CDB44L11 Cirrus Logic Inc, CDB44L11 Datasheet - Page 3

• Manufacturer Part Number: CDB44L11
• Description: EVALUATION BOARD FOR CS44L11
• Manufacturer: Cirrus Logic Inc
• Series: Popguard®r

Specifications of CDB44L11

• Amplifier Type: Class D
• Output Type: Headphones, 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 23mW x 2 @ 16 Ohm
• Voltage - Supply: 1.8 V ~ 2.4 V
• Operating Temperature: -10°C ~ 70°C
• Board Type: Fully Populated
• Utilized Ic / Part: CS44L11
• Description/function: Audio DSPs
• Operating Supply Voltage: 5 V
• Product: Audio Modules
• For Use With/related Products: CS44L11
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

1. CDB44L11 SYSTEM OVERVIEW
The CDB44L11 is an excellent means of quickly demonstrating the CS44L11. The CS8420 dig-
ital audio interface receiver provides an interface to digital audio sources including the majority
of digital audio test equipment.
2. SCHEMATIC DESCRIPTIONS
2.1
The CS44L11, shown in Figure 1, can accept sampling frequencies varying from 8 kHz to 96 kHz
and can produce a PWM frequency ranging from 8 X Fs to 48 X Fs (refer to CS44L11
datasheet). In this design the 8 X Fs mode is used with a 48.25 kHz sample frequency (Fs),
which will result in a 386 kHz PWM switching frequency.
As shown in Figure 1, L3, L4, C29, and C30 form the 2nd order low pass LC filter for the output
audio. The following equations show how to calculate the filter values:
If you choose f
Choosing practical component values:
Output distortion is directly related to the inductor quality. The inductors should have a saturation
current of at least 150 mA for R
100 µH inductors for the output filter. 220 µF capacitors are used to block any DC signal from
being heard at the output. For maximum output power, low ESR capacitors should be used on
the output.
DS640DB1
C
L
C
L
C
L
filter
filter
filter
filter
filter
filter
CS44L11 Headphone Monitor and Output Filter
where:
= (1.414 * R
= (1.414 * 16) / (6.283 * 35000) = 102.881 µH
= 100 µH
= 0.707 / (6.283 * f
= 0.707 / (6.283 * 35000 * 16) = 0.2009 µF
= 0.22 µF
f
R
c
c
L
= 35 kHz, R
= desired -3 dB frequency of the filter
= the nominal speaker load impedance
L
) / (6.283 * f
c
L
= 16 W, then:
*R
L
L
= 16 Ω. This design uses the Central Technologies CTGSR74B
)
c
)
CDB44L11
3