MAX9719 Maxim Integrated Products, MAX9719 Datasheet - Page 11

• Manufacturer Part Number: MAX9719
• Description: (MAX9718 / MAX9719) 1.4W Differential Audio Power Amplifiers
• Manufacturer: Maxim Integrated Products

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single-ended amplifiers. These capacitors can be
large, expensive, consume board space, and degrade
low-frequency performance.
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:
where T
ture, and θ
°C/W as specified in the Absolute Maximum Ratings
section. For example, θ
+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
maximum internal power dissipation for a given V
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
reduce V
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
Figure 1. Bridge-Tied Load Configuration
J(MAX)
CC
Power Dissipation and Heat Sinking
JA
, increase load impedance, decrease ambi-
P
DISSPKG MAX
is the reciprocal of the derating factor in
P
is +150°C, T
DISSPKG MAX
1.4W Differential Audio Power Amplifiers
______________________________________________________________________________________
+1
-1
(
(
JA
)
=
A
)
of the TQFN package is
T
=
J MAX
is the ambient tempera-
(
2
π
V
θ
2
CC
JA
R
)
L
−
2
T
A
V
2 x V
V
OUT(P-P)
OUT(P-P)
OUT(P-P)
CC
Low-Cost, Mono/Stereo,
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.
The MAX9718B, MAX9718C, MAX9718D, MAX9719B,
MAX9719C, and MAX9719D feature internally fixed
gains (see the Selector Guide). This simplifies design,
decreases required footprint size, and eliminates exter-
nal gain-setting resistors. Resistors R1 and R2 shown in
the Typical Operating Circuit are used to achieve each
fixed gain.
External feedback resistors set the gain of the
MAX9718A and MAX9719A. Resistors R
(Figure
where A
10kΩ and an R
R
digitally controlled potentiometer to alter the gain under
software control.
Figure
NONINVERTING
F
DIFFERENTIAL
DIFFERENTIAL
can be either fixed or variable, allowing the use of a
INVERTING
INPUT
INPUT (OPTIONAL)
2. Setting the MAX9718A/MAX9719A Gain
2) set the gain of the amplifier as follows:
V
(OPTIONAL)
is the desired voltage gain. Hence, an R
F
R
of 20kΩ yields a gain of 2V/V, or 6dB.
R
IN
IN
Adjustable Differential Gain
A
V
IN+
IN-
Fixed Differential Gain
=
GENERATOR
MAX9718A
MAX9719A
R
R
R
BIAS
F
IN
F
Gain-Setting Resistors
R
F
OUT+
OUT-
F
and R
IN
11
IN
of