MAX98307ETE+ Maxim Integrated, MAX98307ETE+ Datasheet - Page 16

• 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

Table 1. MAX98308 Gain Configuration
Note: For both ICs, the Class DG output stage has a fixed gain of 8.5dB. Any gain or attenuation set by the external input stage
resistors adds to or subtracts from this fixed gain.
PVDD powers the speaker amplifier and has a range
of 2.6V to 5.25V. Bypass PVDD with 0.1FF and 10FF
capacitors in parallel to PGND. Apply additional bulk
capacitance at the device if long input traces between
PVDD and the supply are used.
The AC-coupling capacitors (C
(R
an input signal. See the
Circuit
prevents any DC components from the input signal
source appearing at the amplifier outputs. The -3dB point
of the highpass filter, assuming zero source impedance
due to the input signal source, is given by:
Choose C
quency of interest. Setting f
amplifier’s low-frequency response. Use capacitors with
adequately low voltage coefficient (X5R or X7R recom-
mended) for best low frequency THD+N performance.
Use capacitors with an equivalent series resistance
(ESR) less than 50mI for optimum performance. Low-
ESR ceramic capacitors minimize the output resistance
of the charge pump. For best performance over the
extended temperature range, select capacitors with an
X7R dielectric and a rated voltage of at least 6.3V.
IN
) form highpass filters that remove any DC bias from
and
3.3W Mono Class DG Multilevel Audio Amplifier
IN
MAX98308 Typical Application
100kI to V
100kI to PGND
Short to V
Short to PGND
so that f
Unconnected
f
GAIN
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−
3dB
Charge-Pump Capacitor Selection
PVDD
-3dB
PVDD
=
2
MAX98307 Typical Application
π ×
Power-Supply Input (PVDD)
is well below the lowest fre-
Input Coupling Capacitors
Component Selection
R
-3dB
IN
1
IN
×
) and input resistors
C
too high affects the
IN
Circuit. C
PREAMPLIFIER GAIN (dB)
IN
12
0
3
6
9
The value of the charge-pump flying capacitor affects
the load regulation and output resistance of the charge
pump. A charge-pump flying capacitor value that is too
small (less than 1FF) degrades the amplifier’s ability to
provide sufficient current drive. Increasing the value of
this flying capacitor and decreasing the ESR improves
load regulation and reduces the charge-pump output
impedance, which improves the output power and effi-
ciency of the amplifier. A 4.7FF or greater value, low-ESR
capacitor is recommended.
The charge-pump hold capacitor value and ESR directly
affect the ripple at the charge-pump rail, PVSS. Increasing
the charge-pump hold capacitor value reduces output
ripple. Likewise, decreasing the ESR of this capacitor
reduces both ripple and output resistance. A 10FF or
greater value, low-ESR capacitor is recommended.
Proper layout and grounding are essential for optimum
performance. Good grounding improves audio perfor-
mance and prevents switching noise from coupling into
the audio signal.
Use wide, low-resistance output traces. As load imped-
ance decreases, the current drawn from the device
increases. At higher current, the resistance of the output
traces decrease the power delivered to the load. For
example, if 2W is delivered from the device output to an
8I load through 100mI of total speaker trace, 1.97W is
delivered to the speaker. If power is delivered through
10mI of total speaker trace, 1.998W is delivered to the
speaker. Wide output, supply, and ground traces also
improve the power dissipation of the device.
The ICs are inherently designed for excellent RF immu-
nity. For best performance, add ground fills around all
signal traces on top or bottom PCB planes.
MAX98307/MAX98308
Charge-Pump Flying Capacitor
Charge-Pump Hold Capacitor
OVERALL GAIN (dB)
Layout and Grounding
11.5
14.5
17.5
20.5
8.5