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LM48511 Evaluation Board
User's Guide

National Semiconductor
Application Note 1922
Allan Soriano
November 5, 2008

Quick Start Guide

Apply a 3.0V to 5.5V power supply voltage to the VDD pin with
respect to the ground (GND) pin.
Set connectors SD_Amp, SS_En Enable, SD_Boost to High.
Set FB_SEL to Low (FB_SEL0) which boosts the regulator
output voltage PV1 to about 7.6V.
Apply a mono differential input signal into the Audio Input’s
two center pins of the 4-pin connector.
Apply power. Make measurements.

Introduction

To help the user investigate and evaluate the LM48511SQ
performance and capabilities, a fully populated demonstration
board was created. Please contact National Semiconductor
Corporation’s Audio Products Group for availability. 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.

30085503

FIGURE 1. Typical LM48511SQ Demonstration Board

© 2008 National Semiconductor Corporation

300855

www.national.com

LM48511 Evaluation Board User's Guide

AN-1922

Summary of Contents for LM48511

Page 1: ...s of the 4 pin connector Apply power Make measurements Introduction To help the user investigate and evaluate the LM48511SQ performance and capabilities a fully populated demonstration board was created Please contact National Semiconductor Corporation s Audio Products Group for availability This board is shown in Figure 1 Connected to an external power supply 3 0V VDD 5 5V and a signal source the...

Page 2: ...ements The LM48511 is designed for use in portable devices such as GPS mobile phones and MP3 players The high 80 effi ciency 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 a...

Page 3: ...Schematic 30085504 FIGURE 2 Typical LM48511 Audio Amplifier Application Circuit 3 www national com AN 1922 ...

Page 4: ...here VFB 1 23V When LOW FB_SEL1 the regulator output voltage PV1 is as follows PV1 VFB 1 25 5kΩ 9 31kΩ where VFB 1 23V 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 recommen dations and the actual results are predicated on the final layout POWER AND GROUND CIR...

Page 5: ... 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 5 www national com AN 1922 ...

Page 6: ...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 30085508 FIGURE 3 Top Silkscreen 30085507 FIGURE 4 Top Layer www national com 6 AN 1922 ...

Page 7: ...30085505 FIGURE 5 Mid Layer 1 30085506 FIGURE 6 Mid Layer 2 7 www national com AN 1922 ...

Page 8: ...30085501 FIGURE 7 Bottom Layer 30085502 FIGURE 8 Bottom Overlay www national com 8 AN 1922 ...

Page 9: ...lter 22kHz PV1 4 8V 30085519 THD N vs Frequency VDD 3V RL 8Ω PO 1 5W filter 22kHz PV1 7V 30085520 THD N vs Output Power VDD 5V RL 8Ω PO 1 5W f 1kHz filter 22kHz PV1 7 8V 30085521 THD N vs Output Power VDD 3 6V RL 8Ω f 1kHz filter 22kHz PV1 7V 30085522 THD N vs Output Power VDD 3V RL 8Ω f 1kHz filter 22kHz PV1 4 8V 30085523 9 www national com AN 1922 ...

Page 10: ...V1 7 8V PV1 7V PV1 4 8V FF 30085525 Boost Amplifier vs Output Power VDD 5V RL 8Ω f 1kHz PV1 7 8V 30085526 Boost Amplifier vs Output Power VDD 3 6V RL 8Ω f 1kHz PV1 7V 30085527 Boost Amplifier vs Output Power VDD 3V RL 8Ω f 1kHz PV1 4 8V 30085528 PSRR vs Frequency VDD 5V RL 8Ω VRIPPLE 200mVPP PV1 7 8V 30085529 www national com 10 AN 1922 ...

Page 11: ...3V RL 8Ω VRIPPLE 200mVPP PV1 4 8V 30085531 Supply Current vs Supply Voltage PV1 7 8V 30085532 Supply Current vs Supply Voltage PV1 7V 30085533 Supply Current vs Supply Voltage PV1 4 8V 30085534 Power Dissipation vs Output Power VDD 5V RL 8Ω PV1 7 8V FF 30085535 11 www national com AN 1922 ...

Page 12: ...sipation vs Output Power VDD 3V RL 8Ω PV1 4 8V FF 30085537 Boost Converter Efficiency vs ILOAD DC VDD 5V PV1 7 8V 30085538 Boost Converter Efficiency vs ILOAD DC VDD 3 6V PV1 7V 30085539 Boost Converter Efficiency vs ILOAD DC VDD 3V PV1 4 8V 30085540 www national com 12 AN 1922 ...

Page 13: ...Revision History Rev Date Description 1 0 11 05 08 Initial release 13 www national com AN 1922 ...

Page 14: ...NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS BUYERS SHOULD PROVIDE ADEQUATE DESIGN TESTING AND OPERATING SAFEGUARDS EXCEPT AS PROVIDED IN NATIONAL S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS NATIO...

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