LM4862
675 mW Audio Power Amplifier with Shutdown Mode
General Description
The LM4862 is a bridge-connected audio power amplifier ca-
pable of delivering typically 675mW of continuous average
power to an 8Ωload with 1% THD+N from a 5V power sup-
ply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4862 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is optimally suited for low-power portable sys-
tems.
The LM4862 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism.
The unity-gain stable LM4862 can be configured by external
gain-setting resistors.
Key Specifications
nTHD+N for 500mW continuous average
output power at 1kHz into 8Ω1% (max)
nOutput power at 10% THD+N at 1kHz into
8Ω825mW (typ)
nShutdown Current 0.7µA (typ)
Features
nNo output coupling capacitors, bootstrap capacitors or
snubber circuits are necessary
nSmall Outline or DIP packaging
nUnity-gain stable
nExternal gain configuration capability
nPin compatible with LM4861
Applications
nPortable computers
nCellular phones
nToys and games
Typical Application Connection Diagram
Boomer®is a registered trademark of National Semiconductor Corporation.
DS012342-1
*Refer to the Application Information section for information
concerning proper selection of the input coupling capacitor.
FIGURE 1. Typical Audio Amplifier Application Circuit
Small Outline and DIP Package
DS012342-2
Top View
Order Number LM4862M, LM4862N
See NS Package Number M08A or N08E
August 2000
LM4862 675 mW Audio Power Amplifier with Shutdown Mode
© 2000 National Semiconductor Corporation DS012342 www.national.com
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 −65˚C to +150˚C
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 150˚C
Soldering Information
Small Outline Package
Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C
See AN-450 “Surface Mounting and their Effects on
Product Reliability” for other methods of soldering surface
mount devices.
Thermal Resistance
θ
JC
(typ)—M08A 35˚C/W
θ
JA
(typ)—M08A 170˚C/W
θ
JC
(typ)—N08E 37˚C/W
θ
JA
(typ)—N08E 107˚C/W
Operating Ratings
Temperature Range
T
MIN
≤T
A
≤T
MAX
−40˚C ≤T
A
≤85˚C
Supply Voltage 2.7V ≤V
DD
≤5.5V
Electrical Characteristics(Note 1) (Note 2)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25˚C.
Symbol Parameter Conditions LM4862 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 (Note 8) 3.6 6.0 mA (max)
I
SD
Shutdown Current V
PIN1
=V
DD
0.7 5 µA (max)
V
OS
Output Offset Voltage V
IN
= 0V 5 50 mV (max)
P
O
Output Power THD = 1% (max); f = 1 kHz; R
L
=8Ω675 500 mW (min)
THD + N = 10%; f = 1 kHz; R
L
=8Ω825 mW
THD + N Total Harmonic Distortion +
Noise P
O
= 500 mWrms; R
L
=8Ω
A
VD
=2;20Hz≤f≤20 kHz 0.55 %
PSRR Power Supply Rejection Ratio V
DD
= 4.9V to 5.1V 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 andAC 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 TJMAX,θJA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX =(T
MAX −T
A
)/θJA. For the LM4862, TJMAX = 150˚C. The typical junction-to-ambient thermal resistance, when board mounted,
is 170˚C/W for package number M08A and is 107˚C/W for package number N08E.
Note 4: Human body model, 100 pF discharged through a 1.5 kΩresistor.
Note 5: Machine Model, 200 pF–240 pF discharged through all pins.
Note 6: Typicals are measured at 25˚C and represent the parametric norm.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.
LM4862
www.national.com 2
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/(2πR
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/(2πR
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 the closed-loop gain in conjunction with R
i
.
4. C
S
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
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 Proper Selection of External
Components section for proper placement and selection of the half-supply bypass capacitor.
DS012342-21
FIGURE 2. Automatic Switching Circuit
LM4862
www.national.com3
Typical Performance Characteristics
THD+N vs Frequency
DS012342-3
THD+N vs Frequency
DS012342-4
THD+N vs Frequency
DS012342-5
THD+N vs Output Power
DS012342-6
THD+N vs Output Power
DS012342-7
THD+N vs Output Power
DS012342-8
Output Power vs
Supply Voltage
DS012342-9
Output Power vs
Supply Voltage
DS012342-10
Output Power vs
Supply Voltage
DS012342-11
LM4862
www.national.com 4
Typical Performance Characteristics (Continued)
Output Power vs
Load Resistance
DS012342-12
Power Dissipation vs
Output Power
DS012342-13
Power Derating Curve
DS012342-14
Dropout Voltage vs
Power Supply
DS012342-15
Noise Floor
DS012342-16
Frequency Response vs
Input Capacitor Size
DS012342-17
Power Supply
Rejection Ratio
DS012342-18
Open Loop
Frequency Response
DS012342-19
Supply Current vs
Supply Voltage
DS012342-20
LM4862
www.national.com5
Application Information
BRIDGE CONFIGURATION EXPLANATION
As shown in
Figure 1
, the LM4862 has two operational am-
plifiers internally, allowing for a few different amplifier con-
figurations. The first amplifier’s gain is externally config-
urable, while the second amplifier is internally fixed in a
unity-gain, inverting configuration. The closed-loop gain of
the first amplifier is set by selecting the ratio of R
f
to R
i
while
the second amplifier’s gain is fixed by the two internal 10 kΩ
resistors.
Figure 1
shows that the output of amplifier one
serves as the input to amplifier two which results in both am-
plifiers producing signals identical in magnitude, but out of
phase 180˚. Consequently, the differential gain for the IC is
A
VD
=2
*
(R
f
/R
i
)
By driving the load differentially through outputs V
o1
and V
o2
,
an amplifier configuration commonly referred to as “bridged
mode” is established. Bridged mode operation is different
from the classical single-ended amplifier configuration where
one side of the load is connected to ground.
A bridge amplifier design has a few distinct advantages over
the single-ended configuration, as it provides differential
drive to the load, thus doubling output swing for a specified
supply voltage. Consequently, four times the output power is
possible as compared to a single-ended amplifier under the
same conditions. This increase in attainable output power
assumes that the amplifier is not current limited or clipped. In
order to choose an amplifier’s closed-loop gain without caus-
ing excessive clipping which will damage high frequency
transducers used in loudspeaker systems, please refer to
the Audio Power Amplifier Design section.
A bridge configuration, such as the one used in LM4862,
also creates a second advantage over single-ended amplifi-
ers. Since the differential outputs, V
o1
and V
o2
, are biased at
half-supply, no net DC voltage exists across the load. This
eliminates the need for an output coupling capacitor which is
required in a single supply, single-ended amplifier configura-
tion. Without an output coupling capacitor, the half-supply
bias across the load would result in both increased internal
lC power dissipation and also permanent loudspeaker dam-
age.
POWER DISSIPATION
Power dissipation is a major concern when designing a suc-
cessful amplifier, whether the amplifier is bridged or
single-ended. A direct consequence of the increased power
delivered to the load by a bridge amplifier is an increase in
internal power dissipation. Equation 1 states the maximum
power dissipation point for a bridge amplifier operating at a
given supply voltage and driving a specified output load.
P
DMAX
=4
*
(V
DD
)
2
/(2π
2
R
L
) (1)
Since the LM4862 has two operational amplifiers in one
package, the maximum internal power dissipation is 4 times
that of a single-ended amplifier. Even with this substantial in-
crease in power dissipation, the LM4862 does not require
heatsinking. From Equation 1, assuming a 5V power supply
and an 8Ωload, the maximum power dissipation point is
625 mW. The maximum power dissipation point obtained
from Equation 1 must not be greater than the power dissipa-
tion that results from Equation 2:
P
DMAX
=(T
JMAX
–T
A
)/θ
JA
(2)
For package M08A, θ
JA
= 170˚C/W and for package N08E,
θ
JA
= 107˚C/W. T
JMAX
= 150˚C for the LM4862. Depending
on the ambient temperature, T
A
, of the system surroundings,
Equation 2 can be used to find the maximum internal power
dissipation supported by the IC packaging. If the result of
Equation 1 is greater than that of equation 2, then either the
supply voltage must be decreased, the load impedance in-
creased, or the ambient temperature reduced. For the typical
application of a 5V power supply, with an 8Ωload, the maxi-
mum ambient temperature possible without violating the
maximum junction temperature is approximately 44˚C pro-
vided that device operation is around the maximum power
dissipation point. Power dissipation is a function of output
power and thus, if typical operation is not around the maxi-
mum power dissipation point, the ambient temperature can
be increased. Refer to the Typical Performance Character-
istics curves for power dissipation information for lower out-
put powers.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is criti-
cal for low noise performance and high power supply rejec-
tion. The capacitor location on both the bypass and power
supply pins should be as close to the device as possible. As
displayed in the Typical Performance Characteristics sec-
tion, the effect of a larger half supply bypass capacitor is im-
proved PSSR due to increased half-supply stability. Typical
applications employ a 5V regulator with 10 µF and a 0.1 µF
bypass capacitors which aid in supply stability, but do not
eliminate the need for bypassing the supply nodes of the
LM4862. The selection of bypass capacitors, especially C
B
,
is thus dependant upon desired PSSR requirements, click
and pop performance as explained in the section, Proper
Selection of External Components, system cost, and size
constraints.
