CRD4412A
2 x 15 W CS4412A Digital Power Stage Reference Design
Features
Pre-Configured for Stereo Full-Bridge
Operation
– Delivers 15 W/Ch into 8
Ω
at <0.5%
THD+N
Easily Configurable for Mono Parallel Full-
Bridge Operation
– Delivers 30 W into 4
Ω
at <10% THD+N
Directly Connects to CRD4525 Digital Amplifier
Reference Design
– Implements a 2.1 Configuration
Flexible I/O Provided
– PWM Logic Level Signal Inputs
– CS4412A Error and Warning Signals
Operates from +8 V to +18 V and +3.3 V
Demonstrates Recommended Layout and
Grounding Arrangements
Implements Recommended PWM Output
Filtering
Description
The CRD4412A demonstrates the CS4412A digital am-
plifier power stage. This reference design is pre-
configured as a two-channel full-bridge power stage
which delivers 15 W per channel into 8
Ω
loads using a
single +18 V supply. The design can be easily config-
ured to operate as a single channel parallel full-bridge
power stage capable of delivering 30 W into a 4
Ω
load
from an +18 V supply. The CRD4412A can be powered
from +8 V to +18 V.
The CRD4412A is designed to operate in conjunction
with the CRD4525. When connected, the combination
implements a 2.1 configuration with the CRD4412A op-
erating in mono parallel full-bridge mode.
The CRD4412A can also be operated without an at-
tached CRD4525. In this configuration, all input/output
connections are achieved through the CRD4412 inter-
face header.
The PWM audio power outputs are routed through an
inductor/capacitor 2
nd
order low-pass filter (LPF) to re-
move high-frequency components from the output
signal, effectively converting it from digital to analog.
ORDERING INFORMATION
CRD4412A
CS4412A Reference Design
CRD4412 Interface Header
Mono
Parallel
Full-Bridge
Right PWM
Left PWM
Stereo
Full-Bridge
Over Current Error
Under Voltage/Temp Error
Thermal Warning
Power
Reset
CS4412A
Output
Filter
http://www.cirrus.com
Copyright
©
Cirrus Logic, Inc. 2007
(All Rights Reserved)
Speaker Connector
MAY '07
DS786RD1
Output
Filter
CRD4412A
TABLE OF CONTENTS
1. SYSTEM OVERVIEW ............................................................................................................................. 3
1.1 Power ............................................................................................................................................... 3
1.2 CS4412A Digital Amplifier Power Stage .......................................................................................... 3
1.3 External Data Headers ..................................................................................................................... 3
1.4 Stereo/Mono Selection ..................................................................................................................... 3
1.5 Speaker Outputs .............................................................................................................................. 4
2. OPERATING INSTRUCTIONS ............................................................................................................... 5
2.1 Operation with CRD4525 ................................................................................................................. 5
2.2 Stand-Alone Operation .................................................................................................................... 5
3. GROUNDING AND POWER SUPPLY DECOUPLING .......................................................................... 6
3.1 Power Supply Decoupling ................................................................................................................ 6
3.2 Electromagnetic Interference (EMI) ................................................................................................. 6
3.2.1 Suppression of EMI at the Source ........................................................................................... 6
4. SYSTEM CONNECTIONS AND JUMPERS ........................................................................................... 7
5. CRD SCHEMATICS ................................................................................................................................ 8
6. CRD LAYOUT ...................................................................................................................................... 10
7. PARALLEL FULL-BRIDGE PERFORMANCE PLOTS ....................................................................... 15
8. STEREO FULL-BRIDGE PERFORMANCE PLOTS ............................................................................ 21
9. REVISION HISTORY ............................................................................................................................ 27
LIST OF FIGURES
Figure 1. Stereo Full-Bridge Speaker Terminal Configuration .................................................................... 4
Figure 2. Mono Parallel Full-Bridge Speaker Terminal Configuration ......................................................... 4
Figure 3. CS4412A - Schematic Page 1 ..................................................................................................... 8
Figure 4. Power Outputs - Schematic Page 2 ............................................................................................. 9
Figure 5. Silkscreen Top ........................................................................................................................... 10
Figure 6. Top-Side Copper Layer .............................................................................................................. 11
