NSC LM4876M Datasheet
February 2000
LM4876
1.1W Audio Power Amplifier with Shutdown Logic Low
LM4876 1.1W Audio Power Amplifier with Shutdown Logic Low
General Description
The LM4876 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 LM4876 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is optionally suited for low-power portable systems.
The LM4876 features an externally controlled, low-power
consumption shutdown mode, which is achieved by driving
pin 1 with logic low. Additionally, the LM4876 features an internal thermal shutdown protection mechanism.
The LM4876 is unity-gain stable and 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
n Shutdown Current 0.01 µA (typ)
Features
n No output coupling capacitors, bootstrap capacitors, or
snubber circuits are necessary
n Small Outline packaging
n Unity-gain stable
n External gain configuration capability
n Pin compatible with LM4861 and LM4871
Applications
n Mobile Phones
n Portable Computers
n Desktop Computers
n Low Voltage Audio Systems
Typical Application Connection Diagram
1.5W (typ)
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer®is a registered trademark of National Semiconductor Corporation.
Small Outline Package
DS101299-2
Top View
Order Number LM4876M
See NS Package Number M08A
DS101299-1
© 2000 National Semiconductor Corporation DS101299 www.national.com
Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required,
LM4876
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
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
Electrical Characteristics (Notes 1, 2)
The following specifications apply for V
= 5V unless otherwise specified. Limits apply for TA= 25˚C.
DD
DD
+0.3V
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
(typ)— M08A 35˚C/W
JC
θ
(typ)— M08A 140˚C/W
JA
Operating Ratings
Temperature Range
T
≤ TA≤ T
MIN
MAX
Supply Voltage 2.0V ≤ V
−40˚C ≤ TA≤ 85˚C
DD
≤ 5.5V
Symbol Parameter Conditions
V
DD
Supply Voltage 2.0 V (min)
LM4876
Typical Limit
(Note 6) (Note 7)
Units
(Limits)
5.5 V (max)
I
DD
I
SD
V
OS
P
o
Quiescent Power Supply Current VIN= 0V, Io= 0A 6.5 10.0 mA (max)
Shutdown Current V
= 0V 0.01 2 µA (max)
PIN1
Output Offset Voltage VIN= 0V 5 50 mV (max)
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
= 1 Wrms; AVD=2;20Hz≤f
o
0.25
≤20 kHz
PSRR Power Supply Rejection Ratio V
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2:
Absolute Maximum Ratings
tional, but do not guarantee specific performance limits.
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 T
allowable power dissipation is P
typical junction-to-ambient thermal resistance is 140˚C/W for package number M08A.
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).
indicate limits beyond which damage to the device may occur.
=(T
DMAX
JMAX–TA
Electrical Characteristics
)/θJAor the number given in Absolute Maximum Ratings, whichever is lower. For the LM4876, T
= 4.9V to 5.1V 65 dB
DD
state DC andAC electrical specifications under particular test conditions which guar-
Operating Ratings
JMAX
indicate conditions for which the device is func-
, θJA, and the ambient temperature TA. The maximum
JMAX
= 150˚C. The
%
Electrical Characteristics VDD= 5/3.3/2.6V
Symbol Parameter Conditions
V
IH
V
IL
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Shutdown Input Voltage High 1.2 V(min)
Shutdown Input Voltage Low 0.4 V(max)
LM4876
Typical Limit
(Note 6) (Note 7)
Units
(Limits)
LM4876
External Components Description (
Figure 1
)
Components Functional Description
1. R
2. C
3. R
4. C
Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a
i
high pass filter with C
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
i
highpass filter with R
for an explanation of how to determine the value of C
Feedback resistance which sets the closed-loop gain in conjunction with Ri.
f
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
S
at fC= 1/(2π RiCi).
i
at fc= 1/(2π RiCi). Refer to the section, Proper Selection of External Components,
i
.
i
section for information concerning proper placement and selection of the supply bypass capacitor.
5. C
Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External
B
Components, for information concerning proper placement and selection of C
Typical Performance Characteristics
THD+N vs Frequency
THD+N vs Frequency
.
B
THD+N vs Frequency
THD+N vs Output Power
Output Power vs
Supply Voltage
DS101299-3
DS101299-6
THD+N vs Output Power
Output Power vs
Supply Voltage
DS101299-4
DS101299-7
DS101299-5
THD+N vs Output Power
DS101299-8
Output Power vs
Supply Voltage
DS101299-9
DS101299-10
DS101299-11
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