SHUTDOWN FUNCTION
In order to reduce power consumption while not in use, the
LM4862 contains a shutdown pin to externally turn off the
amplifier’s bias circuitry. The shutdown feature turns the am-
plifier off when a logic high is placed on the shutdown pin.
The trigger point between a logic low and logic high level is
typically half supply. It is best to switch between ground and
supply to provide maximum device performance. By switch-
ing the shutdown pin to V
DD
, the LM4862 supply current
draw will be minimized in idle mode. While the device will be
disabled with shutdown pin voltages less than V
DD
, the idle
current may be greater than the typical value of 0.7 µA. In ei-
ther case, the shutdown pin should be tied to a definite volt-
age because leaving the pin floating may result in an un-
wanted shutdown condition.
In many applications, a microcontroller or microprocessor
output is used to control the shutdown circuitry which pro-
vides a quick, smooth transition into shutdown.Another solu-
tion is to use a single-pole, single-throw switch that when
closed, is connected to ground and enables the amplifier. If
the switch is open, then a soft pull-up resistor of 47 kΩwill
disable the LM4862. There are no soft pull-down resistors in-
side the LM4862, so a definite shutdown pin voltage must be
applied externally, or the internal logic gate will be left float-
ing which could disable the amplifier unexpectedly.
AUTOMATIC SWITCHING CIRCUIT
As shown in
Figure 2
, the LM4862 and the LM4880 can be
set up to automatically switch on and off depending on
whether headphones are plugged in. The LM4880 is used to
drive a stereo single ended load, while the LM4862 drives a
bridged internal speaker.
LM4862
www.national.com 6
Application Information (Continued)
The Automatic Switching Circuit is based upon a single
control pin common in many headphone jacks which forms a
normally closed switch with one of the output pins. The out-
put of this circuit (the voltage on pin 5 of the LM4880) has
two states based on the position of the switch. When the
switch inside the headphone jack is open, the LM4880 is en-
abled and the LM4862 is disabled since the NMOS inverter
is on. If a headphone jack is not present, it is assumed that
the internal speakers should be on and the external speak-
ers should be off. Thus the voltage on the LM4862 shutdown
pin is low and the voltage on the LM4880 shutdown pin is
high.
The operation of this circuit is rather simple. With the switch
closed, R
P
and R
O
form a resistor divider which produces a
gate voltage of less than 50 mV. The gate voltage keeps the
NMOS inverter off and R
SD
pulls the shutdown pin of the
LM4880 to the supply voltage. This shuts down the LM4880
and places the LM4862 in its normal mode of operation.
When the switch is open, the opposite condition is produced.
Resistor R
P
pulls the gate of the NMOS high which turns on
the inverter and produces a logic low signal on the shutdown
pin of the LM4880. This state enables the LM4880 and
places the LM4862 in shutdown mode.
Only one channel of this circuit is shown in
Figure 2
to keep
the drawing simple but a typical application would be a
LM4880 driving a stereo headphone jack and two LM4862’s
driving a pair of internal speakers. If a single internal speaker
is required, one LM4862 can be used as a summer to mix
the left and right inputs into a mono channel.
PROPER SELECTION OF EXTERNAL COMPONENTS
Proper selection of external components in applications us-
ing integrated power amplifiers is critical to optimize device
and system performance. While the LM4862 is tolerant of
external component combinations, consideration to compo-
nent values must be used to maximize overall system qual-
ity.
The LM4862 is unity-gain stable which gives a designer
maximum system flexibility. The LM4862 should be used in
low gain configurations to minimize THD+N values, and
maximize the signal to noise ratio. Low gain configurations
require large input signals to obtain a given output power. In-
put signals equal to or greater than 1 Vrms are available
from sources such as audio codecs. Please refer to the sec-
tion, Audio Power Amplifier Design , for a more complete
explanation of proper gain selection.
Besides gain, one of the major considerations is the
closed-loop bandwidth of the amplifier. To a large extent, the
band-width is dictated by the choice of external components
shown in
Figure 1
. The input coupling capacitor, C
i
, forms a
first order high pass filter which limits low frequency re-
sponse. This value should be chosen based on needed fre-
quency response for a few distinct reasons.
