LM2876
Overture
TM
Audio Power Amplifier Series
High-Performance 40W Audio Power Amplifier w/Mute
General Description
The LM2876 is a high-performance audio power amplifier
capable of delivering 40W of continuous average power to
an 8
load with 0.1% (THD + N) from 20 Hz20 kHz.
The performance of the LM2876, utilizing its Self Peak In-
stantaneous Temperature (Ke) (SPiKe
TM
) Protection Cir-
cuitry, puts it in a class above discrete and hybrid amplifiers
by providing an inherently, dynamically protected Safe Oper-
ating Area (SOA). SPiKe Protection means that these parts
are completely safeguarded at the output against overvolt-
age, undervoltage, overloads, including shorts to the sup-
plies, thermal runaway, and instantaneous temperature
peaks.
The LM2876 maintains an excellent Signal-to-Noise Ratio of
greater than 95 dB(min) with a typical low noise floor of
2.0 V. It exhibits extremely low (THD + N) values of 0.06%
at the rated output into the rated load over the audio spec-
trum, and provides excellent linearity with an IMD (SMPTE)
typical rating of 0.004%.
Features
n
40W continuous average output power into 8
n
75W instantaneous peak output power capability
n
Signal-to-Noise Ratio
95 dB(min)
n
An input mute function
n
Output protection from a short to ground or to the
supplies via internal current limiting circuitry
n
Output over-voltage protection against transients from
inductive loads
n
Supply under-voltage protection, not allowing internal
biasing to occur when |V
EE
| + |V
CC
|
12V, thus
eliminating turn-on and turn-off transients
n
11-lead TO-220 package
Applications
n
Component stereo
n
Compact stereo
n
Self-powered speakers
n
Surround-sound amplifiers
n
High-end stereo TVs
Typical Application
Overture
TM
and SPiKe
TM
Protection are trademarks of National Semiconductor Corporation.
DS011775-1
* Optional components dependent upon specific design requirements. Refer to the External Components Description section for a component functional
description.
FIGURE 1. Typical Audio Amplifier Application Circuit
August 1995
LM2876
Overture
Audio
Power
Amplifier
Series
High-Performance
40W
Audio
Power
Amplifier
w/Mute
1999 National Semiconductor Corporation
DS011775
www.national.com
Connection Diagram
DS011775-2
Connect Pin 5 to V
+
for Compatibility with LM3886.
*Preliminary: Call your local National sales rep. or distributor for availability.
Top View
Order Number LM2876T
or LM2876TF
See NS Package Number TA11B for
Staggered Lead Non-Isolated
Package or TF11B
*
for
Staggered Lead Isolated Package
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2
Absolute Maximum Ratings
(Notes 4, 5)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage |V
+
|+|V
-
| (No Signal)
72V
Supply Voltage |V
+
|+|V
-
| (Input Signal)
70V
Common Mode Input Voltage
(V
+
or V
-
) and
|V
+
| + |V
-
|
60V
Differential Input Voltage
60V
Output Current
Internally Limited
Power Dissipation (Note 6)
125W
ESD Susceptibility (Note 7)
3000V
Junction Temperature (Note 8)
150C
Soldering Information
T Package (10 seconds)
260C
Storage Temperature
-40C to +150C
Thermal Resistance
JC
1C/W
JA
43C/W
Operating Ratings
(Notes 4, 5)
Temperature Range
T
MIN
T
A
T
MAX
-20C
T
A
+85C
Supply Voltage |V
+
| + |V
-
|
20V to 60V
Note 1: Operation is guaranteed up to 60V, however, distortion may be intro-
duced from SPiKe Protection Circuitry if proper thermal considerations are
not taken into account. Refer to the Thermal Considerations section for
more information.