Figure 7. Inner Copper Layer 1 ................................................................................................................. 12
Figure 8. Inner Copper Layer 2 ................................................................................................................. 13
Figure 9. Bottom-Side Copper Layer ........................................................................................................ 14
Figure 10. Frequency Response in Parallel Full-Bridge Configuration ..................................................... 15
Figure 11. THD+N vs Power in Parallel Full-Bridge Configuration ........................................................... 16
Figure 12. THD+N vs Frequency in Parallel Full-Bridge Configuration ..................................................... 17
Figure 13. FFT at -60dB Input in Parallel Full-Bridge Configuration ......................................................... 18
Figure 14. FFT at 0dB Input in Parallel Full-Bridge Configuration ............................................................ 19
Figure 15. Inter-Modulation Distortion of 19 kHz + 20 kHz in Parallel Full-Bridge Configuration .............. 20
Figure 16. Frequency Response in Stereo Full-Bridge Configuration ....................................................... 21
Figure 17. THD+N vs Power in Stereo Full-Bridge Configuration ............................................................. 22
Figure 18. THD+N vs Frequency in Stereo Full-Bridge Configuration ...................................................... 23
Figure 19. FFT at -60dB Input in Stereo Full-Bridge Configuration ........................................................... 24
Figure 20. FFT at 0dB Input in Stereo Full-Bridge Configuration .............................................................. 25
Figure 21. Inter-Modulation Distortion of 19 kHz + 20 kHz in Stereo Full-Bridge Configuration ............... 26
LIST OF TABLES
Table 1. System Connections ..................................................................................................................... 7
Table 2. System Headers ............................................................................................................................ 7
Table 3. CRD4412 Interface Header Signal Assignments .......................................................................... 7
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DS786RD1
CRD4412A
1. SYSTEM OVERVIEW
The CRD4412A reference design is an excellent means for evaluating the CS4412A 30 W digital amplifier power
stage. The board is designed to connect directly to the CRD4525 digital amplifier reference design for easy evalu-
ation. Alternatively, the CRD4412A may be used alone with all logic-level and power connections made through the
CRD4412 interface header.
The CRD4412A schematic set is shown in
Figure 3
and
Figure 4.
See the CRD4525 data sheet for more information
about the features and connections of the CRD4525.
1.1
Power
Power (VD, VP) must be supplied to the evaluation board through the CRD4412 interface header (J2). All
voltage inputs must be referenced to ground, also provided through the CRD4412 interface header.
See the
CRD4412 Interface Header Signal Assignments
table on
page 7
for signal-to-pin assignments.
WARNING:
Please refer to the CS4412A data sheet for allowable voltage levels.
1.2
CS4412A Digital Amplifier Power Stage
The CS4412A is a 30 W quad half-bridge digital amplifier power stage. A complete description of the
CS4412A is included in the CS4412A product data sheet.
1.3
External Data Headers
The evaluation board has been designed to allow interfacing with external systems via headers J2, J4, and
J6.
Figure 3
shows the headers’ electrical connections.
The 20-pin, 2-column header, J2, is included to interface with the CRD4525 digital amplifier reference de-
sign and to interface with external sources when a CRD4525 is not connected. All necessary signals, power,
and ground are presented on this header. See
Figure 3
for complete connectivity information.
The 4-pin, 2-column header, J4, provides access to the CS4412A’s thermal warning signal and the
CS4525’s DLY_SDIN/EX_TWR signal. When a CRD4525 is attached, a shunt can be placed across these
signals to deliver the CS4412A’s thermal warning signal to the CS4525’s external thermal warning input.
Alternatively, this header can be used to connect the CS4412A’s thermal warning output to another device
and to drive an external serial audio data source into the CS4525. A single ground column is provided to
maintain signal integrity in this configuration.
The 4-pin, 2-column header, J6, provides access to the CS4412A’s over-current error signals and the
CS4525’s DLY_SDOUT signal. When a CRD4525 is attached, this header can be used to connect the
CS4412A’s over-current error signals to another device and to connect the CS4525’s delay serial audio data
output to an external device. A single ground column is provided to maintain signal integrity in this configu-
ration.
1.4
Stereo/Mono Selection
A 3-pin header (J1) is included to select between stereo and mono operation. The position of the shunt
placed across this header determines whether discrete PWM signals are routed to the full-bridge input pairs
or whether a single PWM signal is routed to both full-bridge input pairs.
It should be noted that when mono mode is selected, the outputs may be wired in parallel to achieve parallel
full-bridge operation. See
Section 1.5
for more information.
