MAX98304EWL 데이터 시트보기 (PDF) - Maxim Integrated

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MAX98304EWL

Mono 3.2W Class D Amplifier

Maxim Integrated 

MAX98304

Mono 3.2W Class D Amplifier

Shutdown

The IC features a low-power shutdown mode, drawing

less than 0.1FA (typ) of supply current. Drive SHDN low

to put the IC into shutdown.

Click-and-Pop Suppression

The IC speaker amplifier features Maxim’s comprehen-

sive 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 IC’s filterless modulation

scheme does not require an output filter.

Because the switching frequency of the IC 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

Power-Supply Input (PVDD)

PVDD powers the speaker amplifier. PVDD ranges

from 2.5V 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 CIN is:

CIN

=

2π × RIN[FF]

f−3dB

where f-3dB is the -3dB corner frequency and RIN is the

input resistance shown in the Electrical Characteristics

table. Use capacitors with adequately low voltage-coef-

ficient 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 the load

impedance decreases, the current drawn from the

device increases. At higher current, the resistance of the

output traces decreases the power delivered to the load.

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

to a 4I load through 100mI of total speaker trace,

1.904W is being delivered to the speaker. If power is

delivered through 10mI of total speaker trace, 1.99W

is being delivered to the speaker. Wide output, supply,

and ground traces also improve the power dissipation of

the device.

The IC is inherently designed for excellent RF immunity.

For best performance, add ground fills around all signal

traces on top or bottom PCB planes.

WLP Applications Information

For the latest application details on WLP construction,

dimensions, tape carrier information, PCB techniques,

bump-pad layout, and recommended reflow tempera-

ture profile, as well as the latest information on reliability

testing results, refer to Application Note 1891: Wafer-

level packaging (WLP) and its applications. Figure 2

shows the dimensions of the WLP balls used on the IC.

0.18mm

0.18mm

Figure 2. MAX98304 WLP Ball Dimensions

Maxim Integrated

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