CDB44L11 Cirrus Logic Inc, CDB44L11 Datasheet - Page 4

• 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

2.2
The provided MCLK oscillator frequency is 12.352 MHz. Any oscillator between 6.4 MHz and
24.576 MHz may be used in the socket. The MCLK signal is divided by the clock divider to pro-
duce SCLK (MCKL/4), and LRCK (MCKL/256). Using a 12.352 MHz MCLK, SCLK is 3.088 MHz,
and LRCK is 48.25 kHz.
2.3
Refer to Figure 2. The CS8420 is a S/PDIF receiver and sample rate converter. It is configured
to accept data at any sample rate between 32 kHz and 96 kHz and transmits data in PCM audio
data format based on the MCLK oscillator frequency. The CS8420, while not required, improves
system performance by reducing clock jitter and providing one fixed output frequency. In this de-
sign, the 48.25 kHz sample rate was chosen so that the CS8420 does not perform 1:1 conversion
when receiving 48 kHz input data. Noise can be introduced into the system when a 1:1 conver-
sion is performed and should be avoided for optimal performance. For more information please
refer to the CS8420 datasheet.
2.4
Figure 3 shows the host microcontroller circuitry. There are 8 buttons for control features, 5 LEDs
to indicate status, and an I
tial CS44L11 register settings. After power is first applied to the board or the reset button is
pressed, all settings will revert to the default settings.
The board is populated with a Motorola MC68HC908GP32 with the software preprogrammed to
run the CDB44L11. The microcontroller code was written in C and compiled with the 'COSMIC
C Compiler'.
The microcontroller uses the I
- refer to CS44L11 data sheet for more information.
2.5
Figure 4 shows the power supply and level shifting circuitry. Due to the CS44L11 operating at
below +5.0 V, level-shifting circuitry has been included to allow for operation with the microcon-
troller and the CS8420, both of which must run at +5.0 V.
The CS44L11 uses a half bridge output stage and is therefore affected by power supply pumping.
Power supply pumping is a phenomenon observed in half-bridge switching amplifiers. It is
caused by stored energy in the output inductor that is fed back into the power supply during
switching. To compensate for power supply pumping, a resistive load is used to dissipate the
4
Clocking
CS8420 Sample Rate Converter
Microcontroller
Power Supplies and Level-Shifting
2
C interface to the CS8420 and the CS44L11. See Table 3 for the ini-
2
C control bus to read and write to the CS44L11 control registers
CDB44L11
DS640DB1