LM4882
250mW Audio Power Amplifier with Shutdown Mode
General Description
The LM4882 is a single-ended audio power amplifier ca-
pable of delivering 250 mW of continuous average power
into an 8
load with 1% (THD + N) from a 5V power supply.
Boomer
audio power amplifiers were designed specifically
to provide high quality output power with a minimal amount
of external components using surface mount packaging.
Since the LM4882 does not require bootstrap capacitors or
snubber networks, it is optimally suited for low-power por-
table systems.
The LM4882 features an externally controlled, low power
consumption shutdown mode which is virtually clickless and
popless, as well as an internal thermal shutdown protection
mechanism.
The unity-gain stable LM4882 can be configured by external
gain-setting resistors.
Key Specifications
n
THD + N at 1 kHz at 250 mW
continuous average output
power into 8
1.0% (max)
n
Output Power at 1% THD + N
at 1kHz into 4
380mW (typ)
n
THD + N at 1 kHz at 85 mW
continuous average output
power into 32
0.1% (typ)
n
Shutdown Current
0.7 A (typ)
Features
n
MSOP surface mount packaging
n
"Click and Pop" Suppression Circuitry
n
Supply voltages from 2.4V5.5V
n
Operating Temperature -40C to 85C
n
Unity-gain stable
n
External gain configuration capability
n
No bootstrap capacitors, or snubber circuits are
necessary
Applications
n
Personal Computers
n
Cellular Phones
n
General Purpose Audio
Typical Application
Connection Diagram
Boomer
is a registered trademark of National Semiconductor Corporation.
DS100030-1
*Refer to the Application Information Section for information concerning
proper selection of the input and output coupling capacitors.
FIGURE 1. Typical Audio Amplifier Application Circuit
MSOP and SOIC Package
DS100030-2
Top View
Order Number LM4882MM or LM4882M
See NS Package Number MUA08A or M08A
January 1998
LM4882
250mW
Audio
Power
Amplifier
with
Shutdown
Mode
1998 National Semiconductor Corporation
DS100030
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
6.0 V
Storage Temperature
-65C to +150C
Input Voltage
-0.3V to V
DD
+ 0.3V
Power Dissipation (Note 3)
Internally limited
ESD Susceptibility (Note 4)
2000V
PIn 5
1500V
Junction Temperature
150C
Soldering Information
Small Outline Package
Vapor Phase (60 seconds)
215C
Infrared (15 seconds)
220C
See AN-450
Surface Mounting and their Effects on
Product Reliability
for other methods of soldering surface
mount devices.
Thermal Resistance
JC
(MSOP)
56C/W
JA
(MSOP)
210C/W
JC
(SOP)
35C/W
JA
(SOP)
170C/W
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
85C
Supply Voltage
2.4V
V
DD
5.5V
Electrical Characteristics
(Notes 1, 2)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4882
Units
(Limits)
Typical
(Note 5)
Limit
(Note 6)
I
DD
Quiescent Current
V
IN
= 0V, I
O
= 0A
2
4.0
mA (max)
I
SD
Shutdown Current
V
pin1
= V
DD
0.5
5
A (max)
V
OS
Offset Voltage
V
IN
= 0V
5
50
mV (max)
P
O
Output Power
THD + N = 1% (max); f = 1 kHz;
R
L
= 4
380
mW
R
L
= 8
270
250
mW (min)
R
L
= 32
95
mW
THD + N = 10%; f = 1 kHz
R
L
= 4
480
mW
R
L
= 8
325
mW
R
L
= 32
125
mW
THD + N
Total Harmonic Distortion + Noise
R
L
= 8
, P
O
= 250 mWrms;
0.5
%
R
L
= 32
, P
O
= 85 mWrms;
0.1
%
f = 1 kHz
PSRR
Power Supply Rejection Ratio
V
pin3
= 2.5V, V
ripple
= 200 mVrms,
f = 120 Hz
50
dB
Electrical Characteristics
(Notes 1, 2)
The following specifications apply for V
DD
= 3V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4882
Units
(Limits)
Typical
(Note 5)
Limit
(Note 6)
I
DD
Quiescent Current
V
IN
= 0V, I
