lm49370rl National Semiconductor Corporation, lm49370rl Datasheet - Page 22

• Manufacturer Part Number: lm49370rl
• Description: Audio Sub-system With An Ultra Low Emi, Spread Spectrum, Class D Loudspeaker Amplifier, A Dual-mode Stereo Headphone Amplifier, And A Dedicated Pcm Interface For Bluetooth Transceivers
• Manufacturer: National Semiconductor Corporation

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12.4 COMMON CLOCK SETTINGS FOR THE DAC & ADC
When DAC_MODE = '00' (bits 7:6 of (0x00h)), the DAC has an over sampling ratio of 125 but requires a 250*fs clock at point B.
This allows a simple clocking solution as it will work from 12.000 MHz (common in most systems with Bluetooth or USB) at 48 kHz
exactly, the following table describes the clock required at point B for various clock sample rates in the different DAC modes:
Note: When DAC_MODE = '01' with the I
of the clock at point B. This divided by two DAC clock is used as the source clock for the audio port.
The over sampling ratio of the ADC is set by ADC MODE (bit 0 of 0x07h)). The table below shows the required clock frequency at
point C for the different ADC modes.
Methods for producing these clock frequencies are described in the PLL Section.
DAC Sample Rate (kHz)
ADC Sample Rate (kHz)
11.025
11.025
22.05
22.05
44.1
12
16
24
32
48
12
16
24
8
8
Clock Required at B (OSR = 125)
Clock Required at C (OSR = 125)
TABLE 4. Common DAC Clock Frequencies
TABLE 5. Common ADC Clock Frequencies
2
S or PCM interface operating as master, the stereo DAC operates at half the frequency
1.378125 MHz
2.75625 MHz
2.75625 MHz
5.5125 MHz
11.025 MHz
1.5 MHz
12 MHz
2 MHz
3 MHz
4 MHz
6 MHz
8 MHz
1 MHz
2 MHz
3 MHz
22
Clock Required at B (OSR = 128)
Clock Required at C (OSR = 128)
11.2896 MHz
2.8224 MHz
5.6448 MHz
12.288 MHz
1.4112 MHz
2.8224 MHz
2.048 MHz
3.072 MHz
4.096 MHz
6.144 MHz
8.192 MHz
1.024 MHz
1.536 MHz
2.048 MHz
3.072 MHz