National Semiconductor LME49600 User Manual

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LME49600 Headphone

Amplifier Evaluation Board

User's Guide

National Semiconductor

Application Note 1768

Kevin Hoskins

February 29, 2008

Quick Start Guide

Apply a ±2.5V to ±17V power supply’s voltage to the respec-

tive “V

”, “GND” and “V

” pins on JU19

Apply a stereo audio signal to the RCA jacks J1 (Right) and

J2 (Left) or jumpers JU1 (Right) and JU17 (Left), observing

the signal input pin and the ground (GND) pin. Though not

typically installed, a stereo signal can also be applied to head-

phone jack HPJ1.

Connect a load to JU14 (Left) and another load to JU15

(Right), observing the signal output pin and the ground (GND)

pin. The stereo signal output is also available on the 1/8”

stereo headphone jack located in the board's “OUTPUT” sec-

tion

Use VR1 to control the output signal amplitude.

Apply power. Make measurements. Plug in a pair of head-

phones. Enjoy.

Introduction

To help the user investigate and evaluate the LME49600's

performance and capabilities, a fully populated demonstration

board was created. Please contact the National Semiconduc-

tor Corporation's Audio Products Group for availability. This

board is shown in Figure 1. Connected to an external power

supply (±2.5V to ±17V ) and a signal source. The LME49600

demonstration board easily demonstrates the amplifier's fea-

tures.

30047312

FIGURE 1. The LME49600/LME49720 Stereo Headphone Amplifier Demonstration Board

300473

www.national.com

LME49600 Headphone Amplifier Evaluation Board User's Guide

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Summary of LME49600

Page 1
Lme49600 headphone amplifier evaluation board user's guide national semiconductor application note 1768 kevin hoskins february 29, 2008 quick start guide apply a ±2.5v to ±17v power supply’s voltage to the respec- tive “v + ”, “gnd” and “v - ” pins on ju19 apply a stereo audio signal to the rca jack...
Page 2
General description the lme49600 is a high performance, low distortion high fi- delity 250ma audio buffer. Whereas there are many uses for the lme49600, this application note describes a headphone amplifier circuit and associated demonstration board. De- signed for use inside an operational amplifie...
Page 3
Connections connecting to the world is accomplished through a combina- tion of rca jacks, 1/8” stereo headphone jacks and 0.100” headers on the lme49600 demonstration board. The func- tions of the different headers, 1/8” headphone jacks and rca jacks are detailed in table 1. Table 1. Lme49600 demons...
Page 4
Bill of materials refdes part description value tolerance rating package type manufacturer and part number bat1– bat2 9v battery terminal (male & female) [not installed] keystone 593 (female) & 594 (male) c1 – c8 mulitylayer ceramic capacitor 1.0μf ±20% 25v 805 tdk c2012x5r1e105m c9 c10, c23 – c24 t...
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Demonstration board pcb layout figures 3 through 6 show the different layers used to create the lme49600 demonstration board. Figure 3 is the silkscreen that shows parts location. Figure 4 is the top layer. Figure 5 is the bottom layer. Figure 6 is the bottom silkscreen layer. 30047316 figure 3. Top...
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30047313 figure 5. Bottom layer 30047314 figure 6. Bottom silk layer www.National.Com 6 an-1768.
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Typical performance 30047360 figure 7: thd+n vs output power lme49720/lme49600 headphone amplifier into (from top to bottom at 0.1mw): 16 Ω, 32Ω, 64Ω, 300Ω (v s = ±3v, f = 100hz, 22hz ≤ bw ≤ 22khz) 30047361 figure 8: thd+n vs output power lme49720/lme49600 headphone amplifier into (from top to botto...
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30047363 figure 13: thd+n vs output power lme49720/lme49600 headphone amplifier into (from top to bottom at 0.1mw): 16 Ω, 32Ω, 64Ω, 300Ω (v s = ±3v, f = 10khz, 400hz ≤ bw ≤ 80khz) 30047364 14: thd+n vs output power lme49720/lme49600 headphone amplifier into (from top to bottom at 20mw): 16 Ω, 32Ω, 6...
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Revision history rev date description 1.0 02/29/08 initial release. 9 www.National.Com an-1768.
Page 10: Notes
Notes an-1768 lme49600 headphone amplifier evaluation board user's guide for more national semiconductor product information and proven design tools, visit the following web sites at: products design support amplifiers www.National.Com/amplifiers webench www.National.Com/webench audio www.National.C...