MAX9737 데이터 시트보기 (PDF) - Maxim Integrated

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MAX9737

Mono 7W Class D Amplifier

Maxim Integrated 

Mono 7W Class D Amplifier

PIN

1, 17, 18

2

3, 10, 11

4

5

6

7

8

9

12

13, 14

15

16

19, 20

21, 22

23, 24

—

NAME

PVDD

CHOLD

AGND

MUTE

SHDN

PC

IN

PRE

COM

REG

VS

C1N

C1P

OUT-

PGND

OUT+

EP

Pin Description

FUNCTION

Power Supply. Bypass PVDD to PGND with a 1µF capacitor connected to pin 1 and a 1µF capacitor

connected to pins 17 and 18.

Charge-Pump Output. Connect a 1µF capacitor to PVDD.

Analog Ground

Mute Input. Drive MUTE low to place the device in mute mode.

Shutdown Input. Drive SHDN low to place the part in shutdown mode.

Input Capacitor Precharge Connection. Connect between input resistor, RIN, and input coupling

capacitor, CIN.

Op Amp Inverting Input.

Op Amp Output. PRE is the output of the input operational amplifier.

Internal 2.0V Bias. Bypass COM to AGND with a 1µF capacitor.

Internal 4.2V Bias. Bypass REG to AGND with a 1µF capacitor.

Internal 5.0V Bias. Bypass VS to AGND with a 1µF capacitor.

Charge-Pump, Flying-Capacitor Negative Terminal. Connect C1N to C1P through a 0.1µF capacitor.

Charge-Pump, Flying-Capacitor Positive Terminal. Connect C1P to C1N through a 0.1µF capacitor.

Negative Speaker Output

Power Ground

Positive Speaker Output

Exposed Pad. Must be externally connected to PGND.

Detailed Description

The MAX9737 filterless, mono class D audio power

amplifier offers Class AB audio performance and Class

D efficiency with minimal board space. The device

operates from an 8V to 28V supply range.

The MAX9737 features filterless, spread-spectrum

modulation, externally set gain and a low-power shut-

down mode that reduces supply current to less than

1µA. Comprehensive click-and-pop suppression and

precharge circuitry reduce noise into and out of shut-

down or mute within 10ms.

Spread-Spectrum Modulation

The MAX9737 features a unique, patented spread-

spectrum switching modulation that flattens EMI wide-

band spectral components, reducing radiated

emissions from the speaker and cables. The switching

frequency of the Class D amplifier varies randomly by

±4kHz around the 300kHz center frequency. Instead of

a large amount of spectral energy present at multiples

of the switching frequency, the energy is spread over a

bandwidth that increases with frequency. Above a few

MHz, the wideband spectrum looks like white noise for

EMI purposes. A proprietary amplifier topology ensures

this white noise does not corrupt the noise floor in the

audio bandwidth.

Efficiency

The high efficiency of a Class D amplifier is due to the

output transistors acting as switches and therefore con-

sume negligible power. Power loss associated with the

Class D output stage is due to the MOSFET I2R losses,

switching losses, and quiescent current.

Although the theoretical best efficiency of a linear

amplifier is 78% at peak output power, under typical

music reproduction levels, the efficiency falls to below

40%. The MAX9737 exhibits > 80% efficiency under the

same conditions (Figure 1).

Shutdown

The MAX9737 features a shutdown mode that reduces

power consumption to less than 1µA (typ), extending

battery life in portable applications. Drive SHDN low to

place the device in low-power shutdown mode. In shut-

down mode, the outputs are high impedance and the

common-mode voltage at the output decays to zero.

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