Texas Instruments | AN-1611 LM48555 Evaluation Board (Rev. A) | User Guides | Texas Instruments AN-1611 LM48555 Evaluation Board (Rev. A) User guides

Texas Instruments AN-1611 LM48555 Evaluation Board (Rev. A) User guides
User's Guide
SNAA041A – April 2007 – Revised May 2013
AN-1611 LM48555 Evaluation Board
1
Quick Start Guide
1.
2.
3.
4.
2
Apply power supply voltage to positive terminal of JU4, and source ground to the negative terminal.
Short the terminals of JU1 to release the device from shutdown mode.
Connect a ceramic speaker, and series resistance load across the output terminals of JU3.
Apply a differential audio signal to the positive and negative terminals of JU2.
Introduction
The LM48555 is an audio power amplifier designed to drive ceramic speakers in portable applications.
The LM48555 outputs15.5VP-P with less than 1% THD + N while operating from a 3.2V power supply. The
LM48555 features differential inputs for improved noise rejection and a low power shutdown mode.
The LM48555 includes advanced click and pop suppression that eliminates audible turn-on and turn-off
transients. Additionally, the integrated boost regulator features a soft start function that minimizes transient
current during power-up. The LM48555 is unity-gain stable and uses external gain-setting resistors.
The LM48555 Evaluation board (Figure 1) allows you to easily evaluate the performance and
characteristics of the LM48555 device. It provides connectors for audio inputs, audio outputs, power
supply, and shutdown control. The ceramic speaker load is not included on the demo board, an external
ceramic speaker plus series resistor is needed for evaluation.
3
Operating Conditions
•
•
Temperature Range -40°C ≤ TA ≤ +85°C
Supply Voltage 2.7V < VDD < 6.5V
All trademarks are the property of their respective owners.
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
AN-1611 LM48555 Evaluation Board
Copyright © 2007–2013, Texas Instruments Incorporated
1
LM48555 Evaluation Board
4
www.ti.com
LM48555 Evaluation Board
Figure 1. LM48555 Evaluation Board
2
AN-1611 LM48555 Evaluation Board
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
Copyright © 2007–2013, Texas Instruments Incorporated
Evaluation Board Schematic
www.ti.com
5
Evaluation Board Schematic
RIN20 k:
Soft Start
CSS
100 nF
CIN470 nF
INRSD
SD
JU1
1 k:
JU4
CF82 pF
RF200 k:
CF+
82 pF
RF+
200 k:
VDD
GND
OUT+
L1
10 PH
LM48555
GND
INPUT
JU2
CS
4.7 PF
OUTPUT
JU3
VDD
OUT-
SW
D1
GND (SW)
CO
10 PF
IN+
RIN+
20 k:
Bootstrap
VAMP
CIN+
470 nF
Figure 2. Evaluation Board Schematic
6
Connectors
The LM48555 evaluation boards features connectors for the audio inputs, audio outputs, power supply,
and shutdown control. The functionality and designators of each connector are specified in Table 1.
Table 1. Connectors
7
Designator
Label
JU1
Shutdown
Function
JU2
Audio Input
JU3
Audio Output
This connector provides a connection to the amplifier outputs. A ceramic speaker load, and
series resistors, should be connected across these terminals.
JU4
Power Supply
This connector provides the power supply connection. Apply an external power supply’s
positive voltage to the pin labeled VDD and the ground source to the pin labeled GND.
This connector is used to control the Shutdown function:
If JU1 is open, then the LM48555 is in Shutdown.
If JU1 is shorted, then the LM48555 is active.
This connector connects the audio input signal to the device inputs. Apply the positive
signal source to the pin labeled “+” and the negative signal source to the pin labeled “-”.
