Cirrus Logic CDB3308 User Manual
Evaluation Board for CS3308
CDB3308
Features
Single-ended Analog Inputs
Single-ended Analog Outputs
Supports AC and DC-Coupled Analog I/O
Flexible Serial Control I/O Headers
– Serial Control Input Header to
Accommodate On-board and External
Serial Controllers
– Serial Control Output Headers for
“Chaining” Serial Control Across Multiple
CDB3308 Evaluation Boards
– 3.3 V Logic Interface Level
Demonstrates Recommended Layout and
Grounding Arrangements
Minimal Power Supply Requirements
– ±5 V and Ground
Windows
– Easy and Intuitive Graphical Interface to
– Supports USB and RS-232 PC
®
Compatible Software Interface
Channel and Master Volume Controls
Connectivity
Description
The CDB3308 evaluation board is an excellent means
for evaluating the CS3308 analog volume control. Evaluation requires an analog signal source and analyzer,
power supplies, and a Windows PC compatible
computer.
Standard RCA phono jacks are provided to easily interface external analog signals with the evaluation board.
Each of the CS3308’s inputs and outputs may be independently AC or DC-coupled to their respective I/O
connectors.
The Windows software provides a GUI to make configuration of the CDB3308 easy. The software
communicates through the PC’s USB or Serial port to
configure the control port registers so that all features of
the CS3308 can be evaluated.
As an alternative to the serial control provided via a PC,
the evaluation board may be configured to accept external control signals for operation in a user application
during system development.
To facilitate multi-CS3308 system design efforts, headers are provided for connecting serial control signals
between multiple CDB3308 evaluation boards.
ORDERING INFORMATION
CDB3308 Evaluation Board
8-Channel
Passive
Inputs
USB/RS232
PC Interface
http://www.cirrus.com
AC/DC
Coupling
CS3308
8-Channel
Digitally Controlled
Analog Volume Control
PC or External
Serial Control Input
Copyright © Cirrus Logic, Inc. 2006
(All Rights Reserved)
AC/DC
Coupling
External
Serial Control Output
8-Channel
Passive
Outputs
MAY '06
DS702DB2
TABLE OF CONTENTS
1. SYSTEM OVERVIEW ............................................................................................................................. 3
1.1 Power ............................................................................................................................................... 3
1.2 Grounding and Power Supply Decoupling ...................... ... .... ... ... ... ... .... ........................................... 3
1.3 CS3308 Analog Volume Control ..................... ... ... .... ... ... ... .... ... ... ... ... .... ... ........................................ 3
1.4 External Control Headers ................................................................................................................. 3
1.5 Analog Inputs .................................................................................................................................... 4
1.6 Analog Outputs ................................................................................................................................. 4
1.7 PC Interfaces .................................................................................................................................... 4
2. PC SOFTWARE CONTROL ................................................................................................................... 5
2.1 CS3308 Controls Tab ....................................................................................................................... 5
2.2 Register Maps Tab ........................................................................................................................... 6
3. PERFORMANCE PLOTS ....................................................................................................................... 7
4. SYSTEM CONNECTIONS & JUMPERS ................................................................................................8
5. CDB BLOCK DIAGRAM ........................................................................................................................ 9
6. CDB SCHEMATICS .............................................................................................................................. 10
7. CDB LAYOUT ....................................................................................................................................... 13
8. REVISION HISTORY ............................................................................................................................ 16
LIST OF FIGURES
Figure 1.CS3308 Controls Tab .................................................................... .... ... ... ..................................... 5
Figure 2.Register Maps Tab ............................ ... .... ... ... ... .... ... ... ... .... ... ... ... ... .... ........................................... 6
