MAX9723 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX9723

Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C

Maxim Integrated 

MAX9723

Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I2C

Pin Description

PIN

THIN QFN

1

2

3

4

5

6

7

BUMP

UCSP

D1

C1

B1

A1

B2

A2

A3

8

B3

9

A4

10

B4

11

C4

12

D4

13

C3

14

D3

15

D2

16

C2

EP

—

NAME

VDD

C1P

PGND

C1N

SCL

PVSS

SDA

SHDN

SGND

INL

INR

SVSS

BBR

OUTR

OUTL

BBL

EP

FUNCTION

Power-Supply Input. Bypass VDD to PGND with a 1µF capacitor.

Charge-Pump Flying Capacitor Positive Terminal

Power Ground. Connect to SGND.

Charge-Pump Flying Capacitor Negative Terminal

Serial Clock Input. Connect a 10kI pullup resistor from SCL to VDD.

Charge-Pump Output. Connect to SVSS. Bypass PVSS with a 1µF capacitor to PGND.

Serial-Data Input. Connect a 10kΩ pullup resistor from SDA to VDD.

Shutdown. Drive SHDN low to disable the MAX9723. Connect SHDN to VDD while bit 7

is high for normal operation (see the Command Register section).

Signal Ground. Connect to PGND.

Left-Channel Input

Right-Channel Input

Headphone Amplifier Negative Power-Supply Input. Connect to PVSS.

Right BassMax Input. Connect an external lowpass filter between OUTR and BBR to

apply bass boost to the right-channel output. Connect BBR to SGND if BassMax is not

used (see the BassMax (Bass Boost) section).

Right Headphone Output

Left Headphone Output

Left BassMax Input. Connect an external lowpass filter between OUTL and BBL to

apply bass boost to the left-channel output. Connect BBL to SGND if BassMax is not

used (see the BassMax (Bass Boost) section).

Exposed Paddle. Connect EP to SVSS or leave unconnected.

Detailed Description

The MAX9723 stereo headphone amplifier features

Maxim’s DirectDrive architecture, eliminating the large

output-coupling capacitors required by conventional sin-

gle-supply headphone amplifiers. The MAX9723 consists

of two 62mW Class AB headphone amplifiers, hardware/

software shutdown control, inverting charge pump, inte-

grated 32-level volume control, BassMax circuitry, com-

prehensive click-and-pop suppression circuitry, and an

I2C-compatible interface (see the Functional Diagram/

Typical Operating Circuit). A negative power supply

(PVSS) is created internally by inverting the positive sup-

ply (VDD). Powering the amplifiers from VDD and PVSS

increases the dynamic range of the amplifiers to almost

twice that of other single-supply amplifiers, increasing the

total available output power.

The MAX9723 DirectDrive outputs are biased at SGND

(see Figure 1). The benefit of this 0V bias is that the ampli-

fier outputs do not have a DC component, eliminating the

need for large DC-blocking capacitors. Eliminating the

DC-blocking capacitors on the output saves board space,

system cost, and improves low-frequency response.

An I2C-compatible interface allows serial communica-

tion between the MAX9723 and a microcontroller. The

MAX9723 is available with two different I2C addresses

allowing two MAX9723 ICs to share the same bus (see

Table 1). The internal command register controls the

shutdown status of the MAX9723, enables the BassMax

circuitry, sets the maximum gain of the amplifier, and sets

the volume level (see Table 2). The MAX9723’s BassMax

circuitry improves audio reproduction by boosting the

bass response of the amplifier, compensating for any low-

frequency attenuation introduced by the headphone. The

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