Bill of Materials
Table 2. Bill of Materials
Designator
Part Description
D2
Diode Schottky 20V 0.5A SOD123
L1
INDUCTOR 10μH 20% SMD
CIN+, CIN-
Capacitor Ceramic 0.47μF 10V X5R 0402
Manufacturer
Part Number
ON Semi
MBR0520LT1G
Taiyo Yuden
NR3010T100M
Murata
GRM155R61A474KE15D
CO
Capacitor Ceramic 10μF 16V X5R 0805
Taiyo Yuden
EMK212BJ106KG-T
CSS
Capacitor Ceramic 0.1μF 25V X5R 0402
Murata
TMK105BJ104KV-F
Capacitor Ceramic 82pF 50V 5% C0G 0402
Murata
GRM1555C1H820JZ01D
CF+, CFCS
Capacitor Ceramic 4.7μF 16V X5R 0805
Taiyo Yuden
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
EMK212BJ475KG-T
AN-1611 LM48555 Evaluation Board
Copyright © 2007–2013, Texas Instruments Incorporated
3
Evaluation Board Components
www.ti.com
Table 2. Bill of Materials (continued)
Designator
8
Part Description
Manufacturer
Part Number
RF+, RF-
Resistor 200kΩ 1/16W 1% 0402 SMD
Panasonic
ERJ-2RKF2003X
RIN+, RIN-
Resistor 20kΩ 1/16W 1% 0402 SMD
Panasonic
ERJ-2RKF2002X
RSD
Resistor 1.0kΩ 1/16W 1% 0402 SMD
Panasonic
ERJ-2RKF1001X
Evaluation Board Components
Part number and manufacturer information for the components on the LM48555 evaluation board can be
found in the Bill of Materials (Table 2). For more information on component selection refer to the LM48555
datasheet.
9
PCB Layout Guidelines
High frequency boost converters require very careful layout of components in order to get stable operation
and low noise. All components must be as close as possible to the LM4962 device. It is recommended
that a four-layer PCB be used so that internal ground planes are available. See Figure 3 through Figure 8
for demo board reference schematic and layout. Some additional guidelines to be observed:
• Keep the path between L1, D1, and CO extremely short. Parasitic trace inductance in series with D1
and C0 will increase noise and ringing.
• If internal ground planes are available (recommended) use vias to connect directly to ground at the
GND (SW) and GND pins of U1, as well as the negative sides of capacitors CS and CO.
10
General Layout Recommendations
This section provides practical guidelines for PCB layouts. Designers should note that these are only ruleof-thumb recommendations and the actual results will depend heavily on the final layout.
10.1 Power and Ground Circuits
For multi-layer boards, it is important to isolate the switching power and ground trace paths from the
amplifier power and ground trace paths. Star trace routing techniques (bringing individual traces back to a
central point rather than daisy chaining traces together in a serial manner) can have a major impact on
low level signal performance. Star trace routing refers to using individual traces to feed power and ground
to each circuit or even device. This technique will require a greater amount of design time but will not
increase the final price of the board.
10.2 Avoiding Typical Design / Layout Problems
Avoid ground loops or running digital and analog traces parallel to each other (side-by-side) on the same
PCB layer. When traces must cross over each other, do it at 90 degrees. Running digital and analog
traces at 90 degrees to each other from the top to the bottom side as much as possible will minimize
capacitive noise coupling and crosstalk.
11
Micro SMD Wafer Level Chip Scale Package: PCB, Layout, and Mounting
Considerations
Please refer to AN-1112 DSBGA Wafer Level Chip Scale Package (SNVA009) for possible updates to the
μSMD package information.
4
AN-1611 LM48555 Evaluation Board
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
Copyright © 2007–2013, Texas Instruments Incorporated
PCB Layout
www.ti.com
12
PCB Layout
Figure 3. Silkscreen Top
Figure 4. Top Layer
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
AN-1611 LM48555 Evaluation Board
Copyright © 2007–2013, Texas Instruments Incorporated
5
PCB Layout
www.ti.com
Figure 5. Layer 2
Figure 6. Layer 3
6
AN-1611 LM48555 Evaluation Board
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
Copyright © 2007–2013, Texas Instruments Incorporated
PCB Layout
www.ti.com
Figure 7. Bottom Layer
Figure 8. Silkscreen Bottom
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
AN-1611 LM48555 Evaluation Board
Copyright © 2007–2013, Texas Instruments Incorporated
7
Revision Table
13
8
www.ti.com
Revision Table
Rev
Date
Description
1.0
04/03/07
Initial release.
AN-1611 LM48555 Evaluation Board
SNAA041A – April 2007 – Revised May 2013
Submit Documentation Feedback
Copyright © 2007–2013, Texas Instruments Incorporated
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2013, Texas Instruments Incorporated
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising