NSC LM4841MTX, LM4841MHX, LM4841LQX, LM4841LQ, LM4841MT Datasheet

LM4841

Stereo 2W Amplifiers with DC Volume Control,
Transient Free Outputs, and Cap-less Headphone Drive

General Description

The LM4841 is a monolithic integrated circuit that provides
DC volume control and stereo bridged audio power amplifi­ers capable of producing 2W into 4Ω (Note 1) or 2.2W into
3Ω (Note 2) with less than 1.0% THD.

The LM4841 uses advanced, latest generation circuitry to
eliminate all traces of clicks and pops when the supply
voltages is first applied. The amplifier has a headphone­amplifier-select input pin that is used to switch the amplifiers
from bridge to single-ended mode for driving headphones. A
new circuit topology eliminates headphone output coupling
capacitors (patent pending).

Boomer

®

audio integrated circuits are designed specifically
to provide high quality audio while requiring a minimum
amount of external components. The LM4841 incorporates a
DC volume control, stereo bridged audio power amplifiers
and a selectable gain or bass boost, making it optimally
suited for multimedia monitors, portable radios, desktop, and
portable computer applications.

The LM4841 features an externally controlled, low-power
consumption shutdown mode (Shutdown Low), and both a
power amplifier and headphone mute for maximum system
flexibility and performance.

Note 1: When properly mounted to the circuit board, LM4841MH and
LM4841LQ will deliver 2W into 4Ω. The LM4841MT will deliver 1.1W into 8Ω.
See the Application Information section for LM4841MH usage information.

Note 2: An LM4841MH that has been properly mounted to the circuit board
and forced-air cooled will deliver 2.2W into 3Ω.

Key Specifications

n POat 1% THD+N
n into 3Ω (MH and LQ) 2.2W (typ)
n into 4Ω ( MH and LQ) 2.0W (typ)
n into 8Ω (MT, MH, and LQ) 1.1W (typ)
n Single-ended THD+N at 85mW into 32Ω 1.0%(typ)
n Shutdown current 0.7µA (typ)

Features

n Stereo headphone amplifier mode that eliminates the

Output Coupling Capacitors (patent pending)

n Acoustically Enhanced DC Volume Control Taper
n System Beep Detect
n Stereo switchable bridged/single-ended power amplifiers
n Selectable internal/external gain and bass boost
n Advanced “click and pop” suppression circuitry
n Thermal shutdown protection circuitry

Applications

n Portable and Desktop Computers
n Multimedia Monitors
n Portable Radios, PDAs, and Portable TVs

Connection Diagrams

TSSOP Package

20028002

Top View

Order Number LM4841MT or LM4841MH

See NS Package Number MTC28 for TSSOP and MXA28A for Exposed-DAP TSSOP

Boomer®is a registered trademark of National Semiconductor Corporation.

August 2002

LM4841 Stereo 2W Amplifiers with DC Volume Control,Transient Free Outputs, and Cap-less

Headphone Drive

© 2002 National Semiconductor Corporation DS200280 www.national.com

Connection Diagrams (Continued)

LLP Package

20028097

Top View

Order Number LM4841LQ

See NS Package Number LQA028AA for Exposed-DAP LLP

Block Diagram

20028001

FIGURE 1. LM4841 Block Diagram

LM4841

www.national.com 2

Absolute Maximum Ratings (Note 10)

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 11) Internally limited

ESD Susceptibility (Note 12)

All pins except Pin 28 2500V

Pin 28 6500V

ESD Susceptibility (Note 13) 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) — LQA028A 3˚C/W

θ

JA

(typ) — LQA028A 42˚C/W

θ

JC

(typ) — MTC28 20˚C/W

θ

JA

(typ) — MTC28 80˚C/W

θ

JC

(typ) — MXA28A 2˚C/W

θ

JA

(typ) — MXA28A (exposed

DAP) (Note 4)

41˚C/W

θ

JA

(typ) — MXA28A (exposed

DAP) (Note 3)

54˚C/W

θ

JA

(typ) — MXA28A (exposed

DAP) (Note 5)

