TL H 7934
LM2878
Dual
5
Watt
Power
Audio
Amplifier
December 1994
LM2878 Dual 5 Watt Power Audio Amplifier
General Description
The LM2878 is a high voltage stereo power amplifier de-
signed to deliver 5W channel continuous into 8X loads The
amplifier is ideal for use with low regulation power supplies
due to the absolute maximum rating of 35V and its superior
power supply rejection The LM2878 is designed to operate
with a low number of external components and still provide
flexibility for use in stereo phonographs tape recorders and
AM-FM stereo receivers The flexibility of the LM2878 al-
lows it to be used as a power operational amplifier power
comparator or servo amplifier The LM2878 is internally
compensated for all gains greater than 10 and comes in an
11-lead single-in-line package (SIP) The package has been
redesigned resulting in the slightly degraded thermal char-
acteristics shown in the figure Device Dissipation vs Ambi-
ent Temperature
Features
Y
Wide operating range 6V 32V
Y
5W channel output
Y
60 dB ripple rejection output referred
Y
70 dB channel separation output referred
Y
Low crossover distortion
Y
AC short circuit protected
Y
Internal thermal shutdown
Applications
Y
Stereo phonographs
Y
AM-FM radio receivers
Y
Power op amp power comparator
Y
Servo amplifiers
Typical Applications
TL H 7934 1
of Bass Tone Control
Frequency Response
TL H 7934 2
FIGURE 1 Stereo Phonograph Amplifier with Bass Tone Control
C1995 National Semiconductor Corporation
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
35V
Input Voltage (Note 1)
g
0 7V
Operating Temperature (Note 2)
0 C to
a
70 C
Storage Temperature
b
65 C to
a
150 C
Junction Temperature
a
150 C
Lead Temperature (Soldering 10 sec )
a
260 C
Thermal Resistance
i
JC
10 C W
i
JA
55 C W
Electrical Characteristics
V
S
e
22V T
TAB
e
25 C R
L
e
8X A
V
e
50 (34 dB) unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
Total Supply Current
P
O
e
0W
10
50
mA
Operating Supply Voltage
6
32
V
Output Power Channel
f
e
1 kHz THD
e
10% T
TAB
e
25 C
5
5 5
W
f
e
1 kHz THD
e
10% V
S
e
12V
1 3
W
Distortion
f
e
1 kHz R
L
e
8X
0 20
%
P
O
e
50 mW
P
O
e
0 5W
0 15
%
P
O
e
2W
0 14
%
Output Swing
R
L
e
8X
V
S
b
6V
Vp-p
Channel Separation
C
BYPASS
e
50 mF C
IN
e
0 1 mF
f
e
1 kHz Output Referred
b
50
b
70
dB
V
O
e
4 Vrms
PSRR Power Supply
C
BYPASS
e
50 mF C
IN
e
0 1 mF
Rejection Ratio
f
e
120 Hz Output Referred
b
50
b
60
dB
V
ripple
e
1 Vrms
PSRR Negative Supply
Measured at DC Input Referred
b
60
dB
Common-Mode Range
Split Supplies
g
15V Pin 1
g
13 5
V
Tied to Pin 11
Input Offset Voltage
10
mV
Noise
Equivalent Input Noise
R
S
e
0 C
IN
e
0 1 mF
2 5
m
V
BW
e
20
b
20 kHz
CCIR
ARM
3 0
m
V
Output Noise Wideband
0 8
mV
R
S
e
0 C
IN
e
0 1 mF A
V
e
200
Open Loop Gain
R
S
e
51X f
e
1 kHz R
L
e
8X
70
dB
Input Bias Current
100
nA
Input Impedance
Open Loop
4
MX
DC Output Voltage
V
S
e
22V
10
11
12
V
Slew Rate
2
V mS
Power Bandwidth
3 dB Bandwidth at 2 5W
65
kHz
Current Limit
1 5
A
Note 1
g
0 7V applies to audio applications for extended range see Application Hints
Note 2
For operation at ambient temperature greater than 25 C the LM2878 must be derated based on a maximum 150 C junction temperature using a thermal
resistance which depends upon device mounting techniques
2
Typical Performance Characteristics
Ambient Temperature
Device Dissipation vs
Output) vs Frequency
Ratio (Referred to the
Power Supply Rejection
Output) vs Frequency
Ratio (Referred to the
Power Supply Rejection
Output) vs Supply Voltage
Ratio (Referred to the
Power Supply Rejection
Frequency
(Referred to the Output) vs
Channel Separation
vs Frequency
Total Harmonic Distortion
vs Frequency
Total Harmonic Distortion
vs Power Out
Total Harmonic Distortion
Frequency
Open Loop Gain vs
Supply Voltage
Power Output Channel vs
Power Out
Power Dissipation vs
TL H 7934 3
3
Equivalent Schematic Diagram
TLH7934
4
4
Connection Diagram
Single-In-Line Package
TL H 7934 5
Top View
Pin 6 must be connected to GND
Order Number LM2878P
See NS Package Number P11A
Application Hints
The LM2878 is an improved LM378 in typical audio applica-
tions In the LM2878 the internal voltage regulator for the
input stage is generated from the voltage on pin 1 Normally
the input common-mode range is within
g
0 7V of this pin 1
voltage Nevertheless the common-mode range can be in-
creased by externally forcing the voltage on pin 1 One way
to do this is to short pin 1 to the positive supply pin 11
The only special care required with the LM2878 is to limit
the maximum input differential voltage to
g
7V If this differ-
ential voltage is exceeded the input characteristics may
change
Figure 2 shows a power op amp application with A
V
e
1
The 100k and 10k resistors set a noise gain of 10 and are
dictated by amplifier stability The 10k resistor is boot-
strapped by the feedback so the input resistance is domi-
nated by the 1 MX resistor
TL H 7934 6
FIGURE 2 Operational Power Amplifier A
V
e
1
5
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