NSC LM4881N, LM4881MM, LM4881MDC, LM4881M, LM4881MX Datasheet

LM4881

Dual 200 mW Headphone Amplifier with Shutdown Mode

General Description

The LM4881 is a dual audio power amplifier capable of deliv­ering 200 mW of continuous average power into an 8Ω load
with 0.1%(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 using surface mount packaging. Since
the LM4881 does not require bootstrap capacitors or snub­ber networks, it is optimally suited for low-power portable
systems.

The LM4881 features an externally controlled, low power
consumption shutdown mode which is virtually clickless and
popless, as well as an internal thermal shutdown protection
mechanism.

The unity-gain stable LM4881 can be configured by external
gain-setting resistors.

Key Specifications

n THD at 1 kHz at 125 mW

continuous average output
power into 8Ω 0.1%(max)

n THD at 1 kHz at 75 mW continuous

average output power into 32Ω 0.02%(typ)

n Output power at 10%THD+N

at 1 kHz into 8Ω 300 mW (typ)

n Shutdown Current 0.7 µA (typ)

Features

n MSOP surface mount packaging
n Unity-gain stable
n External gain configuration capability
n Thermal shutdown protection circuitry
n No bootstrap capacitors, or snubber circuits are

necessary

Applications

n Headphone Amplifier
n Personal Computers
n Microphone Preamplifier

Typical Application Connection Diagrams

Boomer®is a registered trademarkof National Semiconductor Corporation.

DS100005-1

*Refer to the Application Information Section for information concerning
proper selection of the input and output coupling capacitors.

FIGURE 1. Typical Audio Amplifier Application Circuit

MSOP Package

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SOP and DIP Package

DS100005-38

Top View

Order Number LM4881MM, LM4881M, or LM4881N

See NS Package Number MUA08A, M08A, or N08E

September 1997

LM4881 Dual 200 mW Headphone Amplifier with Shutdown Mode

© 1999 National Semiconductor Corporation DS100005 www.national.com

Absolute Maximum Ratings (Note 3)

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 4) Internally limited
ESD Susceptibility (Note 5) 3500V
ESD Susceptibility (Note 6) 250V
Junction Temperature 150˚C
Soldering Information (Note 1)

Small Outline Package

Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 220˚C

Thermal Resistance

θ

JC

(MSOP) 56˚C/W

θ

JA

(MSOP) 210˚C/W

θ

JC

(SOP) 35˚C/W

θ

JA

(SOP) 170˚C/W

θ

JC

(DIP) 37˚C/W

θ

JA

(DIP) 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

Note 1: See AN-450 “Surface Mounting and their Effects on Product Reli­ability” for other methods of soldering surface mount devices.

Electrical Characteristics (Notes 2, 3)

The following specifications apply for VDD= 5V unless otherwise specified. Limits apply for TA= 25C.

Symbol Parameter Conditions LM4881 Units (Limits)

Typ (Note 7) Limit (Note 8)

V

DD

Power Supply Voltage 2.7 V (min)

5.5 V (max)

I

DD

Quiescent Current VIN= 0V, IO= 0A 3.6 6.0 mA (max)

I

SD

Shutdown Current V

PIN1=VDD

0.7 5 µA (max)

V

OS

Offset Voltage VIN= 0V 5 50 mV (max)

P

O

Output Power THD = 0.1%(max);f=1kHz;

R

L

=8Ω 200 125 mW (min)

R

L

=16Ω 150 mW

R

L

=32Ω 85 mW
THD+N=10%;f=1kHz;
R

L

=8Ω 300 mW
R

L

=16Ω 200 mW
R

L

=32Ω 110 mW

THD+N Total Harmonic Distortion +

Noise

R

L

=16Ω,PO= 120 mWrms; 0.025

%

R

L

=32Ω,PO= 75 mWrms;
f=1kHz

0.02

%

PSRR C

B

= 1.0 µF, V

RIPPLE

= 200

mVrms, f = 120Hz

50 dB

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Electrical Characteristics (Notes 2, 3)

The following specifications apply for VDD= 3V unless otherwise specified. Limits apply for TA= 25C.

Symbol Parameter Conditions LM4881 Units (Limits)

Typ (Note 7) Limit (Note 8)

I

DD

Quiescent Current VIN= 0V, IO= 0A 1.1 mA

I

SD

Shutdown Current V

PIN1=VDD

0.7 µA

V

OS

Offset Voltage VIN=0V 5 mV

P

O

Output Power THD = 1%(max);

f = 1 kHz;
R

L

=8Ω 70 mW

R

L

=16Ω 65 mW

R

L

=32Ω 30 mW

THD+N=10%;
f = 1 kHz;

R

L

=8Ω 95 mW

R

L

=16Ω 65 mW

R

L

=32Ω 35 mW

THD+N Total Harmonic Distortion +

Noise

R

L

=16Ω,PO= 60 mWrms; 0.2

%

R

L

=32Ω,PO=

25 mWrms;f=1kHz

0.03

%

PSRR Power Supply Rejection Ratio C

B

= 1.0 µF, V

RIPPLE

=

200 mVrms, f = 100 Hz

50 dB

Note 2: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 3:

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 4: 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

)/θJA. For the LM4881, T

JMAX

= 150˚C, and the typical junction-to-ambient thermal resistance, when board

mounted, is 210˚C/W for the MSOP Package and 107˚C/W for package N08E.

Note 5: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 6: Machine Model, 220 pF–240 pF discharged through all pins.
Note 7: Typicals are measured at 25˚C and represent the parametric norm.
Note 8: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

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External Components Description (

Figure 1

)

Compo-

nents

Functional Description

1. R

i

Inverting input resistance which sets the closed-loop gain in conjuction with Rf. This resistor also
forms a high pass filter with C

i

at fc=1/(2πRiCi).

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 fc=1/(2πRiCi). Refer to the section, Proper Selection of External

Components, for and explanation of how to determine the value of C

i

.

3. R

f

Feedback resistance which sets closed-loop gain in conjuction with Ri.

4. C

S

Supply bypass capacitor which provides power supply filtering. Refer to the Application Information
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 section, Proper Selection of
External Components, for information concerning proper placement and selection of C

B

.

6. C

O

Output coupling capacitor which blocks the DC voltage at the amplifier’s output. Forms a high pass
filter with R

L

at fO= 1/(2πRLCO)

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 Frequency

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THD+N vs Frequency

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THD+N vs Frequency

DS100005-8

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