MAX9711ETC(2008) Просмотр технического описания (PDF) - Maxim Integrated

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производитель

MAX9711ETC
(Rev.:2008)

3W Mono/Stereo BTL Audio Power Amplifiers with Shutdown

Maxim Integrated 

3W Mono/Stereo BTL Audio Power Amplifiers

with Shutdown

TOTAL HARMONIC DISTORTI0N PLUS NOISE

vs. FREQUENCY

10

VOUT = 8VP-P

1

0.1

15kΩ

1μF 15kΩ

AUDIO

INPUT

2 IN

10Ω

OUT+ 4

100μH

*

0.01

0.001

0.01

0.1

1

10

100

FREQUENCY (Hz)

Figure 2. MAX9711 Piezoelectric Speaker Driver THD+N vs.

Frequency

The capacitive nature of the piezoelectric speaker may

cause the MAX9711 to become unstable. A simple induc-

tor/resistor network in series with the speaker isolates the

speaker capacitance from the driver and ensures that the

device output sees a resistive load of about 10Ω at high

frequency, thereby maintaining stability (Figure 3).

Layout and Grounding

Good PC board layout is essential for optimizing perfor-

mance. Use large traces for the power-supply inputs and

amplifier outputs to minimize losses due to parasitic

trace resistance and route heat away from the device.

Good grounding improves audio performance,

minimizes crosstalk between channels, and prevents any

digital switching noise from coupling into the audio

signal.

The MAX9710/MAX9711 thin QFN package features an

exposed thermal pad on the underside. This pad low-

ers the thermal resistance of the package by providing

a direct-heat conduction path from the die to the print-

ed circuit board. Connect the exposed pad to the

ground plane using multiple vias, if required. For opti-

mum performance, connect to the ground planes as

shown in Figure 4.

OUT- 12

MAX9711

*PIEZOELECTRIC

SPEAKER.

Figure 3. Isolation Network for Driving a Piezoelectric Speaker

5V

PVDD

VDD

PGND

MAX9710

FOR OPTIMUM PERFORMANCE,

AUDIO GND SHOULD HAVE A

STAR CONNECTION TO THE HIGH

CURRENT, AMPLIFIER PGND AT

A SINGLE POINT, PIN 6.

AUDIO SIGNAL

GND

Figure 4. MAX9710 Audio Ground Connection

_______________________________________________________________________________________ 9

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