O
= 0A
1.2
mA
I
SD
Shutdown Current
V
pin1
= V
DD
0.3
A
V
OS
Offset Voltage
V
IN
= 0V
5
mV
P
O
Output Power
THD + N = 1% (max); f = 1 kHz
R
L
= 8
80
mW
R
L
= 32
30
mW
THD + N = 10%; f = 1 kHz
R
L
= 8
105
mW
R
L
= 32
40
mW
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2
Electrical Characteristics
(Notes 1, 2) (Continued)
The following specifications apply for V
DD
= 3V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4882
Units
(Limits)
Typical
(Note 5)
Limit
(Note 6)
THD + N
Total Harmonic Distortion + Noise
R
L
= 8
, P
O
= 70 mWrms;
0.25
%
R
L
= 32
, P
O
= 30 mWrms;
0.3
%
f = 1 kHz
PSRR
Power Supply Rejection Ratio
V
pin3
= 2.5V, V
ripple
= 200 mVrms,
f = 120 Hz
50
dB
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 func-
tional, but do not guarantee specific performance limits.
Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guar-
antee 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: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
JMAX
,
JA
, and the ambient temperature T
A
. The maximum
allowable power dissipation is P
DMAX
= (T
JMAX
- T
A
)/
JA
. For the LM4882, T
JMAX
= 150C, and the typical junction-to-ambient thermal resistance, when board
mounted, is 210C/W for the MUA08A Package and 170C/W for the M08A Package.
Note 4: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 5: Typicals are measured at 25C and represent the parametric norm.
Note 6: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
External Components Description
(Refer to
Figure 1)
Components
Functional Description
1. R
i
Inverting input resistance which sets the closed-loop gain in conjunction with R
f
. This resistor also forms a
high pass filter with C
i
at f
c
= 1 / (2
R
i
C
i
).
2. C
i
Input coupling capacitor which blocks the DC voltage at the amplifier's input terminals. Also creates a
highpass filter with R
i
at f
c
= 1 / (2
R
i
C
i
). Refer to the section, Proper Selection of External Components,
for an explanation of how to determine the values of C
i
.
3. R
f
Feedback resistance which sets closed-loop gain in conjunction with R
i
.
4. C
S
Supply bypass capacitor which provides power supply filtering. Refer to the Application Information section
for proper placement and selection of the supply bypass capacitor.
5. C
B
Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External
Components, for information concerning proper placement and selection of C
B
.
6. C
O
Output coupling capacitor which blocks the DC voltage at the amplifier's output. Forms a high pass filter wth
R
L
at f
O
= 1 / (2
R
L
C
O
).
Typical Performance Characteristics
THD+N vs Frequency
DS100030-26
THD+N vs Frequency
DS100030-9
THD+N vs Frequency
DS100030-10
3
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Typical Performance Characteristics
(Continued)
THD+N vs Frequency
DS100030-11
THD+N vs Frequency
DS100030-23
THD+N vs Frequency
DS100030-22
THD+N vs Frequency
DS100030-24
THD+N vs Frequency
DS100030-25
THD+N vs
Output Power
DS100030-29
THD+N vs
Output Power
DS100030-4
THD+N vs
Output Power
DS100030-8
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4
Typical Performance Characteristics
(Continued)
THD+N vs
Output Power
DS100030-30
THD+N vs
Output Power
DS100030-18
THD+N vs
Output Power
DS100030-19
THD+N vs
Output Power
DS100030-20
THD+N vs
Output Power
DS100030-21
Output Power vs
Supply Voltage
DS100030-12
Output Power vs
Supply Voltage
DS100030-13
Output Power vs
Supply Voltage
DS100030-14
5
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