Connections
7
Connections
Connecting to the world is accomplished through a combination of RCA jacks, 1/8” stereo headphone
jacks and 0.100” headers on the LME49600 demonstration board. The functions of the different headers,
1/8” headphone jacks and RCA jacks are detailed in
Table 1. LME49600 Demonstration Board Connections
Designator
Function or Use
JU17
This is the connection to the amplifier’s left channel input. Apply an external signal source’s positive
voltage to the JU17 pin labeled “LT IN” and the signal source’s ground signal to the pin labeled “GND.”
J2
This is an RCA connector that parallels the pins on JU17.
HPJ1
Stereo, 1/8” headphone jack. Used for stereo signal input. Left channel input is on the tip connector and
the right channel input is on the ring connector. Ground is on the sleeve connector.
J1
This is an RCA connector that parallels the pins on JU1.
JU1
This is the connection to the amplifier’s right channel input. Apply an external signal source’s positive
voltage to the JU1 pin labeled “RT IN” and the signal source’s ground signal to the pin labeled “GND.”
JU19
Power supply connection. Connect an external split power supply’s voltage source ±2.5V to ±17V to the
JU19 pin labeled (“V+” and “V-”)” and the supply’s ground source to the pin labeled “GND.”
JU14
This is the connection to the amplifier’s single-ended, ground-referenced left channel output. Connect
the JU14 pin labeled “LT OUT” and the pin labeled “GND” to the positive and ground inputs,
respectively, of an external signal measurement device. JU14’s pin labeled “LT OUT” corresponds to the
headphone jack’s “tip” connection. J5’s pin labeled “GND“ corresponds to the headphone jack’s “sleeve”
(or ground) connection.
HPJ2
Stereo, 1/8” headphone jack. Used for stereo signal output. Left channel output is on the tip connector
and the right channel output is on the ring connector. Ground is on the sleeve connector.
JU15
This is the connection to the amplifier’s ground-referenced right channel output. Connect the JU15 pin
labeled “RT OUT” and the pin labeled “GND” to the positive and ground inputs, respectively, of an
external signal measurement device. JU15’s pin labeled “RT OUT” corresponds to the headphone jack’s
“ring” connection. J4’s pin labeled “GND“ corresponds to the headphone jack’s “sleeve” (or ground)
connection.
JU4, JU6
These connections allow monitoring the left and right channel DC servo outputs, respectively.
8
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.
8.1
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.
4
AN-1768 LME49600 Headphone Amplifier Evaluation Board
SNAA052A – February 2008 – Revised May 2013
Copyright © 2008–2013, Texas Instruments Incorporated
