ANALOG DEVICES UG-344 Service Manual
Evaluation Board User Guide
UG-344
10359-001
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Evaluating the SSM2804 Audio Subsystem
FEATURES
Accepts either differential or single-ended inputs
Full featured evaluation board for the SSM2804
PCB footprint for optional EMI filter
Includes USB hardware interface for plug-and-play
operation
Microsoft Windows-based evaluation software with
simple graphical user interface
EQUIPMENT NEEDED
Audio source with ⅛" male stereo plug or 0.100" header
Power supply (5.0 V, 2.0 A recommended)
EVAL-SSM2804Z board
PC running Windows XP or later; USB 2.0 port required
Stereo speakers, headphones, or other load
DOCUMENTS NEEDED
SSM2804 data sheet
SOFTWARE NEEDED
SSM2804 evaluation software
GENERAL DESCRIPTION
The SSM2804 evaluation board is a complete solution for
driving two loudspeakers as well as a set of stereo headphones.
It includes the SSM2804 amplifier IC and the additional
components needed to connect the I
computer using a universal serial bus (USB) connection.
The SSM2804 features an I
tings. Using the I
input stage can be adjusted over a 30 dB range in steps of 1 dB.
Other features available when using the I
full volume control of the Class-D amplifier output stage and
the Class G headphone amplifier output stage, independent
functional block shutdown, input channel routing and mixing
through the subsystem, EMI emission control modes, speaker
protection including automatic level control (ALC), and
headphone output power limiting.
This user guide describes how to use the EVA L -SSM2804Z to
test the features of the SSM2804 stereo amplifier. It describes
the hardware and software of the SSM2804 evaluation board,
including detailed schematics and PCB layout artwork.
The SSM2804 data sheet, available at www.analog.com/SSM2804,
provides detailed information about the specifications, internal
block diagrams, and application guidance for the amplifier IC.
The SSM2804 evaluation software can be downloaded from
www.analog.com/SSM2804. Click Evaluation Boards & Kits
and choose the appropriate Windows® version (32-bit or 64-bit).
2
C control interface, the gain of the SSM2804
2
C interface with many useful set-
2
C bus to a personal
2
C interface include
Figure 1. Typical Configuration with USB Interface, USB Power, Two Inputs, and Headphone and Class-D Outputs
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
TYPICAL CONFIGURATION
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UG-344 Evaluation Board User Guide
TABLE OF CONTENTS
Features .............................................................................................. 1
Equipment Needed ........................................................................... 1
Documents Needed .......................................................................... 1
Software Needed ............................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Evaluation Board Hardware ............................................................ 3
Power Supplies .............................................................................. 3
Input Signals .................................................................................. 3
Output Signals............................................................................... 3
Shutdown and Mode Jumpers .................................................... 3
Receiver Switch ............................................................................. 3
LEDs ............................................................................................... 4
EEPROM ....................................................................................... 4
USB Power Switch ........................................................................ 4
I2C Source Jumpers ...................................................................... 4
Evaluation Board Software Quick Start Procedures .................... 5
SSM2804 Control Software Setup .............................................. 5
Initial SSM2804 Hardware Setup ............................................... 5
SSM2804 GUI Functional Blocks ................................................... 7
Input Control ................................................................................ 7
Class-D Control .............................................................................7
Speaker Protection Control .........................................................8
Headphone Control ......................................................................8
Auxiliary Functions.......................................................................9
Quick Set Buttons ..........................................................................9
Direct I2C Register Access ......................................................... 10
USB Power ................................................................................... 10
USB—I2C Interface ......................................................................... 11
General Description ................................................................... 11
USB Connector ........................................................................... 11
Power Regulator ......................................................................... 11
Cypress USB Interface ............................................................... 11
Crystal Oscillator ........................................................................ 11
Passive Component Selection ....................................................... 12
Input Coupling Capacitor Selection (C31 to C36) ............... 12
Output Ferrite Beads (B1 to B4) ............................................... 12
Output Shunting Capacitors (C43, C45, C47, and C49) ....... 12
Evaluation Board Schematics and Artwork ................................ 13
Ordering Information .................................................................... 18
Bill of Materials ........................................................................... 18
REVISION HISTORY
1/12—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
Evaluation Board User Guide UG-344
10359-002
JP8
JP9
EVALUATION BOARD HARDWARE
The SSM2804 evaluation board provides all of the support
circuitry required to operate the SSM2804 amplifier, including
a computer interface for the I
bench characterization setup used to evaluate the audio performance of the SSM2804. See the Evaluation Board Software
Quick Start Procedures section to get started.
2
C bus. Figure 1 shows the typical
POWER SUPPLIES
The SSM2804 requires two external dc power supplies: PVDD
and AVDD. PVDD voltages between 2.7 V and 5.5 V and
AVDD supply voltages between 2.5 and 3.6 V are accepted.
Note that PVDD supply currents may exceed 1 A, depending on
supply voltage and load impedance.
H3 and H4, 2-pin 0.100" male headers, are provided to connect
external supplies to the PVDD and AVDD supply rails.
