
DS3106
27
7.8.2.3 OC3 and OC6 Configuration
The following is a step-by-step procedure for configuring the frequencies of output clocks OC3 and OC6:
Use
Table 7-8 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 N x 19.44MHz output clocks to for use on line cards.)
Determine from
Table 7-8 the T0 and T4 APLL frequencies required for the frequency sets chosen in step
2.
Configure the T0FREQ field in register
T0CR1 as shown in
Table 7-9 for the T0 APLL frequency
in
Table 7-11 for the T4 APLL frequency determined in step 3.
Using
Table 7-8 and
Table 7-12, configure the frequencies of output clocks OC3 and OC6 in the OFREQn
fields of registers
OCR2 and
OCR4 and the AOFn bits in the
OCR5 register.
Table 7-13 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 7-13 also indicates the expected jitter amplitude for each frequency.
Table 7-6. Digital1 Frequencies
DIG1F[1:0]
SETTING IN
DIG1SS
SETTING IN
FREQUENCY
(MHz)
JITTER
(pk-pk, ns,
typ)
00
0
2.048
< 1
01
0
4.096
< 1
10
0
8.192
< 1
11
0
16.384
< 1
00
1
1.544
< 1
01
1
3.088
< 1
10
1
6.176
< 1
11
1
12.352
< 1
Table 7-7. Digital2 Frequencies
DIG2AF
SETTING
DIG2F[1:0]
SETTING
DIG2SS
SETTING
FREQUENCY
(MHz)
JITTER
(pk-pk,
ns, typ)
1
00
0
6.312
< 1
1
10
0
10.000
<1
1
00
1
19.440
< 1
1
01
1
38.880
< 1
0
00
0
2.048
< 1
0
01
0
4.096
< 1
0
10
0
8.192
< 1
0
11
0
16.384
< 1
0
00
1
1.544
< 1
0
01
1
3.088
< 1
0
10
1
6.176
< 1
0
11
1
12.352
< 1