dm00065963

AN4171
Application note
25 W mono BTL class-D audio amplifier demonstration board based
on the TDA7491MV
Introduction
The STEVAL-CCA043V1 is a demonstration board designed for the evaluation of the
TDA7491MV mono BTL class-D audio amplifier. This application note provides the board
specifications and a quick-start list for standalone operation. Also included are the
schematic, printed circuit board layout and bill of material.
Due to its high efficiency, the device, assembled in the PSSO36 (slug-down) package, is
capable of dissipating heat without a heatsink. Jumpers on the board allow the configuration
of the amplifier in order to verify the input signal as single-ended or differential and choose
the fixed gain settings. Microswitches are also provided to enable the standby and mute
functions.
The main features of the TDA7491MV include:
■
25 W continuous output power at THD = 10%, RL = 6 Ω, VCC = 16 V
■
20 W continuous output power at THD = 10%, RL = 8 Ω, VCC = 18 V
■
Wide-range, single-supply operation (5 V - 18 V)
■
High efficiency (η = 90%)
■
Four selectable, fixed gain settings (20 dB, 26 dB, 30 dB and 32 dB)
■
Differential inputs to minimize common-mode noise
■
Filterless operation up to 15 W, RL = 8 Ω, VCC =18 V
■
Standby and mute features
■
Short-circuit and thermal overload protections
■
Externally synchronizable
Figure 1.
November 2012
STEVAL-CCA043V1
Doc ID 023710 Rev 1
1/14
www.st.com
Contents
AN4171
Contents
1
2
3
2/14
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2
Demonstration board preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3
Inputs and outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4
Powering up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5
Gain settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.6
Single-ended or differential input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.7
Board schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1
Layout views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2
Design guidelines for PCB schematic and layout . . . . . . . . . . . . . . . . . . . . 9
2.2.1
Dumping network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.2
Main filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.3
Layout recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Doc ID 023710 Rev 1
AN4171
1
Operation
Operation
The TDA7491MV demonstration board specifications are as follows:
1.1
●
Power supply voltage range: 5 V to 18 V
●
Number of channels: 1 BTL (Bridge-Tied Load)
●
Load impedance: 4 Ω to 8 Ω
●
Gain settings: 20 dB, 26 dB, 30 dB, 32 dB
●
Undervoltage protection (UVP): 4.5 V
Power supply
A single power supply is required to feed the TDA7491MV demonstration board via the
connector J2 (see Figure 2).
Connect the positive voltage of the 25 V/3 A DC power supply to the +Vcc pin and the
negative to GND.
Note:
Voltage range 5 V to 18 V = 3 A current capability
1.2
Demonstration board preparation
1.3
1.
Ensure that the power supply is switched OFF.
2.
Connect the regulated power supply, adjusted in the device operating range, to the
connector J2 (observe the polarity).
Inputs and outputs
1.
Connect the loads across the connectors J3 (LEFT) and J4 (RIGHT), the specified
impedance ranges from 6 to 8 Ω.
2.
Connect the analog audio inputs, either differential or single-ended, to the L-input and
R-input RCA plugs (J1).
Table 1.
Input configuration
Input configuration
Jumper J8 (right)
Jumper J9 (left)
Differential
Open
Open
Single-ended
Closed
Closed
Refer to Figure 2: Demonstration board connections on page 4.
Doc ID 023710 Rev 1
3/14
Operation
Figure 2.
AN4171
Demonstration board connections
Dummy
load
STBY
MUTE
Analog
Input
1.4
GND
Vcc
Powering up
Before powering up the demonstration board, ensure that the TDA7491MV is in standby and
mute conditions and the gain is set to the desired value (default 20 dB). Verify also the
dedicated switches and jumpers.
Table 2.
Figure 3.
Standby and mute settings
STBY (S1)
MUTE (S2)
Status
L
L
STBY
L
H
STBY
H
L
MUTE
H
H
PLAY
Standby and mute switches
S1= STBY
L
H
L
H
S2= MUTE
4/14
Doc ID 023710 Rev 1
AN4171
1.5
Operation
Gain settings
Table 3.
Figure 4.
1.6
Configuration of jumpers J5 and J6
Gain 0 (J5)
Gain 1 (J6)
Gain (db)
Open (L)
Open (L)
20
Open (L)
Closed (H)
26
Closed (H)
Open (L)
30
Closed (H)
Closed (H)
32
Jumpers J5 and J6
Single-ended or differential input
Jumper J9 is used to modify the input signal configuration.
Table 4.
Figure 5.
Configuration of jumper J9
Input configuration
Jumper (J9)
Differential
Open
Single-ended
Closed
Jumper J9
Jumper J9
Doc ID 023710 Rev 1
5/14
Operation
AN4171
1.7
Board schematic and bill of material
Figure 6.
STEVAL-CCA043V1 schematic
6/14
Doc ID 023710 Rev 1
AN4171
Table 5.
