MAX9714 Просмотр технического описания (PDF) - Maxim Integrated
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MAX9714 Datasheet PDF : 18 Pages
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6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. A
C1 value that is too small degrades the device’s ability to
provide sufficient current drive. Increasing the value of
C1 improves load regulation and reduces the charge-
pump output resistance to an extent. Above 1µF, the on-
resistance of the switches and the ESR of C1 and C2
dominate.
Output Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at CHOLD. Increasing C2 reduces output ripple.
Likewise, decreasing the ESR of C2 reduces both rip-
ple and output resistance. Lower capacitance values
can be used in systems with low maximum output
power levels.
Output Filter
The MAX9713/MAX9714 do not require an output filter.
The device passes FCC emissions standards with
36cm of unshielded speaker cables. However, output
filtering can be used if a design is failing radiated emis-
sions due to board layout or cable length, or the circuit
is near EMI-sensitive devices. Use a ferrite bead filter
when radiated frequencies above 10MHz are of con-
cern. Use an LC filter when radiated frequencies below
10MHz are of concern, or when long leads connect the
TOP VIEW
24 23 22 21 20 19 18 17
N.C. 25
16 G2
N.C. 26
15 G1
OUT- 27
14 SHDN
OUT- 28
OUT+ 29
MAX9713
13 SS
12 IN+
OUT+ 30
11 IN-
N.C. 31
10 AGND
N.C. 32
9 REG.
+1 2 3 4 5 6 7 8
amplifier to the speaker. Refer to the MAX9714
Evaluation Kit schematic for details of this filter.
Sharing Input Sources
In certain systems, a single audio source can be shared
by multiple devices (speaker and headphone ampli-
fiers). When sharing inputs, it is common to mute the
unused device, rather than completely shutting it down,
preventing the unused device inputs from distorting the
input signal. Mute the MAX9713/MAX9714 by driving SS
low through an open-drain output or MOSFET (see the
System Diagram). Driving SS low turns off the Class D
output stage, but does not affect the input bias levels of
the MAX9713/MAX9714. Be aware that during normal
operation, the voltage at SS can be up to 7V, depending
on the MAX9713/MAX9714 supply.
Supply Bypassing/Layout
Proper power-supply bypassing ensures low distortion
operation. For optimum performance, bypass VDD to
PGND with a 0.1µF capacitor as close to each VDD pin
as possible. A low-impedance, high-current power-sup-
ply connection to VDD is assumed. Additional bulk
capacitance should be added as required depending on
the application and power-supply characteristics. AGND
and PGND should be star connected to system ground.
Refer to the MAX9714 Evaluation Kit for layout guidance.
Pin Configurations
24 23 22 21 20 19 18 17
OUTR- 25
16 INR+
OUTR- 26
15 INR-
OUTR+ 27
14 REG.
OUTR+ 28
OUTL- 29
MAX9714
13 AGND
12 SS
OUTL- 30
11 SHDN
OUTL+ 31
10 INL+
OUTL+ 32
9 INL-
+1 2 3 4 5 6 7 8
TQFN (5mm x 5mm)
TQFN (7mm x 7mm)
Chip Information
MAX9713 TRANSISTOR COUNT: 3093
MAX9714 TRANSISTOR COUNT: 4630
PROCESS: BiCMOS
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