59˚C/W

θ

JA

(typ) — MXA28A (exposed

DAP) (Note 6)

93˚C/W

Operating Ratings

Temperature Range

T

MIN

≤ TA≤T

MAX

−40˚C ≤TA ≤ 85˚C

Supply Voltage 2.7V≤ V

DD

≤ 5.5V

Electrical Characteristics for Entire IC (Notes 7, 10)

The following specifications apply for VDD= 5V unless otherwise noted. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4841

Units

(Limits)

Typical

(Note 14)

Limit

(Note 15)

V

DD

Supply Voltage 2.7 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply Current VIN= 0V, IO= 0A 15 30 mA (max)

I

SD

Shutdown Current V

shutdown

= GND 0.7 2.0 µA (max)

V

IH

Headphone Sense High Input Voltage 4 V (min)

V

IL

Headphone Sense Low Input Voltage 0.8 V (max)

TH

um

Un-Mute Threshold Voltage Gain 1st Stage = 1

V

shutdown

=V

DD

VINapplied to A or B input

22

10
40

mV

rms

mV

rms

Electrical Characteristics for Volume Attenuators (Notes 7, 10)

The following specifications apply for VDD= 5V. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4841

Units

(Limits)

Typical

(Note 14)

Limit

(Note 15)

C

RANGE

Attenuator Range Gain with V

DCVol

= 5V, No Load

±

0.75 dB (max)

Attenuation with V

DCVol

= 0V (BM &

SE)

-75 dB (min)

A

M

Mute Attenuation V

mute

= 5V, Bridged Mode (BM) -78 dB (min)

V

mute

= 5V, Single-Ended Mode (SE) -78 dB (min)

LM4841

www.national.com3

Electrical Characteristics for Single-Ended Mode Operation (Notes 7, 10)

The following specifications apply for VDD= 5V. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4841

Units

(Limits)

Typical

(Note 14)

Limit

(Note 15)

P

O

Output Power THD = 1.0%; f = 1kHz; RL=32Ω 85 mW

THD=10%;f=1kHz; R

L

=32Ω 95 mW

THD+N Total Harmonic Distortion+Noise V

OUT

=1V

RMS

, f=1kHz, RL= 10kΩ,

A

VD

=1

0.065 %

PSRR Power Supply Rejection Ratio C

B

= 1.0 µF, f =120 Hz,

V

RIPPLE

= 200 mVrms

58 dB

SNR Signal to Noise Ratio P

OUT

=75 mW, RL=32Ω, A-Wtd

Filter

102 dB

X

talk

Channel Separation f=1kHz, CB= 1.0 µF 65 dB

Electrical Characteristics for Bridged Mode Operation (Notes 7, 10)

The following specifications apply for VDD= 5V, unless otherwise noted. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4841

Units

(Limits)

Typical

(Note 14)

Limit

(Note 15)

V

OS

Output Offset Voltage VIN= 0V, No Load 5

±

50 mV (max)

P

O

Output Power THD+N=1.0%; f=1kHz; RL=3Ω

(Note 8)

2.2 W

THD+N=1.0%; f=1kHz; R

L

=4Ω

(Note 9)

2W

THD = 1% (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 mVrms; RL=8Ω

74 dB

SNR Signal to Noise Ratio V

DD

= 5V, P

OUT

= 1.1W, RL=8Ω,

A-Wtd Filter

93 dB

X

talk

Channel Separation f=1kHz, CB= 1.0 µF 70 dB

Note 3: The θJAgiven is for an MXA28A package whose exposed-DAP is soldered to an exposed 2in2piece of 1 ounce printed circuit board copper.

Note 4: The θ

JA

given is for an MXA28A package whose exposed-DAP is soldered to a 2in2piece of 1 ounce printed circuit board copper on a bottom side layer

through 21 8mil vias.

Note 5: The θ

JA

given is for an MXA28A package whose exposed-DAP is soldered to an exposed 1in2piece of 1 ounce printed circuit board copper.

Note 6: The θ

JA

given is for an MXA28A package whose exposed-DAP is not soldered to any copper.

Note 7: All voltages are measured with respect to the ground pins, unless otherwise specified. All specifications are tested using the typical application as shown
in Figure 1.

