1 Introduction
To help the user investigate and evaluate the LM48511SQ performance and capabilities, a fully populated
demonstration board was created. This board is shown in Figure 1. Connected to an external power
supply (3.0V ≤ VDD≤ 5.5V) and a signal source, the LM48511SQ demonstration board easily exercises the
amplifier’s features.
User's Guide
SNAA064C–November 2008–Revised May 2013
AN-1922 LM48511 Evaluation Board
Figure 1. Typical LM48511SQ Demonstration Board
2 Quick Start Guide
Step 1. Apply a 3.0V to 5.5V power supply voltage to the VDD pin with respect to the ground (GND) pin.
Step 2. Set connectors SD_Amp, SS_En Enable, SD_Boost to High. Set FB_SEL to Low which boosts
the regulator output voltage PV1 to about 7.6V.
Step 3. Apply a mono differential input signal into the Audio Input’s two center pins of the 4-pin connector.
Step 4. Apply power. Make measurements.
All trademarks are the property of their respective owners.
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
1
Copyright © 2008–2013, Texas Instruments Incorporated
General Description
3 General Description
The Texas Instruments LM48511 integrates a boost converter with a high efficiency Class D audio power
amplifier to provide 3W continuous power into an 8Ω speaker when operating from a 5V power supply.
When operating from a 3V to 4V power supply, the LM48511 can be configured to drive 1 to 2.5W into an
8Ω load with less than 1% distortion (THD+N). The Class D amplifier features a low noise PWM
architecture that eliminates the output filter, reducing external component count, board area consumption,
system cost, and simplifying design. A selectable spread spectrum modulation scheme suppresses RF
emissions, further reducing the need for output filters. The LM48511’s switching regulator is a currentmode boost converter operating at a fixed frequency of 1MHz. Two selectable feedback networks allow
the LM48511 regulator to dynamically switch between two different output voltages, improving efficiency
by optimizing the amplifier’s supply voltage based on battery voltage and output power requirements. The
LM48511 is designed for use in portable devices, such as GPS, mobile phones, and MP3 players. The
high, 80% efficiency at 5V, extends battery life when compared to boosted Class AB amplifiers.
Independent regulator and amplifier shutdown controls optimize power savings by disabling the regulator
when high output power is not required.
The gain of the LM48511 is set by external resistors, which allows independent gain control from multiple
sources by summing the signals. Output short circuit and thermal overload protection prevent the device
from damage during fault conditions. Superior click and pop suppression eliminates audible transients
during power-up and shutdown.
4 Board Features
The LM48511SQ 3W, Ultra-Low EMI, Filterless, Mono, Class D Audio Power Amplifier with Spread
Spectrum demonstration board has all of the necessary connections using 0.100” headers connectors to
apply the power supply voltage, audio input signals, and audio output (speaker). The amplified audio
signal is only available on the audio output header.
www.ti.com
5 Operating Conditions
Temperature Range: T
Supply Voltage (VDD) 3.0V ≤ VDD≤ ±5.5V
Amplifier Voltage (PV1, V1) 4.8V ≤ PV1≤ ±8.0V
MIN
≤ TA≤ T
MAX
–40°C ≤ TA≤ +85°C
2
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
4
Softstart
19
FB
20
FB_GND0
21
FB_GND1
1
FB_SEL
24
/SD_Boost
5
/SD_Amp
17
VGO-
16
IN+
15
IN-
14
VGO+
LM48511SQ
LS+
LS-
8
12
GND3
22
GND3
23
GND3
SW
SW
VDD
2
3
18
PV1
10
V1
13
6.8 PH
L1
10 PF
CS1
GND3
1 PF
CS2
GND3
1 PF
CS3
GND2
VDD
D1
+
C2
100 PF
GND3
GND2 GND1
+
C3
1 PFC41 PF
2
1
Speaker
100 nF
CSoftstart
GND2
R2
9.31k
R1
4.87k
R4
2.5k
+
+
R3
25.5k
C1
280 pF
GND2
7
GND2
GND1
9
GND1
GND1
11
GND1
SS-EN
6
1
2
3
SS_EN
1
2
3
VDD
GND2
R8
20k
R6
20k
R5
20k
R7
20k
CIN+
180 nF
CIN-
180 nF
GND3
GND2
GND1
GND
1
2
3
FB_SEL
1
2
3
VDD
GND2
1
2
3
SD_Boost
1
2
3
VDD
GND2
GND1 (Class D GND)
GND2 (AGND)
GND3 (Switch GND)
1
2
3
SD_Amp
1
2
3
VDD
GND2
1
2
4
Audio Input
1
2
4
GND2
3
3
1
2
VDD
VDD
GND2
GND2
www.ti.com
6 Application Circuit Schematic
Application Circuit Schematic
7 Connections
Designator Function or Use
Supply Voltage (VDD) The supply voltage operating range is from 3.0V to 5.5V, but the absolute maximum rating is 9V.
