ANALOG DEVICES UG-248 Service Manual
Evaluation Board User Guide
UG-248
09686-001
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 SSM2380 Audio Amplifier
FEATURES
Accepts either differential or single-ended inputs
Full featured evaluation board for the SSM2380
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-SSM2380Z evaluation board
PC running Windows XP or later; USB 2.0 port required
Stereo speakers or other load
DOCUMENTS NEEDED
SSM2380 data sheet
SOFTWARE NEEDED
SSM2380 evaluation software
TYPICAL I2C INTERFACE CONFIGURAT ION
GENERAL DESCRIPTION
The SSM2380 evaluation board is a complete solution for
driving two loudspeakers. It includes the SSM2380 amplifier
IC and the additional components needed to connect the I
bus to a personal computer using a universal serial bus (USB)
connection. Figure 1 shows the evaluation board in a simple
configuration with USB and power and audio input connections.
The SSM2380 features an I
settings. Using the I
SSM2380 can be selected from any of 47 values between
1 dB and 24 dB. Other features available when using the I
interface include independent left/right channel shutdown,
EMI emission control modes, automatic level control (ALC),
and stereo-to-mono input mixing.
This user guide describes how to use the EVA L -SSM2380Z to
test the features of the SSM2380 stereo amplifier. It describes
the hardware and software of the SSM2380 evaluation board,
including detailed schematics and PCB layout artwork.
The SSM2380 data sheet, available at www.analog.com/SSM2380,
provides detailed information about the specifications, internal
block diagrams, and application guidance for the amplifier IC.
The SSM2380 evaluation software can be downloaded from
www.analog.com/SSM2380. Click Evaluation Boards & Kits
and choose the appropriate Windows version (32-bit or 64-bit).
2
C interface with many useful
2
C control interface, the gain of the
2
C
2
C
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
Figure 1. EVAL-SSM2380Z Evaluation Board
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UG-248 Evaluation Board User Guide
TABLE OF CONTENTS
Features .............................................................................................. 1
Equipment Needed ........................................................................... 1
Documents Needed .......................................................................... 1
Software Needed ............................................................................... 1
General Description ......................................................................... 1
Typ ical I2C Interface Configuration ............................................... 1
Revision History ............................................................................... 2
Evaluation Board Hardware ............................................................ 3
Power Supplies .............................................................................. 3
Input Signals .................................................................................. 3
Output Signals............................................................................... 3
Shutdown and Mode Jumpers .................................................... 3
LEDs ............................................................................................... 4
EEPROM ....................................................................................... 4
USB Power Switch ........................................................................ 4
I2C Source Jumpers ...................................................................... 4
Operating Modes .............................................................................. 5
I2C Control Mode ......................................................................... 5
ALC Mode ..................................................................................... 5
Gain Select Mode .......................................................................... 5
Evaluation Board Software Quick Start Procedures .................... 6
SSM2380 Control Software Setup .............................................. 6
Initial SSM2380 Hardware Setup ................................................6
SSM2380 GUI Functional Blocks ....................................................8
Input Control .................................................................................8
Output Control ..............................................................................8
Auxiliary Functions.......................................................................9
Quick Set Buttons ....................................................................... 10
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 (C22 to C25) ............... 12
Output Ferrite Beads (B1 to B4) ............................................... 13
Output Shunting Capacitors (C29 to C32) ............................. 13
Output Inductors (L1 to L4) ..................................................... 13
Evaluation Board Schematics and Artwork ................................ 14
Ordering Information .................................................................... 18
Bill of Materials ........................................................................... 18
REVISION HISTORY
9/11—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
Evaluation Board User Guide UG-248
1/8” STEREO
INPUT
OR
DIFERENTIAL
AUDIO INPUT
TO PC
EXTERNAL I
2
C
TO LOAD
2.5V TO 5.5V
TO ANALYZER
09686-002
09686-003
EVALUATION BOARD HARDWARE
The SSM2380 evaluation board provides all of the support
circuitry required to operate the SSM2380 amplifier, including
a computer interface for the I
2
C bus. Figure 2 shows the typical
bench characterization setup used to evaluate the audio performance of the SSM2380. See the Evaluation Board Software
Quick Start Procedures section to get started.
