NSC LM4871M, LM4871N, LM4871MX Datasheet
LM4871
1.1W Audio Power Amplifier with Shutdown Mode
General Description
The LM4871 is a bridge-connected audio power amplifier capable of delivering typically 1.1W of continuous average
power to an 8Ω load with 0.5%(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 LM4871 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is optionally suited for low-power portable systems.
The LM4871 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism.
The unity-gain stable LM4871 can be configured by external
gain-setting resistors.
Key Specifications
n THD at 1 kHz at 1W continuous
average output power into 8Ω 0.5%(max)
n Output power at 10%THD+N
at 1 kHz into 8Ω
1.5W (typ)
n Shutdown Current 0.6 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 Desktop Computers
n Low Voltage Audio Systems
Typical Application Connection Diagram
Boomer®is a registered trademark of National Semiconductor Corporation.
DS100008-1
FIGURE 1. Typical Audio Amplifier Application Circuit
Small Outline and DIP Package
DS100008-2
Top View
Order Number LM4871M or LM4871N
See NS Package Number M08A or N08E
February 2000
LM4871 1.1W Audio Power Amplifier with Shutdown Mode
© 2000 National Semiconductor Corporation DS100008 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
Supply Temperature −65˚C to +150˚C
Input Voltage −0.3V to V
DD
to +0.3V
Power Dissipation (Note 3) Internally Limited
ESD Susceptibility (Note 4) 5000V
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.
θ
JC
(typ)— M08A 35˚C/W
θ
JA
(typ)— M08A 140˚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 2.0V ≤ V
DD
≤ 5.5V
Electrical Characteristics (Notes 1, 2)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for TA= 25˚C.
Symbol Parameter Conditions
LM4871
Units
(Limits)
Typical Limit
(Note 6) (Note 7)
V
DD
Supply Voltage 2.0 V (min)
5.5 V (max)
I
DD
Quiescent Power Supply Current VIN= 0V, Io= 0A 6.5 10.0 mA (max)
I
SD
Shutdown Current V
PIN1=VDD
0.6 2 µA (max)
V
OS
Output Offset Voltage VIN= 0V 5 50 mV (max)
P
o
Output Power THD = 0.5%(max);f=1kHz 1.10 1.0 W (min)
THD+N = 10%;f=1kHz 1.5 W
THD+N Total Harmonic Distortion+Noise P
o
= 1 Wrms; AVD=2;20Hz≤f
≤20 kHz
0.25
%
PSRR Power Supply Rejection Ratio V
DD
= 4.9V to 5.1V 65 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 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
JMAX–TA
)/θJAor the number given in Absolute Maximum Ratings, whichever is lower. For the LM4871, T
JMAX
= 150˚C. The
typical junction-to-ambient thermal resistance is 140˚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, 220 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).
LM4871
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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 fC= 1/(2π RiCi).
2. C
i
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
highpass filter with R
i
at fc= 1/(2π RiCi). 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 information concerning 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
.
Typical Performance Characteristics
THD+N vs Frequency
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THD+N vs Frequency
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THD+N vs Frequency
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THD+N vs Output Power
DS100008-6
THD+N vs Output Power
DS100008-7
THD+N vs Output Power
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Output Power vs
Supply Voltage
DS100008-9
Output Power vs
Supply Voltage
DS100008-10
Output Power vs
Supply Voltage
DS100008-11
LM4871
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