MAX9701 MAXIM [Maxim Integrated Products], MAX9701 Datasheet - Page 15

• Manufacturer Part Number: MAX9701
• Description: 1.3W, Filterless, Stereo Class D Audio Power Amplifier
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 8. 2.1 Channel Application Circuit
in portable devices typically have a poor response
below 300Hz. Taking these two factors into considera-
tion, the input filter may not need to be designed for a
20Hz to 20kHz response, saving both board space and
cost due to the use of smaller capacitors.
The MAX9701 does not require an output filter. The
device passes FCC emissions standards with 76mm of
unshielded speaker cables. However, output filtering
can be used if a design is failing radiated emissions due
to board layout or cable length, or if the circuit is near
EMI-sensitive devices. Use a ferrite bead filter when
radiated frequencies above 10MHz are of concern. Use
an LC filter or a common-mode choke when radiated
emissions below 10MHz are of concern, or when long
leads (>76mm) connect the amplifier to the speaker.
NOTE: VALUES SHOWN ARE FOR A LOWPASS CUTOFF OF 2Hz AND A BASS GAIN OF -1V/V.
FFM MODE WITH f
______________________________________________________________________________________
1.3W, Filterless, Stereo Class D Audio
OSC
= 1100kHz.
20kΩ
20kΩ
R1
R2
2200pF
2200pF
2200pF
2200pF
Output Filter
C
C
C
C
IN
IN
IN
IN
C2
0.01µF
INL+
INR+
INL-
INR-
SYNC
39kΩ
R4
1.25V
MAX9701
5V
SYNC_OUT
10kΩ
R3
The typical 2.1 channel application circuit (Figure 8)
shows the MAX9701 configured as a mid-/high-frequency
amplifier and the MAX9700 configured as a mono bass
amplifier. Input capacitors (C
frequency according to the following equation:
where R
MAX9701. The 10µF capacitors on the output of the
MAX9701 ensure a two-pole highpass filter.
OUTL+
OUTR+
OUTR-
OUTL-
MAX4238
1nF
C2
10µF
10µF
IN
8Ω
8Ω
is the typical input resistance of the
1µF
1µF
Power Amplifier
f
SYNC
IN+
IN-
=
2π
2.1 Channel Configuration
MAX9700
×
V
5V
DD
R
IN
1
IN
OUT+
OUT-
) set the highpass cutoff
×
C
IN
4Ω
15