MAX98307ETE+ Maxim Integrated, MAX98307ETE+ Datasheet - Page 15

• Manufacturer Part Number: MAX98307ETE+
• Description: Audio Amplifiers 3.3W Mono Class D Amplifier
• Manufacturer: Maxim Integrated

Specifications of MAX98307ETE+

• Rohs: yes
• Product: Class-D
• Output Type: Mono
• Output Power: 3.3 W
• Thd Plus Noise: 0.05 %
• Supply Current: 1.85 mA
• Maximum Power Dissipation: 1.667 W
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TQFN-16
• Common Mode Rejection Ratio (min): 65 dB

The speaker amplifier features Maxim’s comprehensive
click-and-pop suppression. During startup, the click-
and-pop suppression circuitry reduces any audible
transient sources internal to the device. When entering
shutdown, the differential speaker outputs quickly and
simultaneously ramp down to PGND.
The ICs automatically enter thermal shutdown when the
die temperature is greater than +160NC and reactivate at
less than +135NC. Additionally, if the outputs are shorted
to each other or either rail, the amplifier prevents cata-
strophic loss by disabling the outputs.
The ICs feature a low-power shutdown mode, drawing
less than 0.225FA (typ) supply current. Drive SHDN low
to put the IC into the shutdown state.
Traditional Class DG amplifiers require an output filter.
The filter adds cost and size, as well as decreases effi-
ciency and THD+N performance. The ICs’ active emis-
sions limiting and Class DG multilevel output modulation
allow for filterless operation while reducing external com-
ponent count, and thereby, cost.
Because the switching frequency of the ICs is well
beyond the bandwidth of most speakers, voice coil
movement due to the switching frequency is very small.
Use a speaker with a series inductance > 10FH. Typical
8I speakers exhibit series inductances in the 20FH to
100FH range.
The ICs feature a differential input configuration, making
the device compatible with many codecs and offering
improved noise immunity as compared to single-ended
input amplifiers. In devices such as mobile phones, noisy
digital signals can be picked up by an amplifier’s input
traces. A differential amplifier amplifies the difference
of the two inputs, while signals common to both inputs,
such as switching noise, are rejected. While both ICs
3.3W Mono Class DG Multilevel Audio Amplifier
Thermal and Short Circuit Protection
Applications Information
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Filterless Class DG Operation
Click-and-Pop Suppression
Differential Input Amplifier
Shutdown
feature differential amplifiers, their voltage gain is set in
differing manners.
The MAX98307 employs external feedback resistors as
shown in
set as:
where A
should be equal to R
In differential input configurations, the common-mode
rejection ratio (CMRR) is primarily limited by the external
resistor and capacitor matching. Ideally, to achieve the
highest possible CMRR, the following external compo-
nents should be selected where:
The gain of the MAX98308 is selectable by connecting
the gain-select bump GAIN as described in
Figure 4. Setting the Voltage Gain of the MAX98307
=
MAX98307/MAX98308
R
R
V
IN+
IN-
R
R
Figure
FB+
FB-
is the desired voltage gain in decibels. R
A
V
FB+
FB-
IN+
IN-
4. Voltage gain of the input amplifier is
20log
IN-
R
C
, and R
R
FB
IN
IN



R
R
+
+
+
and
FB
IN
=
=
FB+
C



R
R
( )
IN-
dB
FB-
IN-
should be equal to R
+
8.5dB
MAX98307
CLASS DG
OUTPUT
STAGE
Table
1.
FB- .
IN+