MAX9779 查看數據表（PDF） - Maxim Integrated

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MAX9779

2.6W Stereo Audio Power Amplifier and DirectDrive Headphone Amplifier

Maxim Integrated 

2.6W Stereo Audio Power Amplifier and

DirectDrive Headphone Amplifier

ADDITIONAL THD+N DUE

TO DC-BLOCKING CAPACITORS

10

1

0.1

TANTALUM

0.01

0.001

ALUM/ELEC

0.0001

10

100

1k

10k

100k

FREQUENCY (Hz)

VDD

MAX9779 10µA

SHUTDOWN

CONTROL

HPS

20

HPOUTL

14

13

HPOUTR

1kΩ 1kΩ

Figure 4. Distortion Contributed by DC-Blocking Capacitors

Figure 5. HPS Configuration

Headphone Sense Input (HPS)

The headphone sense input (HPS) monitors the head-

phone jack and automatically configures the device

based upon the voltage applied at HPS. A voltage of

less than 0.8V sets the device to speaker mode. A volt-

age of greater than 2V disables the bridge amplifiers

and enables the headphone amplifiers.

For automatic headphone detection, connect HPS to the

control pin of a 3-wire headphone jack as shown in

Figure 5. With no headphone present, the output imped-

ance of the headphone amplifier pulls HPS low. When a

headphone plug is inserted into the jack, the control pin

is disconnected from the tip contact and HPS is pulled

to VDD through a 10µA current source.

BIAS

The MAX9779 features an internally generated, power-

supply independent, common-mode bias voltage of

1.8V referenced to GND. BIAS provides both click-and-

pop suppression and sets the DC bias level for the

amplifiers. Choose the value of the bypass capacitor as

described in the BIAS Capacitor section. No external load

should be applied to BIAS. Any load lowers the BIAS volt-

age, affecting the overall performance of the device.

Gain Selection

The MAX9779 features an internally set, selectable gain.

The GAIN1 and GAIN2 inputs set the maximum gain

of the MAX9779 speaker and headphone amplifiers

(Table 1).

Shutdown

The MAX9779 features a 0.2µA, low-power shutdown

mode that reduces quiescent current consumption and

extends battery life. Driving SHDN low disables the

drive amplifiers, bias circuitry, and charge pump, and

drives BIAS and all outputs to GND. Connect SHDN to

VDD for normal operation.

Click-and-Pop Suppression

Speaker Amplifier

The MAX9779 speaker amplifiers feature Maxim’s com-

prehensive, industry-leading click-and-pop suppres-

sion. During startup, the click-pop suppression circuitry

eliminates any audible transient sources internal to the

device. When entering shutdown, both amplifier out-

puts ramp to GND quickly and simultaneously.

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