lm4884mhx National Semiconductor Corporation, lm4884mhx Datasheet

lm4884mhx

Manufacturer Part Number

lm4884mhx

Description

2.1w Differential Input, Btl Output Stereo Audio Amplifier With Rf Suppression And Shutdown

Manufacturer

National Semiconductor Corporation

Datasheet

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LM4884

2.1W Differential Input, BTL Output Stereo Audio

Amplifier with RF Suppression and Shutdown

General Description

The LM4884 features differential stereo inputs, BTL (bridge-

tied load) outputs, and four externally selectable fixed gains.

The LM4884 also features proprietary internal circuitry that

suppresses the coupling of RF signals into the chip. This is

important because certain types of RF signals (such as

GSM) can couple into audio amplifiers in such a way that

part of the signal is heard through the speaker. The RF

suppression circuitry in the LM4884 makes it well-suited for

notebook and portable applications in which strong RF sig-

nals generated by an antenna from a PC wireless card or a

cellular phone may couple audibly into the amplifier.

Operating on a single 5V supply, the LM4884 delivers 1.2W,

1.9W, or 2.1W (typ) of output power to an 8Ω, 4Ω, or 3Ω BTL

load (Note 1), respectively, with less than 1% THD+N. The

LM4884’s gain is selected using two digital inputs. The nomi-

nal gain values are 6dB, 10dB, 15.6dB, and 21.6dB.

Other features of the LM4884 are that it delivers high-quality

output power from a surface-mount package, requires few

external components, has an active-low micropower shut-

down mode input, and has thermal shutdown protection.

Key Specifications

Connection Diagram

Boomer

BTL output power

= 3Ω, V

= 4Ω, V

is a registered trademark of National Semiconductor Corporation.

= 5.0V, and THD+N = 1%

See NS Package Number MXA20A for Exposed-DAP TSSOP

DS201163

Order Number LM4884MH

2.1W (typ)

1.9W (typ)

Top View

Features

n Improved RF immunity, by up to 28dB over previous

n Fully differential input and output

n Internal gain set: 6dB, 10dB, 15.6dB, and 21.6dB

n Improved "click and pop" suppression

n Thermal shutdown protection circuit

n Ultra low current micropower shutdown mode

n 3.0V to 5.5V operation

n Available in space-saving exposed-DAP TSSOP

Applications

n Notebook computers

n PDAs

n Portable electronic devices

designs (such as the LM4874) in selected applications.

package

BTL output power

Micropower shutdown current

PSRR (

= 8Ω, V

20116302

1kHz, V

= 5.0V, and THD+N = 1%

= 5V, (Fig.1))

www.national.com

0.1µA (typ)

1.2W (typ)

62dB (typ)

April 2005

Related parts for lm4884mhx

lm4884mhx Summary of contents

Page 1

... BTL output power R = 4Ω 5.0V, and THD Connection Diagram See NS Package Number MXA20A for Exposed-DAP TSSOP Boomer ® registered trademark of National Semiconductor Corporation. © 2005 National Semiconductor Corporation j BTL output power R = 8Ω Micropower shutdown current j PSRR ( ...

Page 2

Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit www.national.com 2 20116301 ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Storage Temperature Input Voltage Power Dissipation (Note 4) ESD Susceptibility (Note 5) ESD Susceptibility (Note 6) Junction ...

Page 4

Electrical Characteristics for LM4884 Note 1: An LM4884MH that has been properly mounted to a circuit board with a copper heatsink area of at least 2in Note 2: All voltages are measured with respect to the GND pin unless other ...

Page 5

Typical Performance Characteristics THD vs Frequency 4Ω 1000mW OUT at (from top to bottom at 1kHz 21.6dB 15.6dB 10dB 6dB V ...

Page 6

Typical Performance Characteristics THD vs Output Power 3Ω (from top to bottom at 50mW 21.6dB 15.6dB 10dB 6dB V V THD ...

Page 7

Typical Performance Characteristics THD vs Output Power 4Ω 20kHz (from top to bottom at 200mW 21.6dB 15.6dB 10dB 6dB ...

Page 8

Typical Performance Characteristics Output Power vs Supply Voltage R = 4Ω 1kHz (from top to bottom at 4V): THD+N = 10%, THD PSRR vs Frequency 4Ω ...

Page 9

Typical Performance Characteristics THD vs Frequency 4Ω OUT at (from top to bottom at 1kHz 21.6dB 15.6dB 10dB 6dB V V THD ...

Page 10

Typical Performance Characteristics THD vs Output Power 4Ω (from top to bottom at 200mW 21.6dB 15.6dB 10dB 6dB V V ...

Page 11

Typical Performance Characteristics PSRR vs Frequency 4Ω SOURCE V = 200mV , at (from top to bottom at 1kHz): RIPPLE P 21.6dB 15.6dB 10dB, ...

Page 12

Typical Performance Characteristics Channel-to-Channel gain Mismatch vs Power Supply Voltage R = 8Ω 1kHz (from top to bottom at 4V 21.6dB 15.6dB 10dB 6dB V ...

Page 13

Typical Performance Characteristics Amplifier Power Dissipation vs Amplifier Load Dissipation 1kHz, at (from top to bottom at 0.3W 4Ω 8Ω, single channel driven and loaded L L Cross Talk ...

Page 14

Typical Performance Characteristics Cross Talk vs Frequency 8Ω Left channel driven, right channel measured Right channel driven, left channel measured Cross Talk vs Frequency V = 3V, R ...

Page 15

Typical Performance Characteristics A = Left channel driven, right channel measured Right channel driven, left channel measured Application Information OPTIMIZING RF IMMUNITY The internal circuitry of the LM4884 suppresses the amount of RF signal that is coupled into ...

Page 16

Application Information POWER DISSIPATION Power dissipation is a major concern when designing a successful bridged or single-ended amplifier. Equation (2) states the maximum power dissipation point for a single- ended amplifier operating at a given supply voltage and driving a ...

Page 17

Application Information Table 2. Logic Level Truth Table for Shutdown Operation SHUTDOWN OPERATIONAL MODE High Full Power, stereo BTL amplifiers Low Micro-power Shutdown SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4884’s performance requires properly se- lecting external components. Though the LM4884 ...

Page 18

Application Information Input Level: Input Impedance: Bandwidth: 100 Hz−20 kHz The design begins by specifying the minimum supply voltage necessary to obtain the desired output power. One way to find the minimum supply voltage is to use the Output Power ...

Page 19

Recommended Printed Circuit Board Layout FIGURE 2. Recommended MH PC Board Layout: FIGURE 3. Recommended MH PC Board Layout: (Continued) Component-Side Silkscreen Component-Side Layout 19 20116304 20116305 www.national.com ...

Page 20

Recommended Printed Circuit Board Layout www.national.com FIGURE 4. Recommended MH PC Board Layout: Upper Inner-Layer Layout FIGURE 5. Recommended MH PC Board Layout: Lower Inner-Layer Layout 20 (Continued) 20116306 20116307 ...

Page 21

Recommended Printed Circuit Board Layout FIGURE 6. Recommended MH PC Board Layout: (Continued) Bottom-Side Layout 21 20116308 www.national.com ...

Page 22

Physical Dimensions inches (millimeters) unless otherwise noted NS Package Number MXA20A for Exposed-DAP TSSOP National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time ...

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