18

DS786A1

CS4412A

4.4.2

Full-Bridge Output Filter (Stereo or Parallel)

Figure 6 shows the output filter for a full-bridge configuration. The transient-voltage suppression circuit

(snubber circuit) is comprised of a resistor (20

Ω) and capacitor (330 pF) and should be placed as close

as possible to the corresponding PWM output pins to greatly reduce radiated EMI. The inductors, L1 and

L2, and capacitor, C1, comprise the low-pass filter. Along with the nominal load impedance of the speaker,

these values set the cutoff frequency of the filter. Table 6 shows the component values based on nominal

speaker (load) impedance for a corner frequency (-3 dB point) of approximately 35 kHz.

Each output pin must be connected to two Schottky diodes—one to ground and one to the VP supply.

These diodes should be placed within 12 mm of the corresponding OUTx pin. The requirements of this

diode are:

Load

L1, L2

C1

4

Ω

10 µH

1.0 µF

6

Ω

15 µH

0.47 µF

8

Ω

22 µH

0.47 µF

Table 6. Low-Pass Filter Components - Full-Bridge

OUTX+

OUTX-

330 pF

20

Ω

C1

L1

L2

*Diode is Rohm

RB160M-30 or

equivalent

VP

VP

Figure 6. Output Filter - Full-Bridge