M2006-02 Datasheet Rev 1.0
3 of 8
Revised 13Jul2004
M2006-02
VCSO BASED FEC CLOCK PLL
Prod uct Data Sh eet
PLL DIVIDER LOOK-UP TABLES
Mfin (Frequency