MAX98300 データシートの表示（PDF） - Maxim Integrated

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MAX98300

Mono 2.6W Class D Amplifier

Maxim Integrated 

MAX98300

Mono 2.6W Class D Amplifier

Shutdown

The MAX98300 features a low-power shutdown mode,

drawing less than 0.1FA of supply current. Drive SHDN

low to put the MAX98300 into shutdown.

Click-and-Pop Suppression

The MAX98300 speaker amplifier features Maxim’s com-

prehensive 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 ramp

down to PGND quickly and simultaneously.

Applications Information

Filterless Class D Operation

Traditional Class D amplifiers require an output filter.

The filter adds cost, size, and decreases efficiency and

THD+N performance. The MAX98300’s filterless modula-

tion scheme does not require an output filter (Figure 1).

Because the switching frequency of the MAX98300 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.

Component Selection

Speaker Amplifier Power Supply Input (PVDD)

PVDD powers the speaker amplifier. PVDD ranges

from 2.6V to 5.5V. Bypass PVDD with a 0.1FF and 10FF

capacitor to PGND. Apply additional bulk capacitance

at the device if long input traces between PVDD and the

power source are used.

Input Filtering

The input-coupling capacitor (CIN), in conjunction with the

amplifier’s internal input resistance (RIN), forms a high-

pass filter that removes the DC bias from the incoming

signal. These capacitors allow the amplifier to bias the

signal to an optimum DC level.

Assuming zero source impedance with a gain setting of

AV = 6dB, 9dB, or 12dB, CIN is:

= CIN

8 [µF]

f−3dB

with a gain setting of AV = 3dB, CIN is:

= CIN

5.7 [µF]

f−3dB

with a gain setting of AV = 0dB, CIN is:

= CIN

4 [µF]

f−3dB

where f-3dB is the -3dB corner frequency. Use capaci-

tors with adequately low voltage-coefficient for best low-

frequency THD performance.

Layout and Grounding

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

outputs increase. At higher current, the resistance of the

output traces decreases the power delivered to the load.

For example, if 2W is delivered from the speaker output

to a 4I load through a 100mI trace, 49mW is consumed

in the trace. If power is delivered through a 10mI trace,

only 5mW is consumed in the trace. Wide output, supply,

and ground traces also improve the power dissipation of

the device.

The MAX98300 is inherently designed for excellent RF

immunity. For best performance, add ground fills around

all signal traces on top or bottom PCB planes.

The MAX98300 TDFN-EP package features an exposed

thermal pad on its underside. This pad lowers the pack-

age’s thermal resistance by providing a heat conduction

path from the die to the PCB. Connect the exposed ther-

mal pad to the ground plane by using a large pad and

multiple vias.

Maxim Integrated

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