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
© 2008 National Semiconductor Corporation
300473
www.national.com
LME49600 Headphone Amplifier Evaluation Board User's Guide
AN-1768
