DS3104 datasheet(39/136 Pages) MAXIM

39 / 136 page

________________________________________________________________________________________ DS3104-SE

19-4627; Rev 6; 5/09

39 of 136

7.8.2.3 OC1 to OC7 Configuration

The following is a step-by-step procedure for configuring the frequencies of output clocks OC1 to OC7:

1) Determine whether the T4 APLL must be independent of the T0 DPLL. If the T4 APLL must be

independent, set T4APT0 = 0 in register T0CR1. If the T4 APLL must be locked to the T0

DPLL, set T4APT0 = 1.

2) Use Table 7-9 to select a set of output frequencies for each APLL, T0 and T4. Each APLL can

only generate one set of output frequencies. (In SONET/SDH equipment, the T0 APLL is

typically configured for a frequency of 311.04MHz to get 19.44MHz and/or 38.88MHz output

clocks to distribute to system line cards.)

3) Determine from Table 7-9 the T0 and T4 APLL frequencies required for the frequency sets

chosen in step 2.

4) Configure the T0FREQ field in register T0CR1 as shown in Table 7-10 for the T0 APLL

frequency determined in step 3. Configure the T4FREQ field in register T4CR1 as shown in

Table 7-12 for the T4 APLL frequency determined in step 3. If the T4 APLL is locked to the T0

DPLL, the T4APT0 and T0FT4 fields in T0CR1 must also be configured as shown in Table

7-12.

5) Using Table 7-9 and Table 7-13, configure the frequencies of output clocks OC1 to OC7 in the

OFREQn fields of registers OCR1 to OCR4 and the AOFn bit in the OCR5 register.

Table 7-14 lists all standard frequencies for the output clocks and specifies how to configure the T0 APLL and/or

the T4 APLL to obtain each frequency. Table 7-14 also indicates the expected jitter amplitude for each frequency.

Table 7-7. Digital1 Frequencies

DIG1F[1:0]

SETTING IN

MCR7

DIG1SS

SETTING IN

MCR6

FREQUENCY

(MHz)

JITTER

(pk-pk ns,

typ)

2.048

< 1

4.096

< 1

8.192

< 1

16.384

< 1

1.544

< 1

3.088

< 1

6.176

< 1

12.352

< 1

Table 7-8. Digital2 Frequencies

DIG2AF

SETTING

IN MCR6

DIG2F[1:0]

SETTING

IN MCR7

DIG2SS

SETTING

IN MCR6

FREQUENCY

(MHz)

JITTER

(pk-pk

ns, typ)

6.312

< 1

10.000

19.440

< 1

38.880

< 1

2.048

< 1

4.096

< 1

8.192

< 1

16.384

< 1

1.544

< 1

3.088

< 1

6.176

< 1

12.352

< 1

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