Figure 3.Frequency Response .................................................................................................................... 7
Figure 4.THD+N vs. Amplitude .................................... ... .... ... ... ... .... ... ... ... .................................................. 7
Figure 5.THD+N vs. Frequency ...................................... .... ... ..................................................................... 7
Figure 6.Crosstalk .............................................. .... ... ... ....................................... ... ... .... .............................. 7
Figure 7.Block Diagram ............................. ... ... ... .... ... ... ... .......................................... .... ... ........................... 9
Figure 8.CS3308 ... ... .... ... ... ... .... ... ................................................................................. ............................ 10
Figure 9.Analog Inputs and Outputs ...................................................................... ... .... ... ... ...................... 11
Figure 10.Serial Control / Power ............................................................................................................... 12
Figure 11.Silkscreen Top ....................... ... ... ... ... .... ... ... ... .... .......................................... ... ... ...................... 13
Figure 12.Top Side Copper Layer ... ... .... ... ... ............................................................................................. 14
Figure 13.Bottom Side Copper Layer ........................................................................................................ 15
CDB3308
LIST OF TABLES
Table 1. System Connections ..................................................................................................................... 8
Table 2. On-Board Switches ....................................................................................................................... 8
Table 3. System Headers ............................................................................................................................ 8
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CDB3308
1. SYSTEM OVERVIEW
The CDB4265 evaluation board is an excellent means for evaluating the CS3308 digitally controlled analog volume
control. Analog audio signal interfac es are pro vided, an on-board microcontroller and USB/RS-232 PC interface is
used for easily configuring the CS3308’s internal registers, and a USB cable is included for use with the FlexGUI
Windows configuration software.
The CDB3308 schematic set is shown in Figure 8 through Figure 10.
1.1 Power
Power (±5 V) must be supplied to the evaluation board through the red VA+ and green VA- binding posts.
An on-board regulator provides a 3.3 V supply to the digital circuitry. All voltage inputs must be re fe re n ced
to the single black binding post ground connector (see the System Connections table on page 8).
WARNING: Please refer to the CS3308 data sheet for allowable voltage levels.
1.2 Grounding and Power Supply Decoupling
The CS3308 requires careful attention to power supply and grounding arrangements to optimize performance. Figure 7 on page 9 provides an overview of the connections to the CS3308. Figure 11 on page 13
shows the component placement. Figure 12 on page 14 shows the top layout. Figure 13 on page 15 shows
the bottom layout. The decoupling capacitors are located as close to the CS3308 as possible. Extensive
use of ground plane fill in the evaluation board yields large reductions in radiated noise.
1.3 CS3308 Analog Volume Control
A complete description of the CS3308 is included in the CS3308 product data sheet.
The required configuration settings of the CS3308 are achieved via its control port registers, accessible
through the CS3308 tab of the Cirrus Logic FlexGUI software. A reg ister-level configuration interface is p rovided on the Register Maps tab. See the “PC Software Control” section on page 5 for more information.
1.4 External Control Headers
The evaluation board has been designed to allow interfacing with external systems via the headers J17,
J88, and J89.
The 15-pin, 3 column header, J17, provides bidirectional access to the CS3308’s SPI
digital control signals. The pins located in the column labeled “PC” connect to the on-board PC interface
circuitry, and those in the co lumn labeled “In” co nnect directly to t he CS3308’s digital co ntrol I/O pins. By
default, shunts are populated across these rows, connecting the PC interface to the CS3308’s digital control
I/O. To use an external digital control source, simply remove the shunts and connect a ribbon cable to the
“In” position. A single “GND” column for the ribbon cable’s ground connection is provided to mainta in signal
integrity. Two unpopulated pu ll-up resisto rs are a lso available should the CDB3308 be required to provide
the pull-up function for the I²C bus.