Audio Input ended audio source, connect one of the center pins to the adjacent center pin (GND) and connect
Speaker (Audio Output) Connect speaker load across the speaker connector.
SD_Amp
SS_EN Enable
SD_Boost
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Figure 2. Typical LM48511 Audio Amplifier Application Circuit
Table 1. LM48511 Demonstration Board Connections
Connect a differential audio source to the two center pins of the Audio Input connector. For a singlethe audio source to the remaining center pin.
Set SD_AMP Low to disable the Class D amplifier.
Set SD_AMP High to enable the Class D amplifier.
Set SS_EN Low to enable Fixed frequency (FF) mode.
Set SS_EN High to enable Spread Spectrum (SS) mode.
Set SD_Boost Low to disable the boost regulator.
Set SD_Boost High to enable the boost regulator.
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
3
10
1
0.1
0.01
10m 100m 1 5
OUTPUT POWER (W)
THD+N (%)
SPREAD SPECTRUM
FIXED FREQUENCY
10
0.01
0.1
1
20 200 2k 20k
FREQUENCY (Hz)
THD+N (%)
0.001
SPREAD SPECTRUM, C
IN
= 1 PF
FIXED FREQUENCY, C
IN
= 1 PF
SPREAD SPECTRUM,
C
IN
= 180 nF
FIXED FREQUENCY,
C
IN
= 180 nF
10
0.01
0.1
1
20 200 2k 20k
FREQUENCY (Hz)
THD+N (%)
0.001
FIXED FREQUENCY
SPREAD SPECTRUM
10
0.01
0.1
1
20 200 2k 20k
FREQUENCY (Hz)
THD+N (%)
0.001
FIXED FREQUENCY
SPREAD SPECTRUM
Typical Performance Characteristics
Table 1. LM48511 Demonstration Board Connections (continued)
Designator Function or Use
Set the FB_SEL High for:
PV1 = VFB {1 + [25.5kΩ / 4.87kΩ]}
FB_SEL
where VFB= 1.23V
Set the FB_SEL Low for:
PV1 = VFB {1 + [25.5kΩ /9.31kΩ]}
where VFB= 1.23V
8 Typical Performance Characteristics
THD+N vs Frequency THD+N vs Frequency
PO= 2W, filter = 22kHz, PV1= 7.8V PO= 500mW, filter = 22kHz, PV1= 4.8V
VDD= 5V, RL= 8Ω VDD= 3.6V, RL= 8Ω
www.ti.com
THD+N vs Frequency THD+N vs Output Power
VDD= 3V, RL= 8Ω VDD= 5V, RL= 8Ω
PO= 1.5W, filter = 22kHz, PV1= 7V PO= 1.5W, f = 1kHz, filter = 22kHz, PV1= 7.8V
4
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
10
1
0.1
0.01
10m 100m 1 5
OUTPUT POWER (W)
THD+N (%)
3V
5V
3.6V
10
1
0.1
0.01
10m 100m 1 5
OUTPUT POWER (W)
THD+N (%)
4.87 k:
5.35 k:
9.31 k:
10
1
0.1
0.01
10m 100m 1 5
OUTPUT POWER (W)
THD+N (%)
SPREAD SPECTRUM
FIXED FREQUENCY
10
1
0.1
0.01
10m 100m 1 5
OUTPUT POWER (W)
THD+N (%)
SPREAD SPECTRUM
FIXED FREQUENCY
www.ti.com
Typical Performance Characteristics
THD+N vs Output Power THD+N vs Output Power
VDD= 3.6V, RL= 8Ω VDD= 3V, RL= 8Ω
f = 1kHz, filter = 22kHz, PV1= 7V f = 1kHz, filter = 22kHz, PV1= 4.8V
THD+N vs Output Power THD+N vs Output Power
VDD= 3V, 3.6V, 5V, RL= 8Ω VDD= 3.6V, RL= 8Ω
f = 1kHz, filter = 22kHz, R1= 4.87kΩ, FF filter = 22kHz, PV1= 7.8V, PV1= 7V, PV1= 4.8V, FF
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
5
Copyright © 2008–2013, Texas Instruments Incorporated
100
50
40
60
70
90
30
20
1.60
0
OUTPUT POWER (W)
EFFICIENCY (%)
0.2 0.4 0.6 0.8 1.0 1.2 1.4
80
10
0
-20
-40
-60
-80
-100
20 200 2k 20k
FREQUENCY (Hz)
PSRR (dB)
FIXED FREQUENCY
SPREAD SPECTRUM
100
50
40
60
70
90
30
20
4.00
0
OUTPUT POWER (W)
