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PDF LM4681 Data sheet ( Hoja de datos )
| Número de pieza | LM4681 | |
| Descripción | Stereo CLASS D Audio Power Amplifier | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LM4681 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
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www.DataSheet4U.com
March 2006
LM4681
10 Watt Stereo CLASS D Audio Power Amplifier with
Stereo Headphone Amplifier and I2C/SPI Volume Control
General Description
The LM4681 is a fully integrated single supply, CLASS D
audio power amplifier solution. The LM4681 utilizes a pro-
prietary balanced pulse-width modulation technique that low-
ers output noise and THD and improves PSRR when com-
pared to conventional pulse width modulators.
The LM4681 also features a stereo headphone amplifier that
delivers 80mW into a 32Ω headset with less than 0.5% THD.
The LM4681’s I2C/SPI (selectable) 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. Addition-
ally, the high efficiency power amplifiers have output current
limit.
With a 8Ω load, the IC’s efficiency for a 6W power level is
85%. The IC features click and pop reduction circuitry that
minimizes audible popping during device turn-on and turn-
off. The LM4681 is available in a 48-lead LLP package, ideal
for portable and desktop computer applications.
Key Specifications
n PO at THD+N =10%, AV = 30dB, VDD = 14V 10W (typ)
n THD+N at 1kHz at 1W into 8Ω (Power Amp) 0.43% (typ)
n Efficiency at 7W into 8Ω
85% (min)
n Total quiescent power supply current
50mA (typ)
n THD+N 1kHz, 20mW, 32Ω (Headphone) 0.02% (typ)
n Single supply range
9.0V to 15.5V
Features
n Pulse-width modulator.
n I2C/SPI (selectable) 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
Block Diagram
Block Diagram for LM4681
BOOMER™ is a trademark of National Semiconductor Corporation.
© 2006 National Semiconductor Corporation DS201189
20118922
www.national.com
1 page  
Electrical Characteristics (Notes 1, 2, 7) (Continued)
The following specifications apply for VDD = 12V, I2CVDD = 5V, RL = 8Ω, LC filter values as shown in Figure 1, unless other-
wise specified. Limits apply for TA = 25˚C.
Symbol
Parameter
Conditions
LM4681
Typical
Limit
Units
VRIPPLE = 200mVP-P,
CBYPASS1 = 10µF,
input referred
PSRR
Power Supply Rejection Ratio
f = 50Hz
f = 60Hz
82
dB
84
f = 100Hz
92
f = 120Hz
95
f = 1kHz
95
Headphone Amplifiers
PO
Maximum Power Output Per
Channel
THD+N ≤ 1%, RL = 32Ω,
fIN = 1kHz
mW
94 70
(min)
THD+N
Distortion + Noise
PO = 20mW, RL = 32Ω,
fIN = 1kHz
0.02
%
RIN = 50Ω, CIN = 1µF,
VNOISE
Output Noise Voltage, RMS
BW = 20Hz to 20kHz, RL = 32Ω
22
µV
A-weighted, Input referred
PSRR
Power Supply Rejection Ratio
(Referred to Input)
200mV, 1kHz, VIN = 0, RL = 32Ω
77
dB
Electrical Characteristics for Volume Control (Notes 1, 2)
The following specifications apply for VDD = 12V. Limits apply for TA = 25˚C.
Symbol
Parameter
Conditions
CRANGE Gain Range
AM Mute Gain
Digital Code = Full Scale, No Load
Power Amplifier
Headphone Amplifier
Digital Code = +1LSB, No Load
Power Amplifier
Headphone Amplifier
Digital Code = 0, No Load
Power Amplifier
Headphone Amplifier
LM4681
Typical
(Note 8)
Limit
(Note 7)
Units
(Limits )
30 29 dB (min)
13 12 dB (min)
–48 –46 dB (min)
–65 –63 dB (min)
–74 dB (max)
–76 –74 dB (max)
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. “Operating Ratings” indicate conditions for which the device
is functional, but do not guarantee specific performance limits. “Electrical Characteristics” state DC and AC electrical specifications under particular test conditions
which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where
no limit is given, however, the typical value is a good indication of device performance.
Note 3: For operating at case temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a thermal resistance
of θJA = 80˚C/W (junction to ambient).
Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor.
Note 5: Machine Model 220pF − 240pF discharged through all pins.
Note 6: The operating junction temperature maximum is 150˚C.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: Typicals are measured at 25˚C and represent the parametric norm.
5 www.national.com
5 Page 
Typical Performance Characteristics (Continued)
Class D Amplifier Dissipation vs Load Dissipation
VDD = 12V, RL = 8Ω
Both channels driven and measured
Class D Amplifier Dissipation vs Load Dissipation
VDD = 15.5V, RL = 8Ω
Both channels driven and measured
20118960
Class D Amplifier Efficiency vs Total Output Power
VDD = 9V, RL = 8Ω
Both channels driven and measured
20118961
Class D Amplifier Efficiency vs Total Output Power
VDD = 12V, RL = 8Ω
Both channels driven and measured
20118962
Class D Amplifier Efficiency vs Total Output Power
VDD = 15.5V, RL = 8Ω
Both channels driven and measured
20118963
Output Power vs Load Resistance
VDD = 9V,
Upper curve = 10% THD+N, Lower curve = 1% THD+N
20118964
11
20118965
www.national.com
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet LM4681.PDF ] | |
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