NSC LM4834MSX, LM4834MS Datasheet

LM4834

1.75W Audio Power Amplifier with DC Volume Control
and Microphone Preamp

General Description

The LM4834 is a monolithic integrated circuit that provides
DC volume control, and a bridged audio power amplifier ca­pable of producing 1.75W into 4Ω with less than 1.0

%
(THD). In addition, the headphone/lineout amplifier is ca­pable of driving 70 mW into 32Ω with less than 0.1%(THD).
The LM4834 incorporates a volume control and an input mi­crophone preamp stage capable of drivinga1kΩload im-
pedance.

Boomer

®

audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components in surface mount packaging.
The LM4834 incorporates a DC volume control, a bridged
audio power amplifier and a microphone preamp stage,
making it optimally suited for multimedia monitors and desk­top computer applications.

The LM4834 features an externally controlled, low-power
consumption shutdown mode, and both a power amplifier
and headphone mute for maximum system flexibility and
performance.

Key Specifications

n THD at 1.1W continuous average

output power into 8Ω at 1 kHz 0.5%(max)

n Output Power into 4Ω at 1.0

%

THD+N

1.75W(typ)

n THD at 70mW continuous average

output power into 32Ω at 1 kHz

0.1%(typ)

n Shutdown Current 1.0µA(max)
n Supply Current 17.5mA(typ)

Features

n PC98 Compliant
n “Click and Pop” suppression circuitry
n Stereo line level outputs with mono input capability for

system beeps

n Microphone preamp with buffered power supply
n DC Volume Control Interface
n Thermal shutdown protection circuitry

Applications

n Multimedia Monitors
n Desktop and Portable Computers

Block Diagram Connection Diagram

Boomer®is a registered trademark of NationalSemiconductor Corporation.

DS100015-1

FIGURE 1. LM4834 Block Diagram

SSOP Package

DS100015-2

Top View

Order Number LM4834MS

See NS Package Number MSA028CB for SSOP

November 1997

LM4834 1.75W Audio Power Amplifier with DC Volume Control and Microphone Preamp

© 1997 National Semiconductor Corporation DS100015 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) 2000V
Pin 5 1500V
ESD Susceptibility (Note 5) 200V
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.

θ

JC

(typ)— MSA028CB 29˚C/W

θ

JA

(typ)— MSA028CB 95˚C/W

Operating Ratings

Temperature Range

T

MIN

≤ TA≤T

MAX

−40˚C ≤TA ≤ 85˚C

Supply Voltage 4.5 ≤ V

DD

≤ 5.5V

Electrical Characteristics for Entire IC

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

Symbol Parameter Conditions

LM4834

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

V

DD

Supply Voltage 4.5 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply Current VIN= 0V, IO= 0A 17.5 26 mA (max)

I

SD

Shutdown Current V

pin13=VDD

0.6 2.0 µA (max)

Electrical Characteristics for Volume Attenuators

(Notes 1, 2)
The following specifications apply for VDD= 5V. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4834

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

C

RANGE

Attenuator Range Gain with V

pin 22

= 5V 2.6 3.65 dB (max)

Attenuation with V

pin 22

= 0V -75 -88 dB (min)

A

M

Mute Attenuation V

pin 15

= 5V, Sum Out -92 -105 dB (max)

V

pin 15

= 5V, Line Out/Headphone

Amp

-92 -105 dB (max)

Electrical Characteristics for Microphone Preamp and Power Supply

(Notes 1, 2)
The following specifications apply forV

DD

= 5V unless otherwise noted. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4834

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

V

OS

Offset Voltage VIN= 0V 0.9 mV

SNR Signal to Noise Ratio V

DD

= 5V, RL=1k,f=1kHz, V

OUT

=

4.7V, A-Wtd Filter

123 dB

V

SWING

Output Voltage Swing f = 1 kHz, THD<1.0%,RL=1kΩ 4.72 V

E

NO

Input Referred Noise A-Weighted Filter 1.2 µV

PSRR Power Supply Rejection Ratio f = 120 Hz, V

RIPPLE

= 200 mVrms,

C

B

=1µF

28 dB

V

S

Mic Power Supply RL=1kΩ, Bias In = 2.5V 2.5 2.5 V (min)

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Electrical Characteristics for Line/Headphone Amplifier

(Notes 1, 2)
The following specifications apply for VDD= 5V. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4834

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

P

O

Output Power THD = 0.1%; f = 1kHz; RL=32Ω 70 mW

THD=10%;f=1kHz; R

L

=32Ω 95 mW

THD+N Total Harmonic Distortion+Noise V

OUT

=4V

P-P

,20Hz<f<20 kHz,

R

L

= 10kΩ,AVD=−1

0.05

%

PSRR Power Supply Rejection Ratio C

B

= 1.0 µF, f =120 Hz,

V

RIPPLE

= 200 mVrms

30 dB

SNR Signal to Noise Ratio V

DD

=5V, P

OUT

=75mW, RL=32Ω,

A-Wtd Filter

102 dB

Electrical Characteristics for Bridged Speaker Amplifer

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

Symbol Parameter Conditions

LM4834

Units

(Limits)

Typical

(Note 6)

Limit

(Note 7)

V

OS

Output Offset Voltage VIN= 0V 5 30 mV (max)

P

O

Output Power THD = 0.5%(max);f = 1 kHz;

R

L

=8Ω

1.1 1.0 W (min)

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

L

=8Ω 1.5 W

THD+N Total Harmonic Distortion+Noise P

O

= 1W, 20 Hz<f<20 kHz,

R

L

=8Ω,AVD=2

0.3

%

P

O

= 340 mW, RL=32Ω 1.0

%

PSRR Power Supply Rejection Ratio C

B

= 1.0 µF, f = 120 Hz,V

RIPPLE

=

200 mVmrs

58 dB

SNR Signal to Noise Ratio V

DD

= 5V, P

OUT

= 1.1W, RL=8Ω,

A-Wtd Filter

93 dB

Note 1: All voltages are measured with respect to the ground pins, unlessotherwise specified. All specifications are tested using the typical application as shown in

Figure 1

.

Note 2:

Absolute Maximum Ratings

indicate limits beyond which damage to the device may occur.

Operating Ratings

indicate conditionsfor which the device is func-

tional, 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 deviceis 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

)/θJA.For the LM4834MS, T

JMAX

= 150˚C, and the typical junction-to-ambient thermal resistance, when board

mounted, is 95˚C/W assuming the MSA028CB package.

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).

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Typical Application

Truth Table for Logic Inputs

Mode Mute HP Sense DC Vol. Control Line/HP Left Line/HP Right Speaker Out

0 0 0 Adjustable Fixed Level Fixed Level Vol. Changes
0 0 1 Adjustable Fixed Level Fixed Level Muted
0 1 X _ Fixed Level Fixed Level Muted
1 0 0 Adjustable Vol. Changes Vol. Changes Vol. Changes
1 0 1 Adjustable Vol. Changes Vol. Changes Muted
1 1 X _ Muted Muted Muted

External Components Description

Figure 2

Components. Functional Description

1. C

i

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

i

at fc= 1/(2πRiCi). 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

.

DS100015-3

FIGURE 2. Typical Application Circuit

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