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User's Guide

SNAA064C–November 2008–Revised May 2013

AN-1922 LM48511 Evaluation Board

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 ≤ V

≤ 5.5V) and a signal source, the LM48511SQ demonstration board easily exercises the

amplifier’s features.

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.

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SNAA064C–November 2008–Revised May 2013 AN-1922 LM48511 Evaluation Board

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Summary of content (15 pages)

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User's Guide SNAA064C – November 2008 – Revised May 2013 AN-1922 LM48511 Evaluation Board 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. Figure 1. Typical LM48511SQ Demonstration Board 2 Quick Start Guide Step 1.
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General Description 3 www.ti.com 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).
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Application Circuit Schematic www.ti.com Application Circuit Schematic VDD 20 21 GND2 1 VDD 24 5 17 GND2 Audio Input 1 1 GND2 2 2 3 3 4 GND2 4 CIN+ R5 20k CIN- R7 180 nF 20k 16 15 14 GND1 GND 2 3 GND3 GND1 22 GND3 23 FB_GND0 FB_GND1 FB_SEL V1 LM48511SQ /SD_Boost PV1 13 10 /SD_Amp VGO- LS+ 8 Speaker 2 IN+ INVGO+ VDD SS_EN 1 GND2 C4 1 PF 3 GND3 R8 20k GND2 GND3 FB 6 180 nF R6 20k Softstart LS- GND2 4 19 C3 1 PF 12 1 7 + R2 9.
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Typical Performance Characteristics www.ti.com Table 1. LM48511 Demonstration Board Connections (continued) Designator Function or Use Set the FB_SEL High for: PV1 = VFB {1 + [25.5kΩ / 4.87kΩ]} where VFB = 1.23V FB_SEL 8 Set the FB_SEL Low for: PV1 = VFB {1 + [25.5kΩ /9.31kΩ]} where VFB = 1.23V Typical Performance Characteristics THD+N vs Frequency VDD = 3.6V, RL = 8Ω PO = 500mW, filter = 22kHz, PV1 = 4.
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Typical Performance Characteristics www.ti.com THD+N vs Output Power VDD = 3.6V, RL = 8Ω f = 1kHz, filter = 22kHz, PV1 = 7V THD+N vs Output Power VDD = 3V, RL = 8Ω f = 1kHz, filter = 22kHz, PV1 = 4.8V 10 10 THD+N (%) 1 1 THD+N (%) FIXED FREQUENCY SPREAD SPECTRUM 0.1 0.01 10m FIXED FREQUENCY SPREAD SPECTRUM 0.1 100m 1 0.01 10m 5 OUTPUT POWER (W) 100m 1 5 OUTPUT POWER (W) THD+N vs Output Power VDD = 3V, 3.6V, 5V, RL = 8Ω f = 1kHz, filter = 22kHz, R1 = 4.
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Typical Performance Characteristics www.ti.com Boost Amplifier vs Output Power VDD = 3.6V, RL = 8Ω f = 1kHz, PV1 = 7V 100 100 90 90 80 80 70 70 EFFICIENCY (%) EFFICIENCY (%) Boost Amplifier vs Output Power VDD = 5V, RL = 8Ω f = 1kHz, PV1 = 7.8V 60 50 40 30 60 50 40 30 20 20 10 10 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 4.0 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT POWER (W) OUTPUT POWER (W) Boost Amplifier vs Output Power VDD = 3V, RL = 8Ω f = 1kHz, PV1 = 4.
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Typical Performance Characteristics www.ti.com PSRR vs Frequency VDD = 3V, RL = 8Ω VRIPPLE = 200mVPP, PV1 = 4.8V 0 0 -20 -20 -40 PSRR (dB) PSRR (dB) PSRR vs Frequency VDD = 3.6V, RL = 8Ω VRIPPLE = 200mVPP, PV1 = 7V FIXED FREQUENCY -60 SPREAD SPECTRUM -40 -60 SPREAD SPECTRUM -80 -80 -100 20 200 2k 20k FIXED FREQUENCY -100 20 200 FREQUENCY (Hz) 2k 20k FREQUENCY (Hz) Supply Current vs Supply Voltage PV1 = 7.
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Typical Performance Characteristics www.ti.com Power Dissipation vs Output Power VDD = 5V, RL = 8Ω PV1 = 7.8V, FF Supply Current vs Supply Voltage PV1 = 4.8V 11 1.8 1.6 POWER DISSIPATION (W) SUPPLY CURRENT (mA) 10 SPREAD SPECTRUM 9 8 7 6 3.0 3.5 4.0 4.5 1.2 1.0 0.8 0.6 0.4 0.2 FIXED FREQUENCY 5 2.5 1.4 5.0 5.5 0 6.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT POWER (W) SUPPLY VOLTAGE (V) Power Dissipation vs Output Power VDD = 3.
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Typical Performance Characteristics www.ti.com Boost Converter Efficiency vs ILOAD(DC) VDD = 3.6V, PV1 =7V 100 100 90 90 80 80 70 70 EFFICIENCY (%) EFFICIENCY (%) Boost Converter Efficiency vs ILOAD(DC) VDD = 5V, PV1 = 7.8V 60 50 40 30 60 50 40 30 20 20 10 10 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 0.1 LOAD CURRENT (A) 0.2 0.3 0.4 0.5 0.6 LOAD CURRENT (A) Boost Converter Efficiency vs ILOAD(DC) VDD = 3V, PV1 = 4.8V 100 90 EFFICIENCY (%) 80 70 60 50 40 30 20 10 0 0 0.
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PCB Layout Guidelines 9 www.ti.com 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.
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Demonstration Board PCB Layout www.ti.com Figure 3. Top Silkscreen Figure 4.
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Demonstration Board PCB Layout www.ti.com Figure 5. Mid Layer 1 Figure 6.
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Demonstration Board PCB Layout www.ti.com Figure 7. Bottom Layer Figure 8.
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Revision History 12 14 www.ti.com Revision History Rev Date 1.0 11/05/08 Initial release. Description 1.01 08/05/11 Changed the title of Table 1 from LME49600 to LM48511. 1.02 10/18/12 Edited Table 1 (Demonstration Board Connections). Edited Figure 2 (Typical LM48511 Audio Amplifier Circuit).
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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.