NSC LM4862N, LM4862MX, LM4862M Datasheet
LM4862
675 mW Audio Power Amplifier with Shutdown Mode
General Description
The LM4862 is a bridge-connected audio power amplifier capable of delivering typically 675 mW of continuous average
power to an 8Ω load with 1%(THD) 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.
Key Specifications
n THD at 500 mW continuous average
output power at 1 kHz into 8Ω 1%(max)
n Output power at 10%THD+N at
1 kHz into 8Ω 825 mW (typ)
n Shutdown Current 0.7 µA (typ)
Features
n No output coupling capacitors, bootstrap capacitors or
snubber circuits are necessary
n Small Outline or DIP packaging
n Unity-gain stable
n External gain configuration capability
n Pin compatible with LM4861
Applications
n Portable Computers
n Cellular Phones
n Toys and Games
Typical Application Connection Diagram
Boomer®is a registered trademark of National Semiconductor Corporation.
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*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
May 1997
LM4862 675 mW Audio Power Amplifier with Shutdown Mode
© 1999 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
≤ TA≤ T
MAX
−40˚C ≤ TA≤ 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; RL=8Ω 675 500 mW (min)
THD+N=10%;f=1 kHz; R
L
=8Ω 825 mW
THD + N Total Harmonic Distortion +
Noise
P
O
=
500 mWrms; R
L
=8Ω
A
VD
=
2; 20 Hz ≤ 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 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
, θJA, and the ambient temperature TA. The maximum
allowable power dissipation is P
DMAX
=
(T
MAX−TA
)/θJA. For the LM4862, T
JMAX
=
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 kΩ resistor.
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.
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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 Rf. This resistor also forms a
high pass filter with C
i
at f
c
=
1/(2πR
iCI
).
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
iCi
). 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 Ri.
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
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