(See SPiKe Protection Response)
Electrical Characteristics
(Notes 4, 5)
The following specifications apply for V
+
= +30V, V
-
= -30V, I
MUTE
= -0.5 mA with R
L
= 8
unless otherwise specified. Limits
apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM2876
Units
(Limits)
Typical
Limit
(Note 9) (Note 10)
|V
+
| + |V
-
|
Power Supply Voltage (Note 13)
V
pin7
- V
-
9V
18
20
V (min)
60
V (max)
A
M
Mute Attenuation
Pin 8 Open or at 0V, Mute: On
Current out of Pin 8
>
0.5 mA,
115
80
dB (min)
Mute: Off
P
O
(Note 3)
Output Power (Continuous Average)
THD + N = 0.1% (max)
40
25
W (min)
f = 1 kHz; f = 20 kHz
Peak P
O
Instantaneous Peak Output Power
75
W
THD + N
Total Harmonic Distortion Plus Noise
25W, 20 Hz
f
20 kHz
0.06
%
A
V
= 26 dB
SR
(Note 3)
Slew Rate (Note 12)
V
IN
= 1.2 Vrms, f = 10 kHz,
9
5
V/s
(min)
Square-Wave, R
L
= 2 k
I
+
(Note 2)
Total Quiescent Power Supply Current
V
CM
= 0V, V
o
= 0V, I
o
= 0A
24
50
mA (max)
V
OS
(Note 2)
Input Offset Voltage
V
CM
= 0V, I
o
= 0 mA
1
10
mV (max)
I
B
Input Bias Current
V
CM
= 0V, I
o
= 0 mA
0.2
1
A (max)
I
OS
Input Offset Current
V
CM
= 0V, I
o
= 0 mA
0.01
0.2
A (max)
I
o
Output Current Limit
|V
+
| = |V
-
| = 10V, t
ON
= 10 ms, V
O
= 0V
4
3
A (min)
V
od
(Note 2)
Output Dropout Voltage (Note 14)
|V
+
V
O
|, V
+
= 20V, I
o
= +100 mA
1.5
4
V (max)
|V
O
V
-
|, V
-
= -20V, I
o
= -100 mA
2.5
4
V (max)
PSRR
(Note 2)
Power Supply Rejection Ratio
V
+
= 30V to 10V, V
-
= -30V,
125
85
dB (min)
V
CM
= 0V, I
o
= 0 mA
V
+
= 30V, V
-
= -30V to -10V,
110
85
dB (min)
V
CM
= 0V, I
o
= 0 mA
CMRR
(Note 2)
Common Mode Rejection Ratio
V
+
= 50V to 10V, V
-
= -10V to -50V,
110
75
dB (min)
V
CM
= 20V to -20V, I
o
= 0 mA
A
VOL
(Note 2)
Open Loop Voltage Gain
|V
+
| = |V
-
| = 30V, R
L
= 2 k
,
V
O
= 40V
115
80
dB (min)
GBWP
Gain-Bandwidth Product
|V
+
| = |V
-
| = 30V
8
2
MHz
(min)
f
O
= 100 kHz, V
IN
= 50 mVrms
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3
Electrical Characteristics
(Notes 4, 5) (Continued)
The following specifications apply for V
+
= +30V, V
-
= -30V, I
MUTE
= -0.5 mA with R
L
= 8
unless otherwise specified. Limits
apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM2876
Units
(Limits)
Typical
Limit
(Note 9) (Note 10)
eIN
(Note 3)
Input Noise
IHF -- A Weighting Filter
2.0
8
V (max)
R
IN
= 600
(Input Referred)
SNR
Signal-to-Noise Ratio
P
O
= 1W, A-Weighted,
98
dB
Measured at 1 kHz, R
S
= 25
P
O
= 25W, A-Weighted,
112
dB
Measured at 1 kHz, R
S
= 25
Ppk= 75W, A-Weighted,
117
dB
Measured at 1 kHz, R
S
= 25
IMD
Intermodulation Distortion Test
60 Hz, 7 kHz, 4:1 (SMPTE)
0.004
%
60 Hz, 7 kHz, 1:1 (SMPTE)
0.006
Note 2: DC Electrical Test; refer to Test Circuit #1.
Note 3: AC Electrical Test; refer to Test Circuit #2.
Note 4: All voltages are measured with respect to the GND pin (pin 7), unless otherwise specified.
Note 5: 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 6: For operating at case temperatures above 25C, the device must be derated based on a 150C maximum junction temperature and a thermal resistance of
JC
= 1.0 C/W (junction to case). Refer to the Thermal Resistance figure in the Application Information section under Thermal Considerations.
Note 7: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 8: The operating junction temperature maximum is 150C, however, the instantaneous Safe Operating Area temperature is 250C.
Note 9: Typicals are measured at 25C and represent the parametric norm.
Note 10: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 11: The LM2876T package TA11B is a non-isolated package, setting the tab of the device and the heat sink at V
-
potential when the LM2876 is directly
mounted to the heat sink using only thermal compound. If a mica washer is used in addition to thermal compound,
CS
(case to sink) is increased, but the heat sink
will be isolated from V
-
.
Note 12: The feedback compensation network limits the bandwidth of the closed-loop response and so the slew rate will be reduced due to the high frequency
roll-off. Without feedback compensation, the slew rate is typically larger.
Note 13: V
-
must have at least -9V at its pin with reference to ground in order for the under-voltage protection circuitry to be disabled.
Note 14: The output dropout voltage is the supply voltage minus the clipping voltage. Refer to the Clipping Voltage vs Supply Voltage graph in the Typical Perfor-
mance Characteristics section.
Test Circuit #1
(DC Electrical Test Circuit)
DS011775-3
www.national.com
4
Test Circuit #2
(AC Electrical Test Circuit)
Single Supply Application Circuit
DS011775-4
DS011775-5
*Optional components dependent upon specific design requirements. Refer to the External
Components Description section for a component functional description.
FIGURE 2. Typical Single Supply Audio Amplifier Application Circuit
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5
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