NSC LM4865MX, LM4865MMX, LM4865MM, LM4865M Datasheet

LM4865

750 mW Audio Power Amplifier with DC Volume Control
and Headphone Switch

General Description

The LM4865 is a mono bridged audio power amplifier with
DC volume control, capable of delivering 750 mW of continu­ous average power into an 8Ω load with less than 1%THD
from a 5V power supply. Switching between bridged speaker
mode and headphone (single ended) mode is accomplished
via a headphone sense pin. In addition, LM4865 is set into
low current consumption shutdown mode (0.7 µA typical) by
lowering the DC Vol/SD pin to below 0.3V.

Boomer audio power amplifiers are designed specifically to
provide high power audio output, with quality sound, from a
low supply voltage source while requiring the minimal
amount of external components.

Applications

n GSM phones and accessories, DECT, office phones

n Hand held radio
n Other portable audio devices

Key Specifications

n POat 1.0%THD+N into 8Ω (SOP): 750 mW (typ)
n P

O

at 10%THD+N into 8Ω (SOP): 1W (typ)

n Shutdown Current: 0.7 µA (typ)

Features

n DC volume control
n Headphone amplifier mode
n “Click and pop” suppression
n Shutdown control when volume control pin is low
n Thermal shutdown protection

Typical Application Connection Diagram

BOOMER™is a trademark ofNational Semiconductor Corporation.

DS101025-1

FIGURE 1. Typical Audio Amplifier

Application Circuit

MSOP, SOP Package

DS101025-2

Top View

Order Number LM4865M, LM4865MM

See NS Package Number M08A, MUA08A

December 1999

LM4865 750 mW Audio Power Amplifier with DC Volume Control and Headphone Switch

© 1999 National Semiconductor Corporation DS101025 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 (Note 3) Internally Limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Junction Temperature 150˚C

Soldering Information

Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C

Thermal Resistance

θ

JC

(SOP) 35˚C/W

θ

JA

(SOP) 150˚C/W

θ

JC

(MSOP) 56˚C/W

θ

JA

(MSOP) 190˚C/W

Operating Ratings

Temperature Range

T

MIN

≤ TA≤ T

MAX

−40˚C ≤ TA≤ +85˚C

Supply Voltage 2.7V ≤ V

DD

≤ 5.5V

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

Electrical Characteristics (Notes 1, 2)

he following specifications apply for V

DD

=

5V, unless otherwise specified. Limits apply for T

A

=

25˚C.

Symbol Parameter Conditions

LM4865

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

V

DD

Supply Voltage 2.7 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply
Current

VIN= 0V, IO= 0A, HP Sense = 0V 4 7 mA (max)
V

IN

= 0V, IO- 0A, HP Sense = 5V 3.5 6 mA (max)

I

SD

Shutdown Current V

PIN4

≤ 0.3V 0.7 µA

V

OS

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

P

O

Output Power THD = 1%(max), HP Sense<0.8V,f=1kHz,

R

L

=8Ω

750 500

mW

(max)

THD=10%(max), HP Sense

<

0.8V,

f = 1 kHz, R

L

=8Ω

1.0 W

THD+N=1%, HP Sense

>

4V,f=1kHz,

R

L

=32Ω

80 mW

THD=10%, HP Sense

>

4V,f=1kHz,

R

L

=32Ω

110 mW

THD+N Total Harmonic Distortion +

Noise

P

O

= 300 mWrms,f=20Hz–20kHz, RL=8Ω

0.6

%

PSSR Power Supply Rejection Ratio V

RIPPLE

= 200 mVrms, RL=8Ω,CB= 1.0 µF,

f=1kHz

50 dB

C

RANGE

Attenuator Range-Single Ended Gain with V

PIN4

≥ 4.0V, (80%of VDD) 20 18.8 dB (min)

Attenuation with V

PIN4

≤ 0.9V, (20%of VDD) −72 −70 dB (min)

V

IH

HP Sense High Input Voltage 4 V (max)

V

IL

HP Sense Low Input Voltage 0.8 V (min)

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

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

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 LM4865M, T

JMAX

=

150˚C.

Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 5: Machine Model, 220 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.

LM4865

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External Components Description

(

Figure 1

)

Components Functional Description

1. C

i

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

i

. The designer should note that10kOhm<(Ri)<110kOhm.Therefore fc=

1/(2πR

iCi

). Refer to the section, Proper Selection of External Components, for an explanation of how to

determine the value of C

i

.

2. C

S

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

3. 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

.

Typical Performance Characteristics

THD+N vs Frequency

DS101025-5

THD+N vs Frequency

DS101025-6

THD+N vs Output Power

DS101025-7

THD+N vs Output Power

DS101025-8

THD+N vs Output Power

DS101025-9

THD+N vs Output Power

DS101025-10

THD+N vs Output Power

DS101025-11

Power Dissipation vs Load
Resistance

DS101025-12

Power Dissipation vs Output Power

DS101025-13

LM4865

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