National Semiconductor LM4880 Technical data

September 2004

LM4880 Dual 250 mW Audio Power Amplifier with Shutdown Mode

General Description

The LM4880 is a dual audio power amplifier capable of delivering typically 250mW per channel of continuous average power to an 8Ω load with 0.1% THD+N using 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 LM4880 does not require bootstrap capacitors or snubber networks, it is optimally suited for low-power portable systems.

The LM4880 features an externally controlled, low-power consumption shutdown mode, as well as an internal thermal shutdown protection mechanism.

The unity-gain stable LM4880 can be configured by external gain-setting resistors.

Key Specifications

n THD+N at 1kHz at 200mW continuous average output

power into 8Ω: 0.1% (max)

n THD+N at 1kHz at 85mW continuous average output

power into 32Ω: 0.1% (typ)

n Output power at 10% THD+N at 1kHz into 8Ω:

325mW (typ)

n Shutdown current: 0.7µA (typ) n 2.7V to 5.5V supply voltage range

Features

n No bootstrap capacitors or snubber circuits are

necessary

n Small Outline (SO) and DIP packaging n Unity-gain stable n External gain configuration capability

Applications

n Headphone Amplifier n Personal Computers n CD-ROM Players

LM4880 Boomer Audio Power Amplifier Series Dual 250 mW Audio Power Amplifier with

Shutdown Mode

Connection Diagram

Small Outline and

DIP Packages

01234302

Top View

Order Number LM4880M or LM4880N

See NS Package Number M08A for SO

or NS Package Number N08E for DIP

Boomer®is a registered trademark of National Semiconductor Corporation.

Typical Application

LM4880

*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

01234301

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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

0.3V

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

Thermal Resistance

(DIP) 37˚C/W

(DIP) 107˚C/W

(SO) 35˚C/W

(SO) 170˚C/W

Power Dissipation (Note 3) Internally limited

ESD Susceptibility (Note 4) 2000V

Operating Ratings

ESD Susceptibility (Note 5) 200V

Junction Temperature 150˚C

Soldering Information

Small Outline Package

Vapor Phase (60 sec.) Infrared (15 sec.)

215˚C 220˚C

Temperature Range

MIN≤TA≤TMAX

−40˚C≤TA≤+85˚C

Supply Voltage 2.7V≤V

≤5.5V

Electrical Characteristics (Notes 1, 2)

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

Symbol Parameter Conditions LM4880 Units

Typical Limit

(Note 6) (Note 7)

Supply Voltage 2.7 V (min)

5.5 V (max)

Quiescent Power Supply Current VIN=0V, IO=0A 3.6 6.0 mA

Shutdown Current V

PIN5=VDD

0.7 5 µA (max)

Output Offset Voltage VIN=0V 5 50 mV

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

=8Ω 250 200 mW

=32Ω 85 mW

THD+N=10%; f=1 kHz

=8Ω 325 mW

=32Ω 110 mW

THD+N Total Harmonic Distortion+Noise R

=8Ω,PO=200 mW; 0.03 %

=32Ω,PO=75 mW; 0.02 %

f=1 kHz

PSRR Power Supply Rejection Ratio C

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 may occur. Operating Ratings indicate conditions for which the device is functional, but

do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee

= 1.0 µF,

=200 mVrms, f = 100 Hz

RIPPLE

50 dB

(Limits)

(max)

(min)

Automatic Shutdown Circuit

LM4880

Automatic Switching Circuit

01234303

FIGURE 2. Automatic Shutdown Circuit

FIGURE 3. Automatic Switching Circuit

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External Components Description (Figure 1)

Components Functional Description

1. R

2. C

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

at fc= 1/(2πRiCi).

Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a high pass filter with R

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

External Components, for an explanation of how to determine the value of C

3. R

4. C

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

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

Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External Components, for information concerning proper placement and

at fo= 1/(2πRLCo).

6. C

selection of C

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

Typical Performance Characteristics

THD+NvsOutput Power THD+NvsOutput Power

LM4880

01234305 01234306

THD+NvsOutput Power THD+NvsOutput Power

01234307 01234308

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