Figure 2. Diagram View of Evaluation Board Connections
POWER SUPPLIES
The SSM2380 requires an external dc power supply. A 2-pin
0.100" male header, H3, is provided on the evaluation board.
Supply voltages between 2.5 V and 5.5 V are accepted, and
supply currents may exceed 1 A under some conditions.
Alternatively, 5 V USB power supply can be used to power the
chip, although the USB 2.0 specification only allows current
draw up to 500 mA. Be cautious when using the USB port
to supply any significant amount of power. The jumper
configuration used for USB power is shown in Figure 3.
Be sure to remove JP7 when using an external power supply,
as this will short the I
Conversely, be sure to remove the external supply from
H3 when using USB power.
Figure 3. Connecting USB Power Supply to SSM2380
2
C voltage to the external supply.
INPUT SIGNALS
On the left side of the PCB are two 4-pin headers, JP5 and JP6.
These are used to connect the input audio signal to the amplifier. If
the input audio signal is differential, use the two center pins of
JP5 (INL+ and INL−) for left channel audio and the two center
pins of JP6 (INR+ and INR−) for the right channel audio. In
this case, connect either the top or the bottom pin to the source/
signal ground.
For single-ended audio inputs, only two pins of JP5 and two
pins of JP6 are used: ground and the input signal. If a noninverting input is desired, connect the input signals to INL+
and INR+, and place jumpers between Pin 3 and Pin 4 of JP5
and JP6, shorting INL− and INR− to ground.
Conversely, if an inverting input is desired, connect the input
signals to INL− and INR−, and place the jumpers between Pin 1
and Pin 2 of JP5 and JP6, shorting INL+ and INR+ to ground.
Alternatively, single-ended stereo audio can be supplied by
connecting a standard ⅛" stereo plug to the J2 input. In this
case, jumpers must connect INL− and INR− to ground.
OUTPUT SIGNALS
Each channel of the amplifier output is available at two 2-pin
0.100" headers. The speakers are connected in bridge-tied load
(BTL) configuration, and the output pins are labeled with their
polarity; for example, OUTL+ 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 SSM2380 evaluation board to allow proper
measurement of key parameters such as SNR and THD.
The top layer of the PCB contains the footprints necessary for a
ferrite bead-based EMI filter configuration, whereas the bottom
layer of the PCB contains the footprints for an inductor-based
EM I filter. If EMI filtering is used, only H6 and H7 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 H4 and H5.
SHUTDOWN AND MODE JUMPERS
The 2-pin jumper, JP8, is used to enable and disable the SSM2380
SD
amplifier. Inserting a jumper across JP8 pulls the
SPKVDD supply rail, activating the amplifier. Removing the
jumper from JP8 shuts down both channels of the SSM2380
Rev. 0 | Page 3 of 20
so that minimal current (about 20 nA) is drawn from the
power supply.
pin to the
UG-248 Evaluation Board User Guide
09686-004
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
D1 Red 5 V power is supplied over the USB bus
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 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.
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
2
C lines. Otherwise, they should connect the device
rectangular area of Figure 4. If an external I
external I
2
C 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 SSM2380.
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.
2
C lines to the
2
C is used, an
USB POWER SWITCH
The SSM2380 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 SSM2380 software, appears on one pin of the
Cypress microcontroller. This signal controls, Q1 and Q2, 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.
Figure 4. Jumpers as Configured for On-Board I
2
C Operation
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Evaluation Board User Guide UG-248
OPERATING MODES
The SSM2380 has three operating modes: I2C control mode,
ALC mode, and gain select mode. These modes are described
in detail in the SSM2380 data sheet. On the evaluation board,
the 3-pin JP11 jumper allows the user to change between the
available operating modes.
I2C CONTROL MODE
To operate the SSM2380 in I2C control mode, connect JP11 as
shown in Figure 5, connecting the MODE pin to GND. While
2
in I
C control mode, JP9 and JP10 are not used and the jumpers
should be left unconnected.
Figure 5. Jumper Connections for I
ALC MODE
The proper connections for ALC mode are shown in Figure 6.
