com

DOCKING

PORT

This document contains information for a new product. Cirrus Logic reserves the right to modify this product without notice.

CS4205

CRD4205-1

DS489RD2A1

DEC ‘00

TABLE OF CONTENTS

1. GENERAL INFORMATION ..........................................................................3

2. SCHEMATIC DESCRIPTION ....................................................................... 3

2.1 Block Diagram ....................... ...... ....... ...... ............................................ 3

2.2 Analog Inputs ......................................................................................3

2.3 Analog Output ...................................................................................... 3

2.4 PCI Bus ...............................................................................................4

2.5 Component Selection ........................................................................... 4

2.6 EMC Components ................................................................................ 4

3. GROUNDING AND LAYOUT ....................................................................... 4

4. REFERENCES ............................................................................................. 5

5. ADDENDUM ..................... .......................... ......................... ......................... 5

6. BILL OF MATERIALS ............................................................................15

Printed Circuit Board Assembly.................................................................15

Mechanical Assembly................................................................................16

LIST OF FIGURES

Figure 1. Block Diagram........................................................................................... 6

Figure 2. Analog In................................................................................................... 7

Figure 3. Analog Out ................................................................................................ 8

Figure 4. PCI Bus......................................................... ...... ....... ...... ....... ...... ............ 9

Figure 5. Assembly Drawing .................................................................................. 10

Figure 6. Silkscreen................................................................................................ 11

Figure 7. Top Layer................................................................................................ 12

Figure 8. Bottom Layer................. ...... ....... ...... ....... ...... ...... ....... ............................. 13

Figure 9. Drill Drawing............................................................................................ 14

CRD4205-2

LIST OF TABLES

Table 1. Microphone Input Jumper JP1 ................................................................... 3

Contacting Cirrus Logic Support

For a complete listing of Direct Sales, Distributor, and Sales Representative contacts, visit the Cirrus Logic web site at:

http://www.cirrus. com/corporat e/contact s/

Microsoft, Windows 95, Windows 98 and Windows Millenium and WHQL is registered trademark of Microsoft. CrystalClear is a trademark of Cirrus Logic, Inc. Intel is a registered trademark of Intel Corporation. OrCAD is a registered trademark of OrCAD, Inc. PADS is a registered trademark of, PADS Software, Inc.

Preliminary product information describes products which are in production, but for which full characterization data is not yet available. Advance product information describes products which are in develo pment and subj ect to devel opment changes. Cirr us Logic, Inc. has made best ef forts to en sure t hat the inf ormati on contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided “AS IS” without warranty of any kind

(express or im plied). No responsib ility is assu med by Cir rus Logic, Inc. for the use of this information, nor for infringements of patents or other rights of third parties. This document is the property of Cirrus Logic, Inc. and implies no license under patents, copyrights, trademarks, or trade secrets. No part of this publication may be copied, reproduced, stored in a retrieva l system, or transm i tted, i n an y form or by any m eans (e l ectron i c, mechani cal , pho togra phi c, or otherwise) without th e prior written consent of Cirrus Logic, Inc. Items from any Cirrus Logic websi te or disk may be printed for use by the user. H owever , no par t of t he pri ntout o r electronic files may be copied, reprodu ced, stored in a retrie val system, or transmitted, i n any form or by any means (electro nic, mechanical, photographic, o r otherwise) without the prior written consent of Cirrus Logic, Inc.Furthermore, no part of this publication may be used as a basis for manufacture or sale of any it ems without the prior written consent of Cirrus Logic, Inc. The names of products of Cirrus Logic, Inc. or other vendors and suppliers appearing in this document may be trademarks or service marks of their respective owners which may be registered in some jurisdictions. A list of Cirrus Logic, Inc. trademarks and service marks can be found at http://www.cirrus.com.

2 DS489RD2A1

CRD4205-2

1.GENERAL INFORMATION

The CRD4205-2 is designed to emulate a high quality PC audio docking station. This is not a stand-alone card but used in conjunction with the CRD4205-1. The CRD4205-1 contains a CS4205 audio codec and simulates the audio sub-system in a PC notebook computer.

The CRD4205-2 has all the circuitry typically found in a high quality PC digital docking audio sub-system. In addition, this reference design includes four channel analog audio outputs driven by 24-bit serial DACs. Microphone, stereo Line, and stereo CD inputs feature high quality serial 18-bit ADCs.

2.SCHEMATIC DESCRIPTION

This section describes the CRD4205-2 schematics shown in figures 1 through 4. These schematics are also available in the CMK4205-3 manufacturing kit as ORCAD 7.2 files.

2.1 Block Diagram

The analog audio input signals are converted to digital data by three CS5331A 18-bit ADCs. The ADCs share a common clock, but have independent data outputs. The clock and serial data signals are routed to the docking port header.

The MIC IN circuit complies with PC-99 requirements for microphone phantom power and recommendations for frequency response roll-off. The 3dB roll-off frequencies are 60Hz and 15kHz. Phantom power for the microphones is derived from the +5V analog supply and filtered by R11, C13, and R12.

Jumper JP1 controls how the microphone signal is routed to the ADC, U3.

JP1 Position Description

Out Microphone signal routed to AINL of

the CS5331A. The AINR is floating. 1-2 Not Used! 2-3 Microphone signal routed to both

AINL and AINR of the CS5331A.