Note 8: When driving 3Ω loads from a 5V supply, LM4841MH and LM4841LQ must be mounted to the circuit board and forced-air cooled.

Note 9: When driving 4Ω loads from a 5V supply, the LM4841MH and LM4841LQ must be mounted to the circuit board.

Note 10: 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 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 11: 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 LM4841MT and LM4841LQ, T

JMAX

= 150˚C. See Power Dissipation for further information.

Note 12: Human body model, 100 pF discharged through a 1.5 kΩ resistor.

Note 13: Machine Model, 220 pF–240 pF discharged through all pins.

Note 14: Typicals are measured at 25˚C and represent the parametric norm.

Note 15: Limits are guaranteed to National’s AOQL ( Average Outgoing Quality Level). Datasheet min/max specification limits are guaranteed by design, test, or

statistical analysis.

LM4841

www.national.com 4

Typical Application

Truth Table for Logic Inputs

(Note 16)

Headphone

Sense

Gain Select Mode Mute Output Stage Set

To

Volume Control

X 0 0 0 Internal Gain On

X 0 0 0 Internal Gain On

X 1 0 0 External Gain On

X 1 0 0 External Gain On

On 0 1 0 Internal Gain On

Off 0 1 0 External Gain On

On 1 1 0 External Gain On

Off 1 1 0 Internal Gain On

X X X 1 X Muted

Note 16: If system beep is detected on the Beep In pin (pin 11), the system beep will be passed through the bridged amplifier regardless of the logic of the Mute
and HP sense pins.

20028003

FIGURE 2. Typical Application Circuit ( MT / MH Package Pinout )

LM4841

www.national.com5

Typical Performance Characteristics
MH/LQ Specific Characteristics

LM4841MH/LQ

THD+N vs Output Power

LM4841MH/LQ

THD+N vs Frequency

20028070

20028071

LM4841MH/LQ

THD+N vs Output Power

LM4841MH/LQ

THD+N vs Frequency

20028072

20028073

LM4841MH/LQ

Power Dissipation vs Output Power

LM4841MH/LQ (Note 17)

Power Derating Curve

20028065

20028064

Note 17: These curves show the thermal dissipation ability of the LM4841MH/LQ at different ambient temperatures given these conditions:

500LFPM + 2in

2

: The part is soldered to a 2in2, 1 oz. copper plane with 500 linear feet per minute of forced-air flow across it.

2in

2

on bottom: The part is soldered to a 2in2, 1oz. copper plane that is on the bottom side of the PC board through 21 8 mil vias.

2in

2

: The part is soldered to a 2in2, 1oz. copper plane.

1in

2

: The part is soldered to a 1in2, 1oz. copper plane.

Not Attached: The part is not soldered down and is not forced-air cooled.

LM4841

www.national.com 6

Non-MH/LQ Specific Characteristics

THD+N vs Frequency THD+N vs Frequency

20028057

20028058

THD+N vs Frequency THD+N vs Frequency

20028014

20028015

THD+N vs Frequency THD+N vs Frequency

20028016

20028017

LM4841

www.national.com7

Non-MH/LQ Specific Characteristics (Continued)

THD+N vs Frequency THD+N vs Frequency

20028018 20028019

THD+N vs Frequency THD+N vs Frequency

20028020

20028021

THD+N vs Frequency THD+N vs Output Power

20028022

20028024

LM4841

www.national.com 8

Non-MH/LQ Specific Characteristics (Continued)

THD+N vs Output Power THD+N vs Output Power

20028025

20028026

THD+N vs Output Power THD+N vs Output Power

20028027

20028028

THD+N vs Output Power THD+N vs Output Power

20028029

20028030

LM4841

www.national.com9

Non-MH/LQ Specific Characteristics (Continued)

THD+N vs Output Power THD+N vs Output Power

20028031

20028032

THD+N vs Output Power THD+N vs Output Power

20028033

20028034

THD+N vs Output Voltage

Docking Station Pins

THD+N vs Output Voltage

Docking Station Pins

20028059

20028060

LM4841

www.national.com 10