UDA1325 データシートの表示（PDF） - Philips Electronics
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UDA1325 Datasheet PDF : 52 Pages
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Philips Semiconductors
Universal Serial Bus (USB) CODEC
Preliminary specification
UDA1325
The clock source of the analog-to-digital interface
The clock source of the ADIF is the analog PLL or the ADC oscillator. The preferred clock source can be selected.
The ADC clock used for the ADC and decimation filters is obtained by dividing the clock signal coming from the analog
PLL or from the ADC oscillator by a factor Q.
Using the analog PLL the user can select 3 basic APLL clock frequencies (see Table 1).
By connecting the appropriate crystal the user can choose any clock signal between 8.192 and 14.08 MHz via the ADC
oscillator.
Table 1 The analog PLL clock output frequencies
FCODE (1 AND 0)
00
01
10
11
APLL CLOCK
FREQUENCY (MHz)
11.2896
8.1920
12.2880
11.2896
The dividing factor Q can be selected via the microcontroller. With this dividing factor Q the user can select a range of
ADC clock signals allowing several different sample frequencies (see Table 2).
Table 2 ADC clock frequencies and sample frequencies based upon using the APLL as a clock source
APLL CLOCK
FREQUENCY (MHz)
8.1920
11.2896
12.2880
DIVIDE FACTOR Q ADC CLOCK FREQUENCY (MHz) SAMPLE FREQUENCY (kHz)
1
4.096
32
2
2.048
16
4
1.024
8
8
0.512 (not supported)
4 (not supported)
1
5.6448
44.1
2
2.8224
22.05
4
1.4112
11.025
8
0.7056
5.5125
1
6.144
48
2
3.072
24
4
1.536
12
8
0.768
6
Table 3 ADC clock frequencies and sample frequencies based upon using the OSCAD as a clock source
OSCAD CLOCK
FREQUENCY (MHz)
fosc(1)
DIVIDE FACTOR Q ADC CLOCK FREQUENCY (MHz) SAMPLE FREQUENCY (kHz)
Q(2)
fosc/(2Q)
fosc/(256Q)(3)
Notes
1. The oscillator frequency (and therefore the crystal) of OSCAD must be between 8.192 and 14.08 MHz.
2. The Q factor can be 1, 2, 4 or 8.
3. Sample frequencies below 5 kHz and above 55 kHz are not supported.
1999 May 10
11
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