Table 1. Microphone Input Jumper JP1

The block diagram in Figure1, shows the interconnection between schematic pages. The schematic is divided into three blocks: Analog In, Analog Out, and PCI Bus.

2.2 Analog Inputs

The Analog Input page in Figure2 illustrates the Mic, stereo Line and stereo CD inputs and their associated ADCs. The LINE inputs connect to a divider circuit that reduces the voltage by 6dB to allow for line level sources up to 2Vrms. The 100pF capacitors are provided on Line In and Mic In for EMI suppression. These may be removed if EMC testing determines they are not required.

Since the analog inputs of the CS5331 ADCs are DC biased, all of the analog inputs must be AC coupled. The microphone input is coupled with a

0.1µF capacitor. The Line and CD inputs are AC

coupled with 2.2µF capacitors to minimize the low frequency roll-off.

2.3 Analog Output

The CS4205 sends audio to the docking port through I2S serial digital outputs, as shown in figure3. These signals are converted to analog audio through two CS4334 serial DACs. Both CS4334s share common clocks but have independent data inputs. All clocks originate from the CS4205 on the CRD4205-1 card.

The output of the DACs are connected to a Motorola MC34072 dual op-amp which is capable of driving high impedance (10kΩ or higher) line level signals. This circuit has a gain of 3dB.

It is possible to drive headphones with impedances as low as 32Ω by replacing the MC34072 with a TDA1308 and increasing the values of C23, C24, C29, and C30 to 220µF. These op-amps are pin compatable.

DS489RD2A1 3

CRD4205-2

2.4 PCI Bus

The PCI bus is only used to supply power to the board, so that an external supply is not required. The PCI bus connections are shown in Figure 4. The digital power is supplied from the PCI bus. A Motorola MC78M05C regulates the +12 V supply from the PCI bus down to a clean +5 V analog supply. For the best audio performance, the analog voltage regulator is located over the analog ground plane near the partition between the analog and digital planes. The regulator ground pin is connected to the analog ground.

Figure 4 also shows the docking port header. This connector couples the serial data from the CRD4205-1 and is buffered by a 74HC244 octal buffer.

2.5 Component Selection

Great attention was given to the particular components used on the CRD4205-2 board with cost, performance, and package selection as the most important factors. Listed are some of the guidelines used in the selection of components:

• No components smaller than 0805 package.

• Only single package components; no resistor packs.

• All ICs are in surface mount packages.

2.6 EMC Components

A number of capacitors and inductors are included to help the board meet EMI compliance tests, such as FCC Part 15. The EMC part values are only

meant as starting points. Modify these values to meet individual EMC requirements.

3. GROUNDING AND LAYOUT

One of the most critical aspects of PC audio design is good PC board layout. The PC is a hostile environment for audio, and good layout is essential for achieving high audio quality.

The CRD4205-2 is partitioned into a digital and analog sections to help isolate noisy digital circuitry from quiet analog audio circuitry. The most important rule for successful PC audio layout is to keep all digital signal traces and components over the digital ground plane, and all analog signal traces and components over an analog ground plane. These planes are separated by a minimum of 60 to 100 mils (0.060 to 0.100 inches).

When digital and analog signals cross planes, they introduce noise into the audio section reducing performance. The CS4334 DACs and CS5331A ADCs are placed over the partition of the analog and digital ground planes. The ADCs and DACs both have their analog and digital signals partitioned to opposite sides of the ICs to help simplify PCB layout. Digital and analog ground are tied together by a wide trace (over 50 mils or

0.050 inches) at a single point underneath the converters in order to provide a common ground reference.

For more information on layout specifically for the CS4334 and the CS5331A, see their respective datasheets.

4 DS489RD2A1

CRD4205-2

4. REFERENCES

1) Intel, Audio Codec ‘97 Component Specification, Revision 2.1, May 22, 1998. http://developer.intel.com/ial/scalableplatforms/audio/

2) Communication and Network Riser Specification revision 1.0, Feb 7, 2000 http://developer.intel.com/technology/cnr/

3) Steve Harris, Clif Sanchez, Personal Computer Audio Quality Measurements, Ver 1.0

http://www.crystal.com/pubs/meas100.pdf

4) Cirrus Logic, CS4205 Data Sheet

5) Cirrus Logic, CS4334/5/6/7/8/9 Data Sheet

http://www.crystal.com/pubs/4334.pdf

6) Cirrus Logic, CS5330A/31A Data Sheet

http://www.crystal.com/pubs/5330a.pdf

5. ADDENDUM

• Schematic drawings

• Layout drawings

DS489RD2A1 5

6 DS489RD2A1

Main Board

Analog_In

>Line In

>CD In

>Mic In

Analog_In

DSSDI1

DSSDI3

DSSDI2

DSMCK

DSLRCK

DSSCK

PCI_Bus

> Clocks > SDO1 > SDO2 < SDI1 < SDI2 < SDI3

PCI_Bus

DSSDI2

DSSDI1

DSSDI3

DSMCK

DSSCK

DSLRCK

Analog_Out

DSMCK DSLRCK DSSCK

Analog_Out

SDATA2

SDATA1

SDATA2

Line1 Out >

Line2 Out >

Figure 1. Block Diagram

CRD4205-2

+ 12 hidden pages