NSC LM4860MX, LM4860M Datasheet

LM4860

Series 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 1 to 10 without
the use of external compensation components.

Key Specifications

n THD+N at 1W continuous average

output power into 8Ω:1%(max)

n Instantaneous peak output power:

>

2W

n Shutdown current: 0.6 µA (typ)

Features

n No output coupling capacitors, bootstrap capacitors, or

snubber circuits are necessary

n Small Outline (SO) power 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

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

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FIGURE 1. Typical Audio Amplifier Application Circuit

Small Outline Package

DS011988-2

Top View

Order Number LM4860M

See NS Package Number M16A

August 1994

LM4860 1W Audio Power Amplifier with Shutdown Mode

© 1999 National Semiconductor Corporation DS011988 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
Storage Temperature −65˚C to +150˚C
Input Voltage −0.3V to V

DD

+ 0.3V
Power Dissipation Internally limited
ESD Susceptibility (Note 4) 3000V
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.

Operating Ratings

Temperature Range

T

MIN

≤ TA≤ T

MAX

−20˚C ≤ TA≤ +85˚C

Supply Voltage 2.7V ≤ V

DD

≤ 5.5V

Electrical Characteristics

(Notes 1, 2) The following specifications apply for V

DD

=

5V, R

L

=

8Ω unless otherwise specified. Limits apply for T

A

=

25˚C.

Symbol Parameter Conditions LM4860 Units

(Limits)

Typical Limit

(Note 6) (Note 7)

V

DD

Supply Voltage 2.7 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply Current V

O

=

0V, I

O

=

0A (Note 8) 7.0 15.0 mA (max)

I

SD

Shutdown Current V

pin2

=

V

DD

(Note 9) 0.6 µA

V

OS

Output Offset Voltage V

IN

=

0V 5.0 50.0 mV (max)

P

O

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

THD+N Total Harmonic Distortion + Noise P

O

=

1 Wrms; 20 Hz ≤ f ≤ 20 kHz 0.72

%

PSRR Power Supply Rejection Ratio V

DD

=

4.9V to 5.1V 65 dB

V

od

Output Dropout Voltage V

IN

=

0V to 5V, V

od

=

(V

o1−Vo2

) 0.6 1.0 V (max)

V

IH

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

V

IL

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

V

OH

HP-SENSE High Output Voltage I

O

=

500 µA 2.8 2.5 V (min)

V

OL

HP-SENSE Low Output Voltage I

O

=

−500 µA 0.2 0.8 V (max)

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 func-

tional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC 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 the Absolute Maximum Ratings, whichever is lower. For the LM4860, T

JMAX

=

+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.

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High Gain Application Circuit

Single Ended Application Circuit

External Components Description

(

Figures 1, 2

)

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 f

C

=

1/(2π R

iCi

).

2. C

i

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

i

at f

C

=

1/(2π R

iCi

).

3. R

f

Feedback resistance which sets closed-loop gain in conjunction 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 supply bypass capacitor.

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FIGURE 2. Stereo Amplifier with A

VD

=

20

DS011988-4

*

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

***

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

FIGURE 3. Single-Ended Amplifier with A

V

=

−1

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