EFFICIENCY (%)
0.5 1.0 1.5 2.0 2.5 3.0 3.5
80
10
100
50
40
60
70
90
30
20
3.00
0
OUTPUT POWER (W)
EFFICIENCY (%)
0.5 1.0 1.5 2.0 2.5
80
10
Typical Performance Characteristics
Boost Amplifier vs Output Power Boost Amplifier vs Output Power
VDD= 5V, RL= 8Ω VDD= 3.6V, RL= 8Ω
f = 1kHz, PV1= 7.8V f = 1kHz, PV1= 7V
Boost Amplifier vs Output Power PSRR vs Frequency
VDD= 3V, RL= 8Ω VDD= 5V, RL= 8Ω
f = 1kHz, PV1= 4.8V V
= 200mVPP, PV1= 7.8V
RIPPLE
www.ti.com
6
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
30
5
2.5 6.03.0 3.5 4.0 4.5 5.0 5.5
15
20
25
10
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SPREAD SPECTRUM
FIXED FREQUENCY
23
5
2.5 6.0
7
9
11
13
15
17
19
21
3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SPREAD SPECTRUM
FIXED FREQUENCY
0
-20
-40
-60
-80
-100
20 200 2k 20k
FREQUENCY (Hz)
PSRR (dB)
SPREAD SPECTRUM
FIXED FREQUENCY
0
-20
-40
-60
-80
-100
20 200 2k 20k
PSRR (dB)
FREQUENCY (Hz)
FIXED FREQUENCY
SPREAD SPECTRUM
www.ti.com
Typical Performance Characteristics
PSRR vs Frequency PSRR vs Frequency
VDD= 3.6V, RL= 8Ω VDD= 3V, RL= 8Ω
V
= 200mVPP, PV1= 7V V
RIPPLE
= 200mVPP, PV1= 4.8V
RIPPLE
Supply Current vs Supply Voltage Supply Current vs Supply Voltage
PV1= 7.8V PV1= 7V
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
7
Copyright © 2008–2013, Texas Instruments Incorporated
POWER DISSIPATION (W)
0 3.5
OUTPUT POWER (W)
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.5 1.0 1.5 2.0 2.5 3.0
1.8
0
POWER DISSIPATION (W)
0 1.6
OUTPUT POWER (W)
0.4 0.6 0.8 1.0 1.2 1.4
0.5
0
0.2
0.4
0.3
0.2
0.1
11
5
2.5 6.03.0 3.5 4.0 4.5 5.0 5.5
6
7
8
9
10
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SPREAD
SPECTRUM
FIXED FREQUENCY
POWER DISSIPATION (W)
0 4.0
OUTPUT POWER (W)
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.5 1.0 1.5 2.0 2.5 3.0 3.5
1.8
0
Typical Performance Characteristics
www.ti.com
Supply Current vs Supply Voltage VDD= 5V, RL= 8Ω
Power Dissipation vs Output Power
PV1= 4.8V PV1= 7.8V, FF
Power Dissipation vs Output Power Power Dissipation vs Output Power
VDD= 3.6V, RL= 8Ω VDD= 3V, RL= 8Ω
PV1= 7V, FF PV1= 4.8V, FF
8
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
100
50
40
60
70
90
30
20
0.40
0
LOAD CURRENT (A)
EFFICIENCY (%)
0.05 0.10 0.15 0.20 0.25 0.30 0.35
80
10
100
50
40
60
70
90
30
20
0.70
0
LOAD CURRENT (A)
EFFICIENCY (%)
0.1 0.2 0.3 0.4 0.5 0.6
80
10
100
50
40
60
70
90
30
20
0.60
0
LOAD CURRENT (A)
EFFICIENCY (%)
0.1 0.2 0.3 0.4 0.5
80
10
www.ti.com
Typical Performance Characteristics
Boost Converter Efficiency Boost Converter Efficiency
vs vs
I
LOAD(DC)
VDD= 5V, PV1= 7.8V VDD= 3.6V, PV1=7V
I
LOAD(DC)
Boost Converter Efficiency
vs
I
LOAD(DC)
VDD= 3V, PV1= 4.8V
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
9
Copyright © 2008–2013, Texas Instruments Incorporated
PCB Layout Guidelines
9 PCB Layout Guidelines
This section provides general practical guidelines for PCB layouts that use various power and ground
traces. Designers should note that these are only “rule-of-thumb” recommendations and the actual results
are predicated on the final layout.