For this setting, JP11 is open and the middle and bottom pins
of JP9 are shorted. This floats the MODE pin and makes a
connection from the SSM2380 ALCTH pin with Resistor
R24 to GND, setting the SSM2380 ALC limiting range. JP10
is used to activate the radiated emissions reduction mode in
this configuration.
2
C Mode Operation
95
90
85
80
75
70
65
60
OUTPUT VO LTAGE LIMIT (%)
55
50
45
TYPICAL CO NDITION
INTERNAL RESISTOR – 20%
INTERNAL RESISTOR + 20%
100 1k 10k 100k 1M
Figure 7. Output Voltage Limit (V
RESISTOR (Ω)
) vs. RTH
TH
09686-007
GAIN SELECT MODE
The proper connections for gain select mode are shown in
09686-005
Figure 8. A jumper must be inserted on JP11 from center pin
to top pin. JP9 and JP10 allow the user to select the SSM2380
gain from 6 dB to 24 dB. To connect the appropriate gain select
pin to VDD, place a jumper from the center pin to the top pin
of the header. To select GND, simply move the jumper connection to the center pin and bottom pin of the header. A gain
select table shows all possible settings in Table 2. All other
features (ALC, emissions control, and mixer) are deactivated
while the SSM2380 is in gain select mode.
09686-006
Figure 6. Jumper Connections for ALC Mode Operation
The limiting percentage of the ALC feature is determined by the
value of an external resistor, R24, which should be placed on the
secondary side of the board. The resistor value can be calculated
using the curve shown in Figure 7.
Rev. 0 | Page 5 of 20
09686-008
Figure 8. Jumper Connections for Gain Select Mode Operation
Table 2. Gain Select Mode Settings for JP9 and JP10
GAIN1 (JP9) GAIN0 (JP10) Gain Setting
GND GND 6 dB
GND VDD 12 dB
VDD GND 18 dB
VDD VDD 24 dB
UG-248 Evaluation Board User Guide
EVALUATION BOARD SOFTWARE QUICK START PROCEDURES
SSM2380 CONTROL SOFTWARE SETUP
Do not connect the evaluation board until software is installed.
The SSM2380 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/SSM2380.
2. Click Evaluation Boards & Kits.
3. Choose the appropriate Windows version (32-bit or 64-bit)
to download.
4. Extract the SSM2380 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\SSM2380.
SSM2380 USB Driver Installation
Before connecting the SSM2380 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 SSM2380 software. This procedure can be
skipped if the user has previously installed any SigmaStudio
or USBi related drivers from Analog Devices, Inc.)
1. Exit the SSM2380 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 SSM2380.
3. Connect JP4 in the 3.3 V location as shown in the blue-
circled area of Figure 4. 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 was closed. Connect the SSM2380
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. The user must direct the driver installation to the following
path by clicking the Browse tab:
C:\Program Files\Analog Devices Inc\SSM2380\
7. After the path has been properly selected, the user can
continue with the driver installation process. Windows
will properly establish the link between the Cypress USB
controller and the PC.
8. After the previous steps are followed, the user can now run
the SSM2380 control software. The software is located at
the following path: C:\Program Files\Analog Devices
Inc\SSM2380\ SSM2380.exe.
9. For quick access to this software, the installer creates a
shortcut from the SSM2380.exe file to the desktop.
10. If all steps were properly followed, at the top of the
SSM2380 software window, a status message of USBi
Connected appears. If the installation was not successful,
a message of USBi – Cannot Find Device appears.
11. After a successful installation, the
recognizes a connection from the PC to the SSM2380
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 4.
SSM2380 software
Uninstall SSM2380 Control Software
1. Locate the directory where the SSM2380 zipped installer
file was extracted.
2. Double-click setup.exe. Simply select Uninstall to remove
the software from the host PC.
INITIAL SSM2380 HARDWARE SETUP
To allow the SSM2380 software to control the SSM2380
evaluation board, the user 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 to choose an I
supply rail, either 1.8 V or 3.3 V. These two voltages
come from separate on-board LDOs. The SSM2380
control interface works well under either of these I
supply voltage conditions.
2
C interface to the SSM2380. The
2
C VDD, I2C CLK, and I2C DATA.
2
C
2
C
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