LM4682
10 Watt Stereo CLASS D Audio Power Amplifier with
Stereo Headphone Amplifier and DC Volume Control
General Description
The LM4682 is a fully integrated single supply, high effi-
ciency audio power amplifier solution. The LM4682 utilizes a
proprietary balanced pulse-width modulation technique that
lowers output noise and THD and improves PSRR when
compared to conventional pulse width modulators.
The LM4682 also features a stereo headphone amplifier that
delivers 60mW into a 32
headset with less than 0.5% THD.
The LM4682's DC volume control has a +30dB to 48dB
range when speakers are driven and a range of +13dB to
65dB when headphones are connected. All amplifiers are
protected by thermal shutdown. Additionally, all amplifiers
incorporate output current limiting function to protect their
outputs from short circuit.
The LM4682 features a low-power consumption shutdown
mode. And its efficiency reaches 85% for a 10W output
power with an 8
load. External heatsink is not required
when playing music. The IC features click and pop reduction
circuitry that minimizes audible popping during device
turn-on and turn-off. The LM4682 is available in a 48-lead
LLP package, ideal for portable and desktop computer ap-
plications.
Key Specifications
n
P
O
at THD+N = 10%, V
DD
= 14V
10W (typ)
n
THD+N at 1kHz at 6W into 8
(Power Amp) 0.2% (typ)
n
Efficiency at 7W into 8
84% (typ)
n
Total quiescent power supply current
52mA (typ)
n
Total shutdown power supply current
0.1mA (typ)
n
THD+N 1kHz, 20mW, 32
(Headphone)
0.02% (typ)
n
Single supply range
8.5V to 15V
Features
n
Pulse-width modulator.
n
DC Volume Control
n
Stereo headphone amplifier.
n
"Click and pop" suppression circuitry.
n
Micropower shutdown mode.
n
48 lead LLP package (No heatsink required).
Applications
n
Flat Panel Displays
n
Televisions
n
Multimedia Monitors
Boomer
is a registered trademark of National Semiconductor Corporation.
March 2006
LM4682
10
W
att
Stereo
CLASS
D
Audio
Power
Amplifier
with
Stereo
Headphone
Amplifier
and
DC
V
olume
Control
2006 National Semiconductor Corporation
DS201196
www.national.com
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
15.5V
Input Voltage
-0.3V to V
DD
+0.3V
Power Dissipation (Note 3)
Internally Limited
ESD Susceptibility (Note 4)
2000V
ESD Susceptibility (Note 5)
200V
Junction Temperature (Note 6)
150C
Storage Temperature
-65C
T
A
150C
Soldering Information
LLP Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliability" for other methods of soldering surface
mount devices.
Operating Ratings
(Notes 1, 2)
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
+85C
Supply Voltage
8.5V
V
DD
15V
Thermal Resistance (LLP Package)
JA
28C/W
JC
20C/W
Electrical Characteristics
(Notes 1, 2, 7)
The following specifications apply for V
DD
= 12V, VOLV
DD
= 5V, R
L
= 8
, LC filter values as shown in Figure 1, unless other-
wise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4682
Units
Typical
Max
Min
V
DD
Operating Supply Voltage Range
12
15
8.5
V
I
S
Quiescent Power Supply Current,
Class D Mode
V
IN
= 0V
RMS
, V
HPSEL
= 0V
52
70
mA
Quiescent Power Supply Current,
Headphone Mode
V
IN
= 0V
RMS
, V
HPSEL
= 12V
30
40
mA
I
SD
Quiescent Power Supply Current,
Shutdown Mode
SDB = 0V
0.1
mA
R
IN
Input Resistance in Both Modes
8
k
VOLV
DD
DC Reference Supply Voltage
5.5
3
V
V
IH
Minimum Logic High Input
Voltage
SDB, MUTEB pins
0.7xVOLV
DD
V
V
IL
Maximum Logic Low Input
Voltage
0.3xVOLV
DD
V
V
HPIH
HP Sense High Input Voltage
V
DD
-1
V
V
HPIL
HP Sense Low Input Voltage
V
DD
/2
V
Power Amplifiers
P
O
R
Output Power, Per Channel
THD+N
1%, f
IN
= 1kHz
6.0
5.5
W
P
D1
Power Dissipation
P
O
= 7W/Chan, f
IN
= 1kHz
2.6
W
E
FF1
Efficiency
P
O
= 7W/Chan, f
IN
= 1kHz
84.4
%
THD+N
Harmonic Distortion + Noise
P
O
= 6W/Chan, f
IN
= 1kHz
0.2
%
V
NOISE
Output Noise Voltage, RMS.
A-Weighted
R
SOURCE
= 50
, C
IN
= 1F,
BW = 8Hz to 22kHz
A-weighted, input referred
13
V
PSRR
Power Supply Rejection Ratio
V
RIPPLE
= 200mVpp, 1kHz,
V
IN
= 0, input referred
f = 50Hz
94
dB
f = 60Hz
94
f 100Hz
93
f = 120Hz
93
f = 1kHz
84
Headphone Amplifiers
LM4682
www.national.com
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