MAX9750 查看數據表（PDF） - Maxim Integrated

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MAX9750

2.6W Stereo Audio Power Amplifiers and DirectDrive Headphone Amplifiers

Maxim Integrated 

2.6W Stereo Audio Power Amplifiers and

DirectDrive Headphone Amplifiers

MAX9750A

VOLUME CONTROL TRANSFER FUNCTION

20

GAIN1 = GAIN2 = 0

10

0

-10

SPEAKER MODE

AUDIO

-20

TAPER POT

-30

-40

-50

HEADPHONE MODE

-60

-70

-80

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

VVOL (V)

Figure 7a. Volume Control Transfer Function

MAX9750C

VOLUME CONTROL TRANSFER FUNCTION

20

GAIN1 = GAIN2 = 0

10

0

-10

SPEAKER MODE

-20

AUDIO

-30

TAPER POT

-40

-50

HEADPHONE MODE

-60

-70

-80

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

VVOL (V)

Figure 7c. Volume Control Transfer Function

MAX9750B

VOLUME CONTROL TRANSFER FUNCTION

20

GAIN1 = GAIN2 = 0

10

0

SPEAKER MODE

-10

-20

AUDIO

TAPER POT

-30

-40

-50

-60

HEADPHONE MODE

-70

-80

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

VVOL (V)

Figure 7b. Volume Control Transfer Function

Headphone Amplifier

In conventional single-supply headphone amplifiers,

the output-coupling capacitor is a major contributor of

audible clicks and pops. Upon startup, the amplifier

charges the coupling capacitor to its bias voltage, typi-

cally half the supply. Likewise, during shutdown, the

capacitor is discharged to GND. A DC shift across the

capacitor results, which in turn appears as an audible

transient at the speaker. Since the MAX9750/MAX9751/

MAX9755 do not require output-coupling capacitors, no

audible transient occurs.

Additionally, the MAX9750/MAX9751/MAX9755 features

extensive click-and-pop suppression that eliminates

any audible transient sources internal to the device.

The Power-Up/Down Waveform in the Typical

Operating Characteristics shows that there are minimal

spectral components in the audible range at the output

upon startup and shutdown.

0.47µF

SOURCE 1

0.47µF

SOURCE 2

0.47µF

SOURCE 3

RS1

47kΩ

RS2

47kΩ

RS3

47kΩ

RINT

47kΩ

BEEP

BIAS

VOUT(BEEP)

WINDOW

DETECTOR

(0.3VP-P THRESHOLD)

FREQUENCY

DETECTOR

(300Hz THRESHOLD)

SPEAKER/HEADPHONE

AMPLIFER INPUTS

MAX9750

Figure 8. Beep Input

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