Selection of Input Capacitor Size
Large input capacitors are both expensive and space hungry
for portable designs. Clearly, a certain sized capacitor is
needed to couple in low frequencies without severe attenua-
tion. But in many cases the speakers used in portable sys-
tems, whether internal or external, have little ability to repro-
duce signals below 100–150 Hz. Thus using a large input
capacitor may not increase system performance.
In addition to system cost and size, click and pop perfor-
mance is effected by the size of the input coupling capacitor,
C
i
. A larger input coupling capacitor requires more charge to
reach its quiescent DC voltage (nominally
1
⁄
2
V
DD
). This
charge comes from the output via the feedback and is apt to
create pops upon device enable. Thus, by minimizing the ca-
pacitor size based on necessary low frequency response,
turn-on pops can be minimized.
Besides minimizing the input capacitor size, careful consid-
eration should be paid to the bypass capacitor value. Bypass
capacitor, C
B
, is the most critical component to minimize
turn-on pops since it determines how fast the LM4862 turns
on. The slower the LM4862’s outputs ramp to their quiescent
DC voltage (nominally
1
⁄
2
V
DD
), the smaller the turn-on pop.
Choosing C
B
equal to 1.0 µF along with a small value of C
i
(in the range of 0.1 µF to 0.39 µF), should produce a virtually
clickless and popless shutdown function. While the device
will function properly, (no oscillations or motorboating), with
C
B
equal to 0.1 µF, the device will be much more susceptible
to turn-on clicks and pops. Thus, a value of C
B
equal to
1.0 µF or larger is recommended in all but the most cost sen-
sitive designs.
LM4862
www.national.com7
Application Information (Continued)
AUDIO POWER AMPLIFIER DESIGN
Design a 500 mW/8ΩAudio Amplifier
Given:
Power Output 500 mWrms
Load Impedance 8Ω
Input Level 1 Vrms
Input Impedance 20 kΩ
Bandwidth 100 Hz–20 kHz ±0.25 dB
A designer must first determine the minimum supply rail to
obtain the specified output power. By extrapolating from the
Output Power vs Supply Voltage graphs in the Typical Per-
formance Characteristics section, the supply rail can be
easily found. A second way to determine the minimum sup-
ply rail is to calculate the required V
opeak
using equation 3
and add the dropout voltage. Using this method, the mini-
mum supply voltage would be (V
opeak
+(2
*
V
OD
)), where
V
OD
is extrapolated from the Dropout Voltage vs Supply Volt-
age curve in the Typical Performance Characteristics sec-
tion.
(3)
Using the Output Power vs Supply Voltage graph for an 8Ω
load, the minimum supply rail is 4.3V. But since 5V is a stan-
dard supply voltage in most applications, it is chosen for the
supply rail. Extra supply voltage creates headroom that al-
lows the LM4862 to reproduce peaks in excess of 500 mW
without clipping the signal. At this time, the designer must
make sure that the power supply choice along with the out-
put impedance does not violate the conditions explained in
the Power Dissipation section.
Once the power dissipation equations have been addressed,
the required differential gain can be determined from Equa-
tion 4.
(4)
R
f
/R
i
=A
VD
/2: (5)
From equation 4, the minimum A
VD
is 2; use A
VD
=2.
Since the desired input impedance was 20 kΩ, and with a
A
VD
of 2, a ratio of 1:1 of R
f
to R
i
results in an allocation of R
i
=R
f
=20kΩ. The final design step is to address the band-
width requirements which must be stated as a pair of −3 dB
frequency points. Five times away from a −3 dB point is
0.17 dB down from passband response which is better than
the required ±0.25 dB specified. This fact results in a low
and high frequency pole of 20 Hz and 100 kHz respectively.
As stated in the External Components section, R
i
in con-
junction with C
i
create a highpass filter.
C
i
≥1/(2π*20 kΩ*20 Hz) = 0.397 µF; use 0.39 µF.
The high frequency pole is determined by the product of the
desired high frequency pole, f
H
, and the differential gain,
A
VD
. With anA
VD
= 2 and f
H
= 100 kHz, the resulting GBWP
= 100 kHz which is much smaller than the LM4862 GBWP of
12.5 MHz. This figure displays that if a designer has a need
to design an amplifier with a higher differential gain, the
LM4862 can still be used without running into bandwidth
problems.
