MAX9879(2009) データシートの表示（PDF） - Maxim Integrated

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MAX9879
(Rev.:2009)

Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier

Maxim Integrated 

Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

BUMP

A1

A2

A3

A4

A5, B5

A6

B1

B2

B3

B4

B6

C1

C2, C3, C4,

C5

C6

D1

D2

D3

D4

D5

D6

E1

E2

E3

E4

E5

E6

NAME

C1P

OUTL-

PVDDL

OUTL+

PGNDR

OUTR-

C1N

RXIN-

PGNDL

RXIN+

PVDDR

VSS

GND

OUTR+

HPL

BIAS

INB1

INA1

SCL

SDA

HPR

VDD

INB2

INA2

SHDN

VCCIO

Pin Description

FUNCTION

Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.

Left-Speaker Negative Output

Left-Channel Class D Power Supply. Bypass with a 1µF capacitor to PGNDL.

Left-Speaker Positive Output

Right-Channel Class D Power Ground

Right-Speaker Negative Output

Charge-Pump Flying Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.

Receiver Bypass Negative Input

Left-Channel Class D Power Ground

Receiver Bypass Positive Input

Right-Channel Class D Power Supply. Bypass with a 1µF capacitor to PGNDL.

Headphone Amplifier Negative Power Supply. Bypass with a 1µF capacitor to PGND.

Analog Ground

Right-Speaker Positive Output

Headphone Amplifier Right Output

Common-Mode Bias. Bypass to GND with a 1µF capacitor.

Input B1. Left input or negative input.

Input A1. Left input or negative input.

Serial-Clock Input. Connect a pullup resistor from SDA to VCCIO.

Serial-Data Input/Output. Connect a pullup resistor from SDA to VCCIO.

Headphone Amplifier Left Output

Analog Supply. Connect to PVDDL and PVDDR. Bypass with a 1µF capacitor to GND.

Input B2. Right input or positive input.

Input A2. Right input or positive input.

Active-Low Shutdown Input Signal

I2C Power Supply

Detailed Description

Signal Path

The MAX9879 signal path consists of flexible inputs,

signal mixing, volume control, and output amplifiers

(Figures 1a, 1b, 1c).

The inputs can be configured for single-ended or differ-

ential signals (Figure 2). The internal preamplifiers fea-

ture three programmable gain settings of 0dB, +5.5dB,

and +20dB. Following preamplification, the input sig-

nals are mixed, volume adjusted, and routed to the

headphone and speaker amplifiers based on the out-

put mode configuration (see Table 6). The volume con-

trol stages provide up to 75dB attenuation. The

headphone amplifiers provide +3dB of gain while the

speaker amplifier provides +18dB of additional gain.

When an input is configured as mono differential, it can

be routed to both speakers or to both headphones.

When an input is stereo, it is routed to either the stereo

headphones or the stereo speakers. Simultaneous oper-

ation is also possible. If the right speaker amplifier is dis-

abled then the left and right audio signals are summed

into the left speaker amplifier and vice-versa.

When the application does not require the use of both

INA_ and INB_, the SNR of the MAX9879 is improved

by deselecting the unused input through the I2C output

mode register and AC-coupling the unused inputs to

ground with a 330pF capacitor. The 330pF capacitor

and the input resistance to the MAX9879 form a high-

pass filter preventing audible noise from coupling into

the outputs.

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