Copyright © Cirrus Logic, Inc. 2006
(All Rights Reserved)
http://www.cirrus.com
Evaluation Board for CS3308
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® Compatible Software Interface
– Easy and Intuitive Graphical Interface to
Channel and Master Volume Controls
– Supports USB and RS-232 PC
Connectivity
Description
The CDB3308 evaluation board is an excellent means
for evaluating the CS330 8 analog vo lume control. Eval-
uation requires an analog signal source and analyzer,
power supplies, and a Windows PC compatible
computer.
Standard RCA phono jacks are pr ovided to easily inte r-
face external analog signals with the evaluation board.
Each of the CS3308’s inputs and outputs may be inde-
pendently AC or DC-coupled to their respective I/O
connectors.
The Windows software provides a GUI to make config-
uration of the CDB3308 easy. The software
communicates through the PC’s USB or Serial port to
configure the contro l port registers so that all features of
the CS3308 can be evaluated.
As an alternative to the se rial control pr ovided via a PC,
the evaluation board may be configured to accept exter-
nal control signals for operation in a user application
during system development.
To facilitate multi-CS3308 system design efforts, head-
ers are provided for connecting serial control signals
between multiple CDB3308 evaluation boards.
ORDERING INFORMATION
CDB3308 Evaluation Board
CS3308
8-Channel
Digitally Controlled
Analog Volume Control
8-Channel
Passive
Inputs
AC/DC
Coupling AC/DC
Coupling
8-Channel
Passive
Outputs
USB/RS232
PC Interface PC or External
Serial Control Input External
Serial Control Output
CDB3308
MAY '06
DS702DB2
2DS702DB2
CDB3308
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
LIST OF TABLES
Table 1. System Connections ..................................................................................................................... 8
Table 2. On-Board Switches ....................................................................................................................... 8
Table 3. System Headers ............................................................................................................................ 8
DS702DB2 3
CDB3308
1. SYSTEM OVERVIEW
The CDB4265 evaluation board is an excellent means for evaluating the CS33 08 digita lly contro lled analog volum e
control. Anal og audio s ignal inte rfaces ar e provid ed, 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 refe 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 perfor-
mance. Figure 7 on page 9 provides an overview of the connections to the CS3308. Figure 11 on page 13
shows the component pl acement. Figure 12 on pa ge 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 register-level configuration inte rface is pro-
vided 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 SPITM/I²C® and MUTE
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 cab le’s ground connection is pr ovided to maintain sign al
integrity. Tw o unpo pulated pull-up resistors ar e also available should the CDB3308 be required to provide
the pull-up function for the I²C bus.
The 10-pin, 2 column header, J89, provides bidirectio nal access to the CS3308’s I²C SDA a nd SCL signals,
as well as unidirectional outpu t access to the CS3308’s AD0, ENOut, and MUTE signals. T he SDA and SCL
signals are connected directly to their corresponding pins on the CS3308, as well as those on J17 described
above. The AD0, ENOut, and MUTE signals are re-driven versions of these signals as present directly on
their respective I/O pins on the CS3308. This header may be used to connect the serial control signals be-
tween 2 or more CDB3308’s (out of J89 on one and in to J17 on another) for multiple CS3308 I²C serial
control evaluation.
4DS702DB2
CDB3308
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 signals. All of the signals re-driven versions of those
present directly on their respective I/O pins on the CS330 8. This heade r ma y b e used to co nne ct the serial
control signals between 2 or more CDB3308’s (out of J88 on one and in to J17 on another) for multiple
CS3308 SPI serial control evaluation.
1.5 Analog Inputs
RCA connectors supply the CS3308 analog inpu ts through single-ended passive circu its with no input filter-
ing. 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 place d adjacent to each input connector on the board. To
DC couple an input conne ctor, place a shu nt across the resp ective hea der. To AC couple a n input connec-
tor, 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 lab eled “DC Co uple Outp ut” and placed 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 re spective head er. By default, the output connectors are AC coup led
to the CS3308’s outputs.
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 availab le for the CDB3308 to allow easy manipulation of th e 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 (J3 7), or alternatively con nect 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).
DS702DB2 5
CDB3308
2. PC SOFTWARE CONTROL
The CDB3308 is designed for use with the Microsoft Windows based FlexGUI graphical user interface. This inter-
face 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, ne gative 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 “Po we r Dow n CS3 308” che ck bo x to allow au dio to pass th ro ug h th e device .
2.1 CS3308 Controls Tab
The CS3308 Controls tab provides a hig h-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.
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.
Figure 1. CS3308 Controls Tab
6DS702DB2
CDB3308
2.2 Register Maps Tab
The Register Maps tab provides an easy register-level interface to the on-board devices. Register values
can be modified on a bit-wise or byte-wise basis. To modify a single bit, first select the register by clicking
its position in the register matrix, then click the appropriate push-button for the desired bit. To modify an
entire register, simply enter the register’s new value directly into the register matrix.