9.1 Power and Ground Circuits
Star trace routing techniques can have a major positive impact on low-level signal performance. Star trace
routing refers to using individual traces that radiate from a signal point to feed power and ground to each
circuit or even device.
9.2 Layout Helpful Hints:
1. Avoid routing traces under the inductor.
2. Use three separate grounds that eventually connect to one point:
(a) Signal or quiet ground (GND2)
(b) Ground for the LM48511 device (GND1)
(c) SW (GND3) (switch ground). This trace for the switch ground carries the heaviest current (3A) and
therefore is the nosiest. Make this trace as wide and short as possible and keep at a distance from
the quiet ground and device ground. Give distance priority to the quiet ground.
10 Bill Of Materials
www.ti.com
Designator Description Footprint Qty Value
Cf1 CHIP CAPACITOR GENERIC CAP 0805 1 470pF
CINA CHIP CAPACITOR GENERIC CAP 1210 1 1μF
CINB CHIP CAPACITOR GENERIC CAP 1210 1 1μF
Co CHIP CAPACITOR GENERIC CAP 1210 1 10μF
Cs1 CHIP CAPACITOR GENERIC CAP 1210 1 2.2μF
Cs2 CHIP CAPACITOR GENERIC CAP 1210 1 4.7μF
D1 SCHOTTKY DIODE DIODE MBR0520 IR 1
L1 IND_COILCRAFT-DO1813P 1 4.7μH
R1 CHIP RESISTOR GENERIC RES 0805 1 41.2K
R2 CHIP RESISTOR GENERIC RES 0805 1 13.3K
RINA CHIP RESISTOR GENERIC RES 0805 1 150K
RINB CHIP RESISTOR GENERIC RES 0805 1 150K
11 Demonstration Board PCB Layout
Figure 3 through Figure 8 shows the different layers used to create the LM48511SQ demonstration board.
Figure 3 is the silkscreen that shows component locations on the board’s top surface. Figure 4 is the
metal Top Layer. Figure 5 is the metal Midlayer 1. Figure 6 is the metal Midlayer 2. Figure 7 is the metal
Bottom Layer. Figure 8 is the silkscreen that shows component locations on the board bottom.
10
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
www.ti.com
Demonstration Board PCB Layout
Figure 3. Top Silkscreen
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
Figure 4. Top Layer
11
Copyright © 2008–2013, Texas Instruments Incorporated
Demonstration Board PCB Layout
www.ti.com
Figure 5. Mid Layer 1
12
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Figure 6. Mid Layer 2
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
www.ti.com
Demonstration Board PCB Layout
Figure 7. Bottom Layer
SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board
Submit Documentation Feedback
Figure 8. Bottom Overlay
13
Copyright © 2008–2013, Texas Instruments Incorporated
Revision History
12 Revision History
Rev Date Description
1.0 11/05/08 Initial release.
1.01 08/05/11 Changed the title of Table 1 from LME49600 to LM48511.
1.02 10/18/12
www.ti.com
Edited Table 1 (Demonstration Board Connections). Edited Figure 2 (Typical LM48511 Audio
Amplifier Circuit).
14
AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
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
Loading...