Power Dissipation and Heat Sinking

Under normal operating conditions, the MAX9718/

MAX9719 dissipate a significant amount of power. The

maximum power dissipation for each package is given

in the

Absolute Maximum Ratings section under

Continuous Power Dissipation or can be calculated by

the following equation:

ture, and

°C/W as specified in the

Absolute Maximum Ratings

section. For example,

+59.2°C/W.

The increase in power delivered by the BTL configura-

tion directly results in an increase in internal power dis-

sipation over the single-ended configuration. The

and load is given by the following equation:

If the internal power dissipation for a given application

exceeds the maximum allowed for a given package,

reduce power dissipation by increasing the ground

plane heat-sinking capability and the size of the traces

to the device (see the

Layout and Grounding section).

Other methods for reducing power dissipation are to

ent temperature, reduce gain, or reduce input signal.

Thermal-overload protection limits total power dissipa-

tion in the MAX9718/MAX9719. When the junction tem-

perature exceeds +160°C, the thermal protection

circuitry disables the amplifier output stage. The ampli-

fiers are enabled once the junction temperature cools

by 15°C. A pulsing output under continuous thermal

overload results as the device heats and cools.

For optimum power dissipation and heat sinking, con-

nect the exposed pad found on the µMAX, TDFN,

TQFN, and TSSOP packages to a large ground plane.

Fixed Differential Gain

The MAX9718B/E, MAX9718C/F, MAX9718D/G,

MAX9719B, MAX9719C, and MAX9719D feature inter-

nally fixed gains (see the

Selector Guide). This simpli-

fies design, decreases required footprint size, and

achieve each fixed gain.

Adjustable Differential Gain

Gain-Setting Resistors

External feedback resistors set the gain of the

(Figure 2) set the gain of the amplifier as follows:

10k

digitally controlled potentiometer to alter the gain under

software control.

A

R

R

V

F

IN

=

P

V

R

D MAX

CC

L

2

2

2

π

P

TT

D MAX

J MAX

A

JA

()

()

=

−

θ

Low-Cost, Mono/Stereo,

1.4W Differential Audio Power Amplifiers

______________________________________________________________________________________

11

+1

-1

Figure 1. Bridge-Tied Load Configuration

MAX9718A/H

MAX9719A

BIAS

GENERATOR

INVERTING

DIFFERENTIAL

INPUT

NONINVERTING

DIFFERENTIAL

INPUT (OPTIONAL)

(OPTIONAL)

IN+

IN-

OUT+

OUT-

Figure 2. Setting the MAX9718A/H/MAX9719A Gain