The 10-pin, 2 column header, J89, provides bidirectional access to the CS3308’s I²C SDA and SCL signals,
as well as unidirectional output access to the CS3308’s AD0, ENOut, and MUTE
signals are connected directly to their corresponding pi ns on the CS3308, as well as those on J17 described
above. The AD0, ENOut, and MUTE
their respective I/O pins on the CS3308. This header may be used to connect the serial control signals between 2 or more CDB3308’s (out of J89 on one and in to J17 on another) for multiple CS3308 I²C serial
control evaluation.
signals are re-driven versions of these signals as present directly on
TM
/I²C® and MUTE
signals. The SDA and SCL
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The 10-pin, 2 column header, J88, provides unidirectional output access to the CS3308’s SPI MOSI and
CCLK signals, as well as its AD0, ENOut, and MUTE
present directly on their respective I/O pins on the CS3308. This header may be used to co nne ct the serial
control signals between 2 or m ore CDB3308’s (out of J88 on one an d in to J17 on another) for multiple
CS3308 SPI serial control evaluation.
1.5 Analog Inputs
RCA connectors supply the CS3308 analog inputs through single-ended passive circuits wi th no input filtering. Refer to the CS3308 data sheet for the maximum input signal level.
Each analog input may be AC or DC coupled to its respective RCA connector. This selection is made via
the 2-pin headers labeled “DC Couple Input” and placed adjacent to each input connector on the board. To
DC couple an input connector, place a shunt across the respective heade r. To AC couple an in put connector, remove the shunt from the respective header. By default, the input connectors are AC coupled to the
CS3308’s inputs.
1.6 Analog Outputs
The CS3308 analog outputs are routed through single-ended passive circuits with no output filtering and
connected to RCA jacks for easy evaluation.
Each analog output may be AC or DC coupled to its respective RCA connector. This selection is made via
the 2-pin headers labeled “DC Couple Output” and pla ced adjacent to each output connector on the board.
To DC couple an output connector, place a shunt across the respective header. To AC couple an output
connector, remove the shunt from the resp ective head er. By default, the output connectors are AC coupled
to the CS3308’s outputs.
CDB3308
signals. All of the signals re-driven versions of those
1.7 PC Interfaces
USB and RS-232 connections are provided to facilitate software control of the CS3308’s internal registers.
A graphical user interface is available for the CDB3308 to allow easy manip ulation of the CS3308’s internal
registers. See the CS3308 datasheet for complete internal register descriptions.
To enable the CDB3308, simply connect the supplied USB cable from an available USB port on a PC to the
USB connector (J37), or alternatively connec t a 9-pin serial cable from an available COM port on a PC to
the RS-232 connector (J42) and launch the Cirrus Logic FlexGUI software.
Refer to “PC Software Control” on page 5 for a description of the Graphical User Interface (GUI).
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CDB3308
2. PC SOFTWARE CONTROL
The CDB3308 is designed for use with the Microsoft Windows based FlexGUI graphical user interface. This interface provides comprehensive control over the CS3308’s internal registers via a PC’s USB or RS-232 port.
The FlexGUI software may be downloaded and installed from www.cirrus.com/msasoftware.
Step-by-step instructions for using the FlexGUI are provided as follows:
1. Download and install the FlexGUI software from www.cirrus.com/msasoftware.
2. Connect the CDB3308 to a host PC using the supplied USB cable or a 9-pin serial cable.
3. Apply positive power, negative power, and ground to the VA+, VA-, and GND binding posts respectively.
4. Launch the FlexGUI software. The GUI will load and be displayed.
5. Un-check the “Power Down CS3308” check box to allow audio to pass th ro ug h th e de vice.
2.1 CS3308 Controls Tab
The CS3308 Controls tab provides a high-level intuitive interface to many of the configuration options of the
CS3308. Control over the state of the CS3308’s MUTE
and RESET input pins is also provided.
Figure 1. CS3308 Controls Tab
The Master X Mask check boxes are used to map each channel to the master controls. These check-boxes
reflect the state of their associated Master X Mask bits; when checked, the channel is un-masked.
The sliders facilitate control over the Ch X Volume registers, providing gain and attenuation in ½ dB steps.
The +¼ dB Gain check boxes are used to add an additional ¼ dB of gain to the volume level displayed for
each channel.
See the CS3308 datasheet for complete internal register descriptions.
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