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Mono 2.6W Class D Amplifier

Detailed Description

The MAX98300 features industry-leading quiescent cur-

rent, 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 MAX98300 amplifier features click-and-pop sup-

pression that reduces audible transients on startup and

shutdown. The amplifier includes thermal overload and

short-circuit protection.

Class D Speaker Amplifier

The MAX98300 filterless Class D amplifier offers much

higher efficiency 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

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 89% efficiency.

Maxim’s patented spread-spectrum modulation mode

flattens wideband spectral components, while propri-

etary techniques ensure that the cycle-to-cycle variation

of the switching period does not degrade audio repro-

duction or efficiency. The MAX98300’s spread-spectrum

modulator randomly varies the switching frequency by

Q

10kHz 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 (2A typ), the MAX98300 disables the out-

puts for approximately 130Fs. At the end of 130Fs, the

outputs are re-enabled. If the fault condition still exists,

the MAX98300 continues to disable and re-enable the

outputs until the fault condition is removed.

Selectable Gain

The MAX98300 offers five programmable gain selections

through a single gain input (GAIN).

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

Table 1. Gain Control Configuration

FREQUENCY (MHz)

900

800

700

600

500

400

300

200

100

0

10

20

30

40

50

-10

30

1000

EN55022B LIMIT

GAIN PIN

MAXIMUM GAIN (dB)

Connect to PVDD

12

Connect to PVDD through

100kI

±5%

9

Not connected

6

Connect to PGND through

100kI

±5%

3

Connect to PGND

0