National Semiconductor LM4860 Technical data

August 2000

LM4860 Series 1W Audio Power Amplifier with Shutdown Mode

LM4860 1W Audio Power Amplifier with Shutdown Mode

General Description

The LM4860 is a bridge-connected audio power amplifier capable of delivering 1W of continuous average power to an 8Ω load with less than 1% THD+N over the audio spectrum 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 LM4860 does not require output coupling capacitors, bootstrap capacitors or snubber networks, it is optimally suited for low-power portable systems.

The LM4860 features an externally controlled, low-power consumption shutdown mode, as well as an internal thermal shutdown protection mechanism. It also includes two headphone control inputs and a headphone sense output for external monitoring.

The unity-gain stable LM4860 can be configured by external gain setting resistors for differential gains of up to 10 without the use of external compensation components. Higher gains may be achieved with suitable compensation.

Key Specifications

n THD+N at 1W continuous average

output power into 8Ω: 1% (max)

n Instantaneous peak output power: n Shutdown current: 0.6µA (typ)

Features

n No output coupling capacitors, bootstrap capacitors, or

snubber circuits are necessary

n Small Outline (SO) packaging n Compatible with PC power supplies n Thermal shutdown protection circuitry n Unity-gain stable n External gain configuration capability n Two headphone control inputs and headphone sensing

output

Applications

n Personal computers n Portable consumer products n Cellular phones n Self-powered speakers n Toys and games

Typical Application Connection Diagram

Small Outline Package

Order Number LM4860M

See NS Package Number M16A

01198801

FIGURE 1. Typical Audio Amplifier Application Circuit

The Boomer®registered trademark is licensed to National Semiconductor for audio integrated circuits by Rockford Corporation. Patents pending.

Top View

01198802

Absolute Maximum Ratings (Note 2)

If Military/Aerospace specified devices are required,

LM4860

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 Internally limited

ESD Susceptibility (Note 4) 3000V

ESD Susceptibility (Note 5) 250V

Junction Temperature 150˚C

0.3V

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.

Operating Ratings

Temperature Range

≤ TA≤ T

MIN

MAX

Supply Voltage 2.7V ≤ VDD≤ 5.5V

−20˚C ≤ TA≤

Soldering Information

Electrical Characteristics

(Notes 1, 2) The following specifications apply for VDD= 5V, RL=8Ω unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4860 Units

Typical Limit

(Note 6) (Note 7)

THD+N Total Harmonic Distortion + Noise P

PSRR Power Supply Rejection Ratio V

Note 1: All voltages are measured with respect to the ground pins, 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

functional, 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 allowable power dissipation is P +150˚C, and the typical junction-to-ambient thermal resistance, when board mounted, is 100˚C/W.

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.

Note 9: Shutdown current has a wide distribution. For Power Management sensitive designs, contact your local National Semiconductor Sales Office.

Supply Voltage 2.7 V (min)

5.5 V (max)

Quiescent Power Supply Current VO= 0V, IO= 0A (Note 8) 7.0 15.0 mA (max)

Shutdown Current V

pin2=VDD

(Note 9) 0.6 µA

Output Offset Voltage VIN= 0V 5.0 50.0 mV (max)

Output Power THD+N = 1% (max);f=1kHz 1.15 1.0 W (min)

= 1 Wrms; 20 Hz ≤ f ≤ 20 kHz 0.72 %

= 4.9V to 5.1V 65 dB

Output Dropout Voltage VIN=0Vto5V,Vod=(Vo1−Vo2) 0.6 1.0 V (max)

HP-IN High Input Voltage HP-SENSE = 0V to 4V 2.5 V

HP-IN Low Input Voltage HP-SENSE = 4V to 0V 2.5 V

HP-SENSE High Output Voltage IO= 500 µA 2.8 2.5 V (min)

HP-SENSE Low Output Voltage IO= −500 µA 0.2 0.8 V (max)

, θJA, and the ambient temperature TA. The maximum

DMAX

=(T

JMAX−TA

)/θJAor the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4860, T

JMAX

+85˚C

(Limits)

JMAX

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High Gain Application Circuit

LM4860

01198803

FIGURE 2. Stereo Amplifier with AVD=20

Single Ended Application Circuit

*CSand CBsize depend on specific application requirements and constraints. Typical values of CSand CBare 0.1 µF.

**Pin 2, 6, or 7 should be connected to V

***These components create a “dummy” load for pin 8 for stability purposes.

to disable the amplifier or to GND to enable the amplifier. These pins should not be left floating.

01198804

FIGURE 3. Single-Ended Amplifier with AV=−1

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External Components Description

(Figures 1, 2)

LM4860

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 high pass filter with C

at fC= 1/(2π RiCi).

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

at fC= 1/(2π RiCi).

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 supply bypass capacitor.

5. C

Bypass pin capacitor which provides half supply filtering. Refer to Application Information section for proper placement and selection of bypass capacitor.

(Note 10) Used when a differential gain of over 10 is desired. Cfin conjunction with Rfcreates a low-pass filter

6. C

which bandwidth limits the amplifier and prevents high frequency oscillation bursts. f

Note 10: Optional component dependent upon specific design requirements. Refer to the Application Information section for more in formation.

Typical Performance Characteristics

THD+N vs Frequency THD+N vs Frequency

= 1/(2π RfCf)

01198809 01198810

THD+N vs Frequency THD+N vs Output Power

01198811 01198812

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