Alternatively, a 5 V USB power supply can be used to power the
chip, although the USB 2.0 specification only allows a total
current draw of up to 500 mA. JP8 is used to connect USB
power to the PVDD rail, and JP9 is used to connect USB power
to the AVDD rail. These jumpers are shown in Figure 2.
Be sure to remove JP8 when using an external power supply,
because this shorts the USB voltage to the external supply.
Conversely, be sure to remove the external supply from H4
when using USB power. Be cautious of supplying any significant
amount of power when using the USB port.
For single-ended audio inputs, each channel can be used as a
stereo input. In this configuration, the signals on the INA1
and INA2 pins are called INAL and INAR, respectively. These
signals are referred to a source ground, which should be connected to the top or bottom GND pin of the header.
OUTPUT SIGNALS
Each channel of the amplifier output is available at two 2-pin
0.100" headers: H8 and H12 for the left channel, and H7 and
H11 for the right channel. The speakers are connected in
bridge-tied load (BTL) configuration, and the output pins are
labeled with their polarity; for example, OUT L+ indicates the
left channel noninverting terminal.
In the standard filterless configuration, the two headers on
each channel are connected with 0 Ω links on the pads marked
B1 to B4. In this case, the two headers on each channel are tied
together and can be used interchangeably as attachment points
for the load and an audio analyzer. The EMI filtering is not
populated on the SSM2804 evaluation board to allow proper
measurement of key parameters such as SNR and THD.
A ferrite bead-based EMI filter can be implemented using the
B1 to B4 and C43 to C50 footprints on the secondary side. If
this filtering is used, only H7 and H8 connect at the proper
location with respect to the filter components—the load must
be connected to these headers. Measurements of the unfiltered
waveform can be taken at H11 and H12.
Finally, a ground-referred Class-G headphone output is available on J2 and H13. J2 is an ordinary 0.125" headphone jack, and
H13 is a 4-pin 0.100" header connected to the same signals. The
left and right channels are connected to the center pins; the
outer pins connect to the headphone common.
Figure 2. Connecting USB Power Supply to AVDD and PVDD
INPUT SIGNALS
On the left side of the PCB are three 4-pin headers: JP5, JP6, and
JP7. These are used to connect the input audio signals to the
amplifier. If the input audio signal is differential, use the two
center pins (for example, INA1 and INA2) for the inverting and
noninverting signals. For clarity, in this configuration, the two
signals are called INA+ and INA− to emphasize their differential
nature. Connect either the top or the bottom pin to the
source/signal ground.
Rev. 0 | Page 3 of 20
SHUTDOWN AND MODE JUMPERS
A 2-pin jumper, JP10, is used to enable and disable the SSM2804
SD
amplifier. Inserting a jumper across JP10 pulls the
SPKVDD supply rail, activating the amplifier. Removing the
jumper from JP8 shuts down both channels of the SSM2804 so that
minimal current (about 20 nA) is drawn from the power supply.
pin to the
RECEIVER SWITCH
The SSM2804 includes an integrated receiver bypass switch that
can be configured to pass an audio signal directly from the
input to the output.
The switch inputs, RCV+ and RCV−, are connected to the 2-pin
header, H5. In addition, the receiver inputs can be connected to
the INA1 and INA2 input headers by shorting across H14 and
H15 with two jumpers. To protect the switch in the case of a
short circuit or other fault condition,12 Ω series resistors (R19
and R20) are included in the signal path
The switch outputs, EP+ and EP−, are connected to the 2-pin
header, H6. Alternatively, the outputs can be tied directly to the
UG-344 Evaluation Board User Guide
D1
Red
5 V power is supplied over the USB bus
10359-003
right channel Class-D outputs (H7 and H11) by shorting across
H9 and H10 with two jumpers.
LEDS
The LEDs provide feedback to the user about the status of the
Cypress USB microcontroller. The function of each LED is
shown in Tab le 1.
Table 1. LED Functions
Reference
Designator Color Function
D2 Yellow I2C mode is active
D3 Blue GPIO LED, for firmware debug purposes
D4 Yellow SPI mode is active
D5 Blue USB power switch enabled (USB_PWR_ON)
EEPROM
The USBi has an EEPROM on the I2C bus at Address 0x51, which
it uses to indicate its vendor ID and product ID to the PC, as
well as to boot its internal program. The EEPROM is an
important system element that identifies the board to the host
PC and stores the firmware for the Cypress USB interface. The
EEPROM is programmed during manufacturing via the H1
connector.
Avoid having any other EEPROMs in your system design at
this address. This EEPROM is not write-protected; therefore,
an attempt to write to Address 0x51 overwrites the USBi’s
on-board EEPROM, and the USBi will cease to function. The
USBi cannot be reprogrammed without returning it to Analog
Devices, Inc.
I2C SOURCE JUMPERS
If an external I2C source is to be used, place the JP1, JP2, and
JP3 jumpers such that they connect the device I
external I
2
I
C lines to the on-board I2C lines, as shown in the red rectangular
area of Figure 3. If an external I
2
C lines. Otherwise, they should connect the device
2
C is used, an external I2C source
can be attached to H2, following the silkscreen labels displayed
on the board.