LM4862
www.national.com 8
Physical Dimensions inches (millimeters) unless otherwise noted
8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
Order Number LM4862M
NS Package Number M08A
8-Lead (0.300" Wide) Molded Dual-In-Line Package
Order Number LM4862N
NS Package Number N08E
LM4862
www.national.com9
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
National Semiconductor
Europe Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: ap.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
LM4862 675 mW Audio Power Amplifier with Shutdown Mode
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
National P/N LM4862 - 675 mW Audio Power Amplifier with Shutdown Mode
See Audio Products
Products > Audio > Boomer Audio Power Amplifiers <6V,<3W > LM4862
LM4862 Product Folder
675 mW Audio Power Amplifier with Shutdown Mode
Generic P/N 4862
General
Description Features Datasheet Package
& Models Samples
& Pricing
Parametric Table Parametric Table
Number of Channels 1
User Supply Voltage 3 V and 5 V
Power Supply Range +2.7 +5.5 V
Power at 4 Ohms, THD </=1% (Watt) .52
Power at 8 Ohms, THD </= 1% (Watt) .68
Power at 4 Ohms, THD </= 10% (Watt) .69
Power at 8 Ohms, THD </= 10% (Watt) .83
PSRR (dB) -
Typical THD Rating (%) .10
THD Measurement Conditions Po=0.4W @
Vs=5V, R=8
ohms
Datasheet
Title Size in
Kbytes Date View Online Download Receive via
Email
LM4862 675 mW Audio Power Amplifier with Shutdown
Mode 261
Kbytes
21-
Aug-
00 View Online Download Receive via
Email
LM4862 675 mW Audio Power Amplifier with Shutdown
Mode (JAPANESE)304
Kbytes
View Online
Download
Receive via
Email
If you have trouble printing or viewing PDF file(s), see Printing Problems.
Package Availability, Models, Samples & Pricing
Part
Number Package Status Models Samples &
Electronic
Orders
Budgetary
Pricing Std
Pack
Size
Package
Marking
Type Pins MSL SPICE IBIS Qty $US each
LM4862M SOIC
NARROW 8MSL Full
production N/A N/A
24 Hour
Samples
Buy Now
1K+ $0.5600 rail
of
95
[logo]¢2¢T
LM
4862M
LM4862MX SOIC
NARROW 8MSL Full
production N/A N/A
Buy Now
1K+ $0.5600 reel
of
2500
[logo]¢2¢T
LM
4862M
file:///H|/imaging/BITTING/cpl/20020808_1/08062002_10/NATL/08062002_HTML/LM4862.html (1 of 3) [09-Aug-2002 3:02:47 PM]
National P/N LM4862 - 675 mW Audio Power Amplifier with Shutdown Mode
LM4862N MDIP 8MSL Full
production N/A N/A
Samples
Buy Now
1K+ $0.5500 rail
of
40
[logo]¢U¢Z¢2¢T
LM4862N
LM4862 MDA Die Full
production N/A N/A
Samples
tray
of
N/A -
LM4862 MWA Wafer Full
production N/A N/A
wafer
jar
of
N/A
-
General Description
The LM4862 is a bridge-connected audio power amplifier capable of delivering typically 675mW of continuous
average power to an 8Ohm 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. Since the LM4862 does not require output coupling capacitors,
bootstrap capacitors, or snubber networks, it is optimally suited for low-power portable systems.
The LM4862 features an externally controlled, low-power consumption shutdown mode, as well as an internal
thermal shutdown protection mechanism.
The unity-gain stable LM4862 can be configured by external gain-setting resistors.
Features
● No output coupling capacitors, bootstrap capacitors or snubber circuits are necessary
● Small Outline or DIP packaging
● Unity-gain stable
● External gain configuration capability
● Pin compatible with LM4861
Key Specification
THD+N for 500mW continuous average output power at 1kHz into 8Ohm 1% (max)
Output power at 10% THD+N at 1kHz into 8Ohm 825mW (typ)
Shutdown Current 0.7µA (typ)
Applications
● Portable computers
● Cellular phones
● Toys and games
[Information as of 5-Aug-2002]
file:///H|/imaging/BITTING/cpl/20020808_1/08062002_10/NATL/08062002_HTML/LM4862.html (2 of 3) [09-Aug-2002 3:02:47 PM]
National P/N LM4862 - 675 mW Audio Power Amplifier with Shutdown Mode
Search Design Purchasing Quality Company Home
About Languages . Website Guide . About "Cookies" . National is QS 9000 Certified . Privacy/Security Statement .
Contact Us . Site Terms & Conditions of Use . Copyright 2002 © National Semiconductor Corporation . My Preferences .
Feedback
file:///H|/imaging/BITTING/cpl/20020808_1/08062002_10/NATL/08062002_HTML/LM4862.html (3 of 3) [09-Aug-2002 3:02:47 PM]
