MAX9736(2008) データシートの表示（PDF） - Maxim Integrated

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MAX9736
(Rev.:2008)

Mono/Stereo High-Power Class D Amplifier

Maxim Integrated 

Mono/Stereo High-Power Class D Amplifier

Click-and-Pop Suppression

The MAX9736 features comprehensive click-and-pop

suppression that minimizes audible transients on start-

up and shutdown. While in shutdown, the H-bridge is in

a high-impedance state.

Mono Configuration

The MAX9736 features a mono mode that allows the

right and left channels to operate in parallel, achieving

up to 30W (MAX9736A) of output power. Apply a logic-

high to MONO to enable mono mode. In mono mode,

an audio signal applied to the left channel (INL) is rout-

ed to the H-bridges of both channels. Also in mono

mode, the right-channel preamplifier becomes an

uncommitted operational amplifier, allowing for flexibili-

ty in system design. Connect OUTL+ to OUTR+ and

OUTL- to OUTR- using heavy PCB traces as close as

possible to the device. Driving MONO low (stereo

mode) while the outputs are wired together in mono

mode can trigger the short-circuit or thermal-overload

protection or both.

Current Limit

When the output current reaches the current limit, 4.6A

(typ), the MAX9736 disables the outputs and initiates a

450µs startup sequence. The shutdown and startup

sequence is repeated until the output fault is removed.

Properly designed applications do not enter current-

limit mode unless the output is short circuited or con-

nected incorrectly.

Thermal Shutdown

When the die temperature reaches the thermal shut-

down threshold, +160°C (typ), the MAX9736 outputs

are disabled. When the die temperature decreases by

30°C, normal operation resumes. Some causes of ther-

mal shutdown are excessively low load impedance,

poor thermal contact between the MAX9736‘s exposed

pad and the PCB, elevated ambient temperature, or

poor PCB layout and assembly.

Applications Information

Filterless Class D Operation

The MAX9736 meets EN55022B EMC radiation limits

with an inexpensive ferrite bead and capacitor filter

when the speaker leads are less than or equal to 1m.

Select a ferrite bead with 100Ω to 600Ω impedance

and rated for at least 2A. The capacitor value varies

based on the ferrite bead chosen and the speaker lead

length. See Figure 3 for the correct connections of

these components.

40

35

30

25

20

15

10

5

30

EN55022B LIMIT

100 200 300 400 500 600 700 800 900 1000

FREQUENCY (MHz)

Figure 2. EMI Performance

MAX9736

FB1

FB2

C1

C2

330pF

330pF

FB1 AND FB2 = WURTH 742792040

Figure 3. Ferrite Bead Filter

MAX9736

C2

C4

R1

L1

C1

L2

C3

C5

R2

Figure 4. Output Filter for PWM Mode

When evaluating the MAX9736 with a ferrite bead filter

and resistive load, include a series inductor (68µH for

8Ω load and 33µH for 4Ω load) to model the actual

loudspeaker’s behavior. Omitting the series inductor

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