NSC LM4831VFX, LM4831VF Datasheet

LM4831
Multimedia Computer Audio Chip

General Description

The LM4831 is a monolithic integrated circuit that provides a
stereo three input mixer,twostereoinputanalogmultiplexer,
a stereo line out and a dual 1W bridged audio power ampli­fier. In addition, a low noise microphone preamp is included
on-chip.

The LM4831 is ideal for multimedia computers since it incor­porates an input mixer, analog multiplexer, and configurable
stereo audio power amplifier, as well as a microphone
preamp stage. This combination allows for all of the analog
audio processing to be enclosed in a 44-pin TQFP package.

The LM4831 features an externally controlled, low-power
consumption shutdown mode, as well as both headphone
and docking station modes.Totemporarilyoverridetheshut­down mode and allow audio signals to be amplified, the
LM4831 provides four “beep” pins.

Key Specifications

n THD+N at 1W into 8Ω 0.6%(typ)
n Microphone Input Referred Noise 10µV (typ)
n Supply Current - Bridged Mode 16mA (typ)
n Shutdown Current 2µA (typ)

Features

n Stereo 1W audio power amplifier
n “Click and pop” suppression circuitry
n Stereo three input mixer
n Shutdown mode
n Multiple operating modes— bridged, single-ended and

docking station modes

n Internal mux for switching in/out external filter
n Beep circuitry for “wake-up” while in shutdown
n 44 Pin TQFP Packaging

Applications

n Portable and Desktop Computers

Block Diagram Connection Diagram

Boomer®is a registered trademark of National Semiconductor Corporation.
TRI-STATE

®

is a registered trademark of National Semiconductor Corporation.

DS100057-1

FIGURE 1. LM4831 Block Diagram

DS100057-3

Top View

Order Number LM4831VF

See NS Package Number VEJ44A

November 1998

LM4831 Multimedia Computer Audio Chip

© 1998 National Semiconductor Corporation DS100057 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) 2500V
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.

Thermal Resistance

θ

JC

(typ) 15˚C/W

θ

JA

(typ) 62˚C/W

Operating Ratings

Temperature Range −40˚C to 85˚C
Supply Voltage 2.7 ≤ V

DD

≤ 5.5V

Electrical Characteristics

(Notes 1, 2) The following specifications apply for VDD= 5V, RL=8Ωandf=1kHz, unless otherwise specified. Distortion
measurements represent the full audio chain from Input A of each channel to their respective output. Limits apply for

T

A

= 25˚C.

Symbol Parameter Conditions

LM4831

Units

(Limits)

Typical

(Note

6)

Limit

(Note

7)

General Characteristics For Entire IC

V

DD

Supply Voltage 2.7 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply
Current

Bridged Mode, IO= 0 mA 16 50 mA (max)
Single-Ended Mode, I

O

= 0 mA 10.5 mA

Docking Station Mode, I

O

=0mA 7 mA

I

SD

Shutdown Current V

PIN-43

= 5V, V

PIN-41=VPIN-42

= 0V 2 50 µA (max)

V

DD/2

Half Supply Bypass Voltage VIN= 0V, V

Pin-43

= 0V 2.45 2.4 V (min)

2.6 V (max)

Power Amplifiers

P

O

Output Power - Bridged
Mode

RL=8Ω,THD = 1

%

1.1 1 W (min)

R

L

=4Ω,THD=1

%

1.5 W

Output Power ­Single-Ended Mode

R

L

=8Ω,THD=1

%

300 mW

R

L

=4Ω,THD=1

%

550 mW

THD Total Harmonic Distortion Bridged Mode, P

O

= 1W, RL=8Ω 0.5 2.0

%

(Max)

Single-Ended Mode, P

O

= 225mW,

R

L

=8Ω

0.15

%

V

OS

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

E

Noise

Input Referred Noise A-Weighted Filter, VIN= 0V,

R

L

=8Ω
Bridged Output 45 100 µV (max)
Single-Ended Output 35 100 µV (max)

PSRR Power Supply Rejection

Ratio

f = 1kHz, C

B

= 0.5µF, RL=8Ω
Bridged Output 47 dB
Single-Ended Output 45 dB

X

TALK

Channel to Channel
Crosstalk

f = 1kHz, PO= 1W, RL=8Ω
Right to Left −82 dB
Left to Right −73 dB

I

TS

TRI-STATE®Current-Single
Ended Mode

V

PIN-41

= 4.0V, L_PA+OUT =

R_PA+OUT = V

DD

or GND

80 100 µA (max)

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Electrical Characteristics (Continued)

(Notes 1, 2) The following specifications apply for VDD= 5V, RL=8Ωandf=1kHz, unless otherwise specified. Distortion
measurements represent the full audio chain from Input A of each channel to their respective output. Limits apply for

T

A

= 25˚C.

Symbol Parameter Conditions

LM4831

Units

(Limits)

Typical

(Note

6)

Limit

(Note

7)

Microphone Amplifier

THD Total Harmonic Distortion R

L

=10kΩ,VIN=1V

RMS

0.15

%

E

Noise

Input Referred Noise A-−weighted Filter 10 18 µV (max)

X

TALK

Crosstalk Amplifier Bridged Output, f = 1kHz,

P

O

= 1W, R

L-mic

= 20kΩ

95 dB

Other Audio Characteristics

THD Total Harmonic Distortion R

L

=20kΩ,VIN=1V

RMS

Line Out 0.15 0.5

%

(max)

Equalizer Out 0.01

%

E

Noise

Input Referred Noise A-weighted filter, Line Out 20 100 µV (max)

A

V

Channel Path Gain Line Out

±

0.1

±

0.7 dB (max)

Equalizer Out

±

0.1

±

0.6 dB (max)

MUX Out −0.25 −0.85,

+0.3

dB

E

T

Stereo Tracking Error Line Out

±

0.1

±

0.5 dB (max)

Digital Inputs and Outputs

V

IL

Input Low Voltage 1.0 V (max)

V

IH

Input High Voltage 4.0 V (min)

V

OL

Output Low Voltage 0.5 V (max)

V

OH

Output High Voltage 3.5 V (min)

Note 1: All voltages are measured with respect to the ground pins, 12, 17, 20, and 44, 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 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

)/θJA. For the LM4831, T

JMAX

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

mounted, is 62˚C/W assuming the VEF44A 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).

Digital Inputs Pin Truth Table

Pin Name LM4831 State

PWRDWN HPIN DSIN

0 0 0 Bridged Outputs Active

Equalizer In/Out Active
0 0 1 Line-Outs Active
0 1 X(Note 8) Single-Ended Outputs Active
1 X X Shutdown

Note 8: “X” means that the state of that pin does not matter in that particular input combination.

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Typical Application

DS100057-2

FIGURE 3. Typical Application Circuit

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