LM4880
Dual 250 mW Audio Power Amplifier with Shutdown
Mode
General Description
The LM4880 is a dual audio power amplifier capable of deliv-
ering typically 250mW per channel of continuous average
power to an 8
load with 0.1% THD+N using 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 LM4880 does not require bootstrap capacitors or
snubber networks, it is optimally suited for low-power por-
table systems.
The LM4880 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism.
The unity-gain stable LM4880 can be configured by external
gain-setting resistors.
Key Specifications
n
THD+N at 1kHz at 200mW continuous average output
power into 8
: 0.1% (max)
n
THD+N at 1kHz at 85mW continuous average output
power into 32
: 0.1% (typ)
n
Output power at 10% THD+N at 1kHz into 8
:
325mW (typ)
n
Shutdown current: 0.7A (typ)
n
2.7V to 5.5V supply voltage range
Features
n
No bootstrap capacitors or snubber circuits are
necessary
n
Small Outline (SO) and DIP packaging
n
Unity-gain stable
n
External gain configuration capability
Applications
n
Headphone Amplifier
n
Personal Computers
n
CD-ROM Players
Typical Application
Boomer
is a registered trademark of National Semiconductor Corporation.
DS012343-1
*
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
August 2000
LM4880
Boomer
Audio
Power
Amplifier
Series
Dual
250
mW
Audio
Power
Amplifier
with
Shutdown
Mode
2000 National Semiconductor Corporation
DS012343
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Connection Diagram
Small Outline and
DIP Packages
DS012343-2
Top View
Order Number LM4880M or LM4880N
See NS Package Number M08A for SO
or NS Package Number N08E for DIP
LM4880
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2
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
6.0V
Storage Temperature
-65C to +150C
Input Voltage
-0.3V to V
DD
+ 0.3V
Power Dissipation (Note 3)
Internally limited
ESD Susceptibility (Note 4)
3500V
ESD Susceptibility (Note 5)
250V
Junction Temperature
150C
Soldering Information
Small Outline Package
Vapor Phase (60 sec.)
Infrared (15 sec.)
215C
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliability" for other methods of soldering surface
mount devices.
Thermal Resistance
JC
(DIP)
37C/W
JA
(DIP)
107C/W
JC
(SO)
35C/W
JA
(SO)
170C/W
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
+85C
Supply Voltage
2.7V
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
LM4880
Units
(Limits)
Typical
Limit
(Note 6)
(Note 7)
V
DD
Supply Voltage
2.7
V (min)
5.5
V (max)
I
DD
Quiescent Power Supply Current
V
IN
=0V, I
O
=0A
3.6
6.0
mA
(max)
I
SD
Shutdown Current
V
PIN5
=V
DD
0.7
5
A
(max)
V
OS
Output Offset Voltage
V
IN
=0V
5
50
mV
(max)
P
O
Output Power
THD=0.1% (max); f=1 kHz;
R
L
=8
250
200
mW
(min)
R
L
=32
85
mW
THD+N=10%; f=1 kHz
R
L
=8
325
mW
R
L
=32
110
mW
THD+N
Total Harmonic Distortion+Noise
R
L
=8
, P
O
=200 mW;
0.03
%
R
L
=32
, P
O
=75 mW;
0.02
%
f=1 kHz
PSRR
Power Supply Rejection Ratio
C
B
= 1.0 F,
V
RIPPLE
=200 mVrms, f = 100 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 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: 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
or the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4880, T
JMAX
= 150C,
and the typical junction-to-ambient thermal resistance is 170C/W for package M08A and 107C/W for package N08E.
Note 4: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 5: Machine model, 220 pF240 pF discharged through all pins.
Note 6: Typicals are measured at 25C and represent the parametric norm.
Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
LM4880
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3
Automatic Shutdown Circuit
Automatic Switching Circuit
External Components Description
(
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 high pass 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 value of C
i
.
3.
R
F
Feedback resistance which sets closed-loop gain in conjunction with R
i
.
DS012343-3
FIGURE 2. Automatic Shutdown Circuit
DS012343-4
FIGURE 3. Automatic Switching Circuit
LM4880
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4
External Components Description
(
Figure 1) (Continued)
Components
Functional Description
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 with R
L
at f
o
= 1/(2
R
L
C
o
).
Typical Performance Characteristics
THD + N vs Output Power
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THD + N vs Output Power
DS012343-6
THD + N vs Output Power
DS012343-7
THD + N vs Output Power
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THD + N vs Output Power
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THD + N vs Output Power
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THD + N vs Frequency
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THD + N vs Frequency
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THD + N vs Frequency
DS012343-13
LM4880
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