MAX98304 データシートの表示（PDF） - Maxim Integrated

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MAX98304

Mono 3.2W Class D Amplifier

Maxim Integrated 

MAX98304

Mono 3.2W Class D Amplifier

Detailed Description

The MAX98304 features low quiescent current, a low-

power shutdown mode, comprehensive click-and-pop

suppression, and excellent RF immunity.

The device offers Class AB audio performance with

Class D efficiency in a minimal board-space solution.

The Class D amplifier features spread-spectrum modula-

tion, edge-rate, and overshoot control circuitry that offers

significant improvements to switch-mode amplifier radi-

ated emissions.

The amplifier features click-and-pop suppression that

reduces audible transients on startup and shutdown.

The amplifier includes thermal overload and short-circuit

protection.

Class D Speaker Amplifier

The filterless Class D amplifier offers much higher effi-

ciency than Class AB amplifiers. The high efficiency of

a Class D amplifier is due to the switching operation of

the output stage transistors. Any power loss associated

with the Class D output stage is mostly due to the I2R

loss of the MOSFET on-resistance and quiescent current

overhead.

Ultra-Low EMI Filterless Output Stage

Traditional Class D amplifiers require the use of external

LC filters, or shielding, to meet EN55022B electromag-

netic-interference (EMI) regulation standards. Maxim’s

patented active emissions-limiting edge-rate control

circuitry and spread-spectrum modulation reduces EMI

emissions, while maintaining up to 93% efficiency.

Maxim’s patented spread-spectrum modulation mode

flattens wideband spectral components, while propri-

etary techniques ensure that the cycle-to-cycle varia-

tion of the switching period does not degrade audio

reproduction or efficiency. The IC’s spread-spectrum

modulator randomly varies the switching frequency by

Q12.5kHz around the center frequency (300kHz). Above

10MHz, the wideband spectrum looks like noise for EMI

purposes (Figure 1).

Speaker Current Limit

If the output current of the speaker amplifier exceeds the

current limit (2.8A typ), the IC disables the outputs for

approximately 100Fs. At the end of 100Fs, the outputs

are reenabled. If the fault condition still exists, the IC

continues to disable and reenable the outputs until the

fault condition is removed.

Selectable Gain

The IC offers five programmable gain selections through

a single gain input (GAIN).

Table 1. Gain Control Configuration

GAIN PIN

Connect to PGND

MAXIMUM GAIN (dB)

12

Connect to PGND through

100kW ±5% resistor

9

Connect to PVDD

6

Connect to PVDD through

100kW ±5% resistor

3

Unconnected

0

90

70

50

EN55022B LIMIT

30

HORIZONTAL

10

VERTICAL

-10

0 100 200 300 400 500 600 700 800 900 1000

FREQUENCY (MHz)

Figure 1. EMI with 60cm of Speaker Cable and No Output Filtering

8  

Maxim Integrated

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