LM4862
675 mW Audio Power Amplifier with Shutdown Mode

General Description

The LM4862 is a bridge-connected audio power amplifier ca-
pable of delivering typically 675 mW of continuous average
power to an 8

load with 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. Since the LM4862 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is optimally suited for low-power portable sys-
tems.

The LM4862 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism.

The unity-gain stable LM4862 can be configured by external
gain-setting resistors.

Key Specifications

THD at 500 mW continuous average

output power at 1 kHz into 8

1% (max)

Output power at 10% THD+N at

1 kHz into 8

825 mW (typ)

Shutdown Current

0.7 µA (typ)

Features

No output coupling capacitors, bootstrap capacitors or
snubber circuits are necessary

Small Outline or DIP packaging

Unity-gain stable

External gain configuration capability

Pin compatible with LM4861

Applications

Portable Computers

Cellular Phones

Toys and Games

Typical Application

Connection Diagram

Boomer

is a registered trademark of National Semiconductor Corporation.

DS012342-1

*Refer to the Application Information section for information
concerning proper selection of the input coupling capacitor.

FIGURE 1. Typical Audio Amplifier Application Circuit

Small Outline and DIP Package

DS012342-2

Top View

Order Number LM4862M, LM4862N

See NS Package Number M08A or N08E

May 1997

LM4862

675

Audio

Power

Amplifier

with

Shutdown

Mode

DS012342

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

+ 0.3V

Power Dissipation (Note 3)

Internally limited

ESD Susceptibility (Note 4)

3500V

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.

Thermal Resistance

(typ) -- M08A

35°C/W

(typ) -- M08A

170°C/W

(typ) -- N08E

37°C/W

(typ) -- N08E

107°C/W

Operating Ratings

Temperature Range

MIN

MAX

-40°C

85°C

Supply Voltage

2.7V

5.5V

Electrical Characteristics

(Note 1) (Note 2)

The following specifications apply for V

= 5V unless otherwise specified. Limits apply for T

= 25°C.

Symbol

Parameter

Conditions

LM4862

Units

(Limits)

Typical

Limit

(Note 6)

(Note 7)

Supply Voltage

2.7

V (min)

5.5

V (max)

Quiescent Power Supply Current

= 0V, I

= 0A (Note 8)

3.6

6.0

mA (max)

Shutdown Current

PIN1

= V

0.7

µA (max)

Output Offset Voltage

= 0V

mV (max)

Output Power

THD = 1% (max); f = 1 kHz; R

= 8

675

500

mW (min)

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

= 8

825

THD + N

Total Harmonic Distortion +
Noise

= 500 mWrms; R

= 8

= 2; 20 Hz

20 kHz

0.55

PSRR

Power Supply Rejection Ratio

= 4.9V to 5.1V

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 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 guar-
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

JMAX

, and the ambient temperature T

. The maximum

allowable power dissipation is P

DMAX

= (T

MAX

- T

. For the LM4862, T

JMAX

= 150°C. The typical junction-to-ambient thermal resistance, when board mounted,

is 170°C/W for package number M08A and is 107°C/W for package number N08E.

Note 4: Human body model, 100 pF discharged through a 1.5 k

resistor.

Note 5: Machine Model, 200 pF240 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.

www.national.com

Automatic Switching Circuit

External Components Description

(

Figure 1)

Components

Functional Description

Inverting input resistance which sets the closed-loop gain in conjunction with R

. This resistor also forms a

high pass filter with C

at f

= 1/(2

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

at f

= 1/(2

). Refer to the section, Proper Selection of External Components,

for an explanation of how to determine the value of C

Feedback resistance which sets the closed-loop gain in conjunction with R

Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
section for proper placement and selection of the supply bypass capacitor.

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

DS012342-21

FIGURE 2. Automatic Switching Circuit

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