The voltage of the external I
2
C interface should match the value
set on JP4; the two voltages are taken from two separate on-board
regulators. The on-board I
2
C interface works properly in either
configuration.
For the Cypress USB microcontroller to boot properly from the
EEPROM, it may be necessary to power down (or disconnect)
any other devices from the I
2
C bus, including the SSM2804.
In this case, remove the external 5 V supply while the USB
connection is first established, or remove the JP2 and JP3
jumpers and replace them only after the connection is activated.
Figure 3. Jumpers as Configured for On-Board I
2
C lines to the
2
C Operation
USB POWER SWITCH
The SSM2804 evaluation board is capable of taking 5 V power
from the USB port after the Cypress USB microcontroller has
finished its boot-up process. The USB_PWR_ON signal, which
can be set in the SSM2804 software, appears on one pin of the
Cypress microcontroller. This signal controls Q1 and Q2, which
create a connection between USB power and the supply rail. D5,
a blue LED, lights up when this supply is activated. Note that
the current available from the USB bus is limited; therefore, the
amplifier power stage may not drive low impedance loads
properly.
Rev. 0 | Page 4 of 20
Evaluation Board User Guide UG-344
EVALUATION BOARD SOFTWARE QUICK START PROCEDURES
SSM2804 CONTROL SOFTWARE SETUP
Do not connect the evaluation board until software is installed.
The SSM2804 software interface requires Microsoft® .NET
Framework (Version 2.0 or later). The installer automatically
downloads it if .NET Version 2.0 is not already installed.
To install the control software, use the following steps:
1. Go to www.analog.com/SSM2804.
2. Click Evaluation Boards & Kits.
3. Choose the appropriate Windows version (32-bit or 64-bit)
to download.
4. Extract the SSM2804 zipped installation file to a
convenient location and double-click setup.exe to begin
the installation process. Follow the installation instructions
when prompted.
5. The software and USB drivers are installed in C:\Program
Files\Analog Devices Inc\SSM2804.
SSM2804 USB Driver Installation
Before connecting the SSM2804 evaluation board to a PC or
notebook, the following procedure may need to be completed.
(This procedure only needs to be executed once on each computer that uses the SSM2804 software. This procedure can be
skipped if the user has previously installed any SigmaStudio
or USBi related drivers from Analog Devices.)
1. Exit the SSM2804 user interface software.
2. Remove jumpers from JP1, JP2, and JP3, located at the top
of the evaluation board, to completely isolate the Cypress
USB driver from the SSM2804.
3. Connect JP4 in the 3.3 V location as shown in the blue
circled area of Figure 3. The purpose of this is to power
the Cypress USB controller to establish communication
between the software and the board.
4. Make sure the software is closed. Connect the SSM2804
evaluation board to the PC via the USB cable.
5. The PC recognizes the new hardware. When the hardware
is recognized, a prompt asks to let Windows find the
proper drivers for the hardware. Do not let Windows
install the drivers.
6. You must direct the driver installation to the following
path by clicking the Browse tab:
C:\Program Files\Analog Devices Inc\SSM2804\
7. After the path has been properly selected, you can continue
with the driver installation process. Windows properly
establishes the link between the Cypress USB controller
and the PC.
8. After the previous steps are followed, you can run the
SSM2804 control software. The software is located at the
following path: C:\Program Files\Analog Devices
Inc\SSM2804\SSM2804.exe.
9. For quick access to this software, the installer creates a
shortcut from the SSM2804.exe file to the desktop.
10. If all steps were properly followed, at the top of the
SSM2804
onnected appears. If the installation was not successful,
C
a message of USBi – Cannot Find Device appears.
11. After a successful installation, the SSM2804 software
recognizes a connection from the PC to the SSM2804
evaluation board. There is no need to adjust the jumper
positions of JP1, JP2, and JP3, but they should be
connected as shown in Figure 3.
software window, a status message of USBi
Uninstall SSM2804 Control Software
To uninstall the software, follow these steps:
1. Locate the directory where the SSM2804 zipped installer
file was extracted.
2. Double-click setup.exe. Simply select Uninstall to remove
the software from the host PC.
INITIAL SSM2804 HARDWARE SETUP
To allow the SSM2804 software to control the SSM2804
evaluation board, you must make a few simple jumper
connections:
1. Connect the bottom and middle terminals of each jumper
(JP1, JP2, and JP3). The purpose of this is to connect the
on-board Cypress USB-I
signals connected are I
2. Connect JP4 in one of two positions, 1.8 V or 3.3 V, to
choose an I
separate on-board LDOs. The SSM2804 control interface
works well under either of these I
conditions.
2
C supply rail. These two voltages come from
2
C interface to the SSM2804. The
2
C VDD, I2C CLK, and I2C DATA.
2
C supply voltage
Rev. 0 | Page 5 of 20
UG-344 Evaluation Board User Guide
10359-004
Figure 4. SSM2804 Evaluation Software
Rev. 0 | Page 6 of 20
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