cs4412a Cirrus Logic, Inc., cs4412a Datasheet - Page 16

• Manufacturer Part Number: cs4412a
• Description: 30w Quad Half-bridge Digital Amplifier Power Stage
• Manufacturer: Cirrus Logic, Inc.

16
4.4
4.4.1
Output Filters
The filter placed after the PWM outputs can greatly affect the output performance. The filter not only reduces
radiated EMI (snubber filter) but also filters high frequency content from the switching output before going
to the speaker (low-pass LC filter).
Half-Bridge Output Filter
Figure 5
(snubber circuit) is comprised of a capacitors (680 pF) and a resistor (5.6 Ω, 1/8 W) and should be placed
as close as possible to the corresponding PWM output pin to greatly reduce radiated EMI.
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:
1. Rated I
2. Support up to 80°C of lead temperature with V
3. V
The inductor, L1, and capacitor, C1, comprise the low-pass filter. Along with the nominal load impedance
of the speaker, these values set the cut-off frequency of the filter.
for L1 and C1 based on nominal speaker (load) impedance for a corner frequency (-3 dB point) of approx-
imately 35 kHz.
at the corresponding I
R
(reverse voltage) is greater than or equal to 20 V.
shows the output filter for a half-bridge configuration. The transient-voltage suppression circuit
F
(average rectifier forward current) is greater than or equal to 1.0 A.
OUTx
F
.
Table 4. Low-Pass Filter Components - Half-Bridge
Load
4 Ω
6 Ω
8 Ω
680 pF
5.6 Ω
Figure 5. Output Filter - Half-Bridge
VP
22 µH
33 µH
47 µH
*Diode is Rohm
F
RB160M-30 or
L1
drop (forward voltage) less than or equal to 480 mV
equivalent
L1
Table 4
0.68 µF
0.47 µF
1.0 µF
C1
C1
+
C2
shows the component values
-
CS4412A
DS786A2