Package
Operation
Bill of material
Description
Qty
Reference
Manufacturer
C0603
330 pF 50 V NPO ±5%
1
C27
Murata
C0603
1 nF 50 V ±10%
2
C3, C4
Murata
C0603
100 nF 50 V ±10%
8
C5, C6, C8, C9, C10, C24,
C25, C28
Murata
C0603
470 nF 50 V ±10%
2
C1, C2
Murata
C0603
2.2 µF, 16 V ±10%
3
C7, C15, C29
Murata
C0603
1 µF, 16 V, ±10%
2
C16, C17
Murata
E-cap
1000 µF, 25 V, ±10%,
pitch = 5.0 mm
1
C23
C1206
10 µF, 25 V, ±20%, Y5V
4
C30, C31, C32, C33
Murata
Mcap
220 nF, 50 V, ±10% PITCH=5.0mm
1
C26
Murata
R0603
22 ohm, ±10%, 1/16 W
2
R6, R7
Murata
R0603
2.2k ohm, ±10%, 1/16 W
1
R8
Murata
R0603
9.1k ohm, ±10%, 1/16 W
1
R13
Murata
R0603
33k ohm, ±10%, 1/16 W
2
R2, R4
Murata
R0603
39k ohm, ±10%, 1/16 W
1
R3
Murata
R0603
100k ohm, ±10%, 1/16 W
1
R1
Murata
PSSO36
slug-down
TDA7491MV (SSO36) slug-down
1
IC1
STMicroelectronics
Coil 10X10
33 µh 2 A Type:7075P-330M(1)
2
L1, L2
Kwan Sung
RCA-2P
RCA socket 1X2P, type AV2-8.4-4
1
J1
Songcheng
TO92
L4931CZ33, 3V3 regulator
1
IC2
STMicroelectronics
CNN-Terminal 2P, pitch = 5 mm connector terminal
3
J2, J3
Any source
2-way jumper
2P, pitch = 2.5 mm jumper
4
J5, J6, J9
Any source
Slide switch
3P, pitch = 2.5 mm
2
S1, S2
Any source
Rubycon
1. Alternate part MSS1246/MSS1260
Doc ID 023710 Rev 1
7/14
PCB layout
AN4171
2
PCB layout
2.1
Layout views
8/14
Figure 7.
Top view of PCB layout
Figure 8.
Bottom view of PCB layout
Doc ID 023710 Rev 1
AN4171
PCB layout
Figure 9.
Top view of PCB layout - with dimensions
65.0mm
R1.2mm x 3
40.0mm
R1.5mm x 4
2.2
Design guidelines for PCB schematic and layout
2.2.1
Dumping network
The capacitor is mainly intended for high inductive loads and for common-mode noise
attenuation.
Figure 10. Dumping network
C28
100nF
C24
100nF
Doc ID 023710 Rev 1
9/14
PCB layout
2.2.2
AN4171
Main filter
The main filter is an LC Butterworth based filter. The cutoff frequency must be chosen
between the upper limit of the audio band (~20 kHz) and the carrier frequency (310 kHz).
Figure 11. Main filter
Table 6.
10/14
Recommended values
RLOAD
8Ω
6Ω
LLOAD
33 µH
22 µH
CLOAD
220 nF
220 nF
Doc ID 023710 Rev 1
AN4171
2.2.3
PCB layout
Layout recommendations
The following figures illustrate layout recommendations.
Solder the 100 nF bypass capacitor (X7R) as close as possible to the IC VCC pins
(recommended distance to be within 3 mm) in order to avoid spikes generated by the stray
inductance caused by the copper supply lines.
Figure 12. Capacitor soldered as close as possible to VCC pins
Ground pin and Vcc pin of
100nF capacitor should be
directly connected to the
related IC pin
Solder the snubber network as close as possible to the related IC pin.
A voltage spike dangerous for device operation could occur if the snubber network is far
from the output pins. It is recommended that the distance between the snubber network and
the output pins be within 5 mm.
Figure 13. Snubber network soldered as close as possible to relevant IC pin
Snubber
Doc ID 023710 Rev 1
11/14
PCB layout
AN4171
Place the RC filter for the ROSC pin close to the IC.
Figure 14. RC filter
RC filter :
C8,R3
Place the filter capacitor for SVR, VREF, SVCC, VSS and VDDPW close to the IC.
Figure 15. Filter capacitor
VDDS-C5
SVR-C16
SVCC/Vss-C10
Vref-C17
12/14
Doc ID 023710 Rev 1
AN4171
3
Revision history
Revision history
Table 7.
Document revision history
Date
Revision
13-Nov-2012
1
Changes
Initial release.
Doc ID 023710 Rev 1
13/14
AN4171
Please Read Carefully:
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the
right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any
time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such
third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
UNLESS EXPRESSLY APPROVED IN WRITING BY TWO AUTHORIZED ST REPRESENTATIVES, ST PRODUCTS ARE NOT
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY,
DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE
GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any
liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries.
Information in this document supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
© 2012 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America
www.st.com
14/14
Doc ID 023710 Rev 1
Similar pages