Within the Register Map s tab, the CS3308 tab is used to access the CS3308’s internal registers, and the
GPIO tab is used to access the on-board microcontroller outputs used to control the CS3308’s MUTE input
and default I²C address.
The Comm Mode Select box may be used to chang e the CS3308’s serial communication p rotocol between
I²C and SPI. The CS3308 will be automatically reset when the communication protoc ol is changed.
The software is only capable of addressing the CS3308 at its default address. If the CS3308’s individual
address is changed, the software will loose communication with the device until it is reset, thereby returning
to its default address. See the CS3308 datasheet for more information about the device’s individual ad-
dress.
Figure 2. Register Maps Tab
DS702DB2 7
CDB3308
3. PERFORMANCE PLOTS
(TA= +25 ºC, VA+ = +5 V, VA- = -5 V, VD = +3.3 V, RL=100kΩ, CL=20pF, V
IN =2V
RMS, FIN =1kHz,
Gain = 0 dB, Measurement Bandwidth = 20 Hz to 20 kHz, unless otherwise noted.)
-1
+1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
+0
+0.1
+0.2
+0.3
+0.4
+0.5
+0.6
+0.7
+0.8
+0.9
d
B
r
A
20 200k50 100 200 500 1k 2k 5k 10k 20k 50k 100k
Hz
0.0001
1
0.0002
0.0005
0.001
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
%
100m 3200m 300m 400m 500m 600m 700m 800m900m 1 2
Vrms
Figure 3. Frequency Response Figure 4. THD+N vs. Amplitude
0.0001
1
0.0002
0.0005
0.001
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
%
20 20k50 100 200 500 1k 2k 5k 10k
Hz
-180
+0
-170
-160
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Figure 5. THD+N vs. Frequency Figure 6. Crosstalk
8DS702DB2
CDB3308
4. SYSTEM CONNECTIONS & JUMPERS
Connector
Name Reference
Designator Signal
Direction Connector Function
GND J5 Input Ground reference.
VA+ J8 Input Positive analog power. +5 V.
VA- J7 Input Negative analog power. -5 V.
In 1
In 2
In 3
In 4
In 5
In 6
In 7
In 8
J29
J27
J11
J15
J55
J57
J71
J73
Input Analog input to CS3308.
Out 1
Out 2
Out 3
Out 4
Out 5
Out 6
Out 7
Out 8
J19
J21
J46
J48
J62
J64
J79
J81
Output Analog output from CS3308.
USB I/O J37 Input/Output USB connection to PC for software control.
RS-232 I/O J42 Input/Output Serial RS-232 connection to PC for software control.
I²C/SPI Input J17 Input/Output Connection for internal/external I²C/SPI control signals.
I²C Output J89 Output Output connection for on-board I²C control signals.
SPI Output J88 Output Output connection for on-board SPI control signals.
C2 J36 Input/Output Connection for programming the on-board microcontroller (U46).
Table 1. System Connections
Switch Name Reference Designator Switch Function
uC Reset J5 Resets the on-board microcontroller (U46).
Table 2. On-Board Switches
Connector Name Reference
Designator Header Function
DC Couple Input 1
DC Couple Input 2
DC Couple Input 3
DC Couple Input 4
DC Couple Input 5
DC Couple Input 6
DC Couple Input 7
DC Couple Input 8
J2
J3
J16
J18
J58
J59
J74
J75
When a shunt is present across its pins, each header DC couples its respec-
tive input connector to the associated input of the CS3308.
When no shunt is present across the header’s pins, its respective input con-
nector will be AC coupled to the associated input of the CS3308.
DC Couple Output 1
DC Couple Output 2
DC Couple Output 3
DC Couple Output 4
DC Couple Output 5
DC Couple Output 6
DC Couple Output 7
DC Couple Output 8
J32
J33
J51
J52
J67
J68
J84
J85
When a shunt is present across its pins, each header DC couples its respec-
tive output connector to the associ ated output of the CS3308.
When no shunt is present across the header’s pins, its respective output
connector will be AC coupled to the associated outpu t of the CS3308.
Table 3. System Headers
16 DS702DB2
CDB3308
8. REVISION HISTORY
Release Changes
DB1 Initial Release
DB2 Updated performance plots shown in Figures 3-6 on page 7.
Contacting Cirrus Logic Support
For all product questions and inq uiries, contact a Cirrus Logic Sales Repr esentative.
To find the one nearest to you, go to www.cirrus.com.
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Cirrus Logic, Cirrus, and the Cirrus Logic logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks
or service marks of their respective owners.
SPI is a trademark of Motorola, Inc.
I²C is a registered trademark of Philips Semiconductor.
Windows is a registered trademark of Microsoft Corporation.