DS786RD1
3
CRD4412A
1.5
Speaker Outputs
By default, the CS4412A power outputs are configured for stereo full-bridge operation. The outputs are rout-
ed through a 2
nd
order low-pass filter to remove high-frequency content from the output signals and then
presented at the speaker wire crimp terminals (J5). The output filters are optimized for 8
Ω
speaker loads.
The speaker terminal connections are shown below.
Right +
Right -
Left +
Left -
Figure 1. Stereo Full-Bridge Speaker Terminal Configuration
When the CS4412A is configured for mono operation via J1, the outputs must be connected in parallel as
shown below. One wire is used to connect between the red terminals, and another is used to connect be-
tween the black terminals. This parallel connection adjusts the characteristic of the output filters, effectively
optimizing them for 4
Ω
speaker loads.
Mono +
Mono -
Figure 2. Mono Parallel Full-Bridge Speaker Terminal Configuration
4
DS786RD1
CRD4412A
2. OPERATING INSTRUCTIONS
The CRD4412A is designed to connect directly to the CRD4525 digital power amplifier reference design and
to interface with external signal sources. See the following sections for operation details with and without a
CRD4525.
Note that the CRD4412A and CRD4525 must be connected and disconnected from one another while pow-
er is not applied to the CRD4525.
2.1
Operation with CRD4525
When the CRD4412A is attached to a CRD4525 via the CRD4412A interface header and the CRD4525
FlexGUI is launched, the CS4525 is automatically configured to enable its bass manager and route the sub-
woofer channel to the CRD4412A. The CRD4412A amplifies the subwoofer signal in mono parallel full-
bridge mode. Together, the CRD4412A and CRD4525 implement a 2.1 configuration.
To operate the CRD4412A and CRD4525 in this configuration:
1. Download and install the FlexGUI software from
www.cirrus.com/msasoftware.
2. Connect the CRD4412A to the CRD4525 via the CRD4412A interface header.
3. Connect the CRD4525 to a host PC using the supplied USB cable.
4. Connect the 8
Ω
stereo speakers to the speaker terminals on the CRD4525.
5. Wire the two red-terminal speaker outputs together on the CRD4412A as shown in
Figure 2.
6. Wire the two black-terminal speaker output together on the CRD4412A as shown in
Figure 2.
7. Connect the 4
Ω
mono subwoofer between the red and black speaker terminals on the CRD4412A.
8. Place a shunt across pins 2 and 3 of J1 to select mono mode.
9. Place a shunt across pins 1 and 2 of J4 to route the CS4412A thermal warning signal to the CS4525
external thermal warning input.
10. Connect an input source to the S/PDIF or analog input connectors.
11. Plug the input to the +18 V power supply (included with the CRD4525) into an available power outlet.
12. Plug the output of the +18 V power supply into the power input connector on the CRD4525.
13. Launch the FlexGUI software and select the CRD4525 + CRD4412A combination from the board se-
lection list if necessary.
The GUI will load and be displayed.
14. Un-check the “Power Down CS4525” check box to power-up the CS4525.
In this state, the CRD4525
and CRD4412A will convert and amplify the content present on the optical S/PDIF input.
2.2
Stand-Alone Operation
The CRD4412A may be operated alone, without a connected CRD4525. In this mode of operation, all sig-
nals and power are supplied to the CRD4412A through the CRD4412A interface header.
To operate the CRD4412A in this configuration:
1. Connect ground to one of these pins: 7, 9, 11, 13, 15, or 16 of J2.
2. Connect a +3.3 V source to pin 2 of J2, but do not apply power.
3. Connect a +8 V to +18 V source to one of these pins: 17, 18, 19, or 20 of J2, but do not apply power.
4. Connect a reset input signal to pin 14 of J2 and drive it low.
5. Connect logic-level PWM input signals to pins 8 and 10 of J2. For mono mode, it is only necessary to
connect a PWM input signal to pin 10 of J2; pin 8 can be grounded.
WARNING:
Pins 8 and 10 of J2, the PWM input signals, must never be left floating.
6. Place a shunt across 2 pins of J1 to select stereo or mono mode as desired.
7. Connect the outputs and speaker load as discussed in
Section 1.5 on page 4.
8. Apply +3.3 V and +8 V to +18 V power.
DS786RD1
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