2024年4月27日发(作者：顿芷琪)
LME49600 Headphone Amplifier Evaluation Board User's Guide
LME49600 Headphone
Amplifier Evaluation Board
User's Guide
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
National Semiconductor
Application Note 1768
Kevin Hoskins
February 29, 2008
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
AN-1768
© 2008 National Semiconductor
A
N
-
1
7
6
8
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 amplifier’s feedback loop,
it increases output current, improves capacitive load drive,
and eliminates thermal feedback.
The LME49600 offers a pin-selectable bandwidth: a low cur-
rent, 110MHz bandwidth mode that consumes 8mA and a
wide 180MHz bandwidth mode that consumes 15mA. In both
modes the LME49600 has a nominal 2000V/μs slew rate.
Bandwidth is easily adjusted by either leaving the BW pin un-
connected, connecting a resistor between the BW pin and the
V
EE
pin or connecting the BW pin directly to the V
EE
pin.
The LME49600 is fully protected through internal current limit
and thermal shutdown.
Operating Conditions
■
Temperature Range
■
Amplifier Power
Supply Voltage
–40°C
≤
T
A
≤
85°C
2.5V
≤
V
S
±17V
Board Features
The LME49600/LME49720 Stereo Headphone Amplifier
demonstration board has all of the necessary connections,
using RCA jacks, 1/8” stereo headphone jack and 0.100”
headers, to apply the power supply voltage and the audio in-
put signals. The amplified audio signal is available on both a
stereo headphone jack and auxiliary output connections.
Also present on the demonstration board is a potentiometer
to control the stereo output signal magnitude.
Schematic
Figure 2 shows the LME49600/LME49720 Stereo Head-
phone Amplifier Demonstration Board schematic. Refer to
Table 3 for a list of the connections and their functions.
Figure 2. The LME49600 Demonstration Board Schematic
Note: The LM4562, LME49720, or LME49860 can be used.
30047317
2
2024年4月27日发(作者：顿芷琪)
LME49600 Headphone Amplifier Evaluation Board User's Guide
LME49600 Headphone
Amplifier Evaluation Board
User's Guide
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
National Semiconductor
Application Note 1768
Kevin Hoskins
February 29, 2008
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
AN-1768
© 2008 National Semiconductor
A
N
-
1
7
6
8
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 amplifier’s feedback loop,
it increases output current, improves capacitive load drive,
and eliminates thermal feedback.
The LME49600 offers a pin-selectable bandwidth: a low cur-
rent, 110MHz bandwidth mode that consumes 8mA and a
wide 180MHz bandwidth mode that consumes 15mA. In both
modes the LME49600 has a nominal 2000V/μs slew rate.
Bandwidth is easily adjusted by either leaving the BW pin un-
connected, connecting a resistor between the BW pin and the
V
EE
pin or connecting the BW pin directly to the V
EE
pin.
The LME49600 is fully protected through internal current limit
and thermal shutdown.
Operating Conditions
■
Temperature Range
■
Amplifier Power
Supply Voltage
–40°C
≤
T
A
≤
85°C
2.5V
≤
V
S
±17V
Board Features
The LME49600/LME49720 Stereo Headphone Amplifier
demonstration board has all of the necessary connections,
using RCA jacks, 1/8” stereo headphone jack and 0.100”
headers, to apply the power supply voltage and the audio in-
put signals. The amplified audio signal is available on both a
stereo headphone jack and auxiliary output connections.
Also present on the demonstration board is a potentiometer
to control the stereo output signal magnitude.
Schematic
Figure 2 shows the LME49600/LME49720 Stereo Head-
phone Amplifier Demonstration Board schematic. Refer to
Table 3 for a list of the connections and their functions.
Figure 2. The LME49600 Demonstration Board Schematic
Note: The LM4562, LME49720, or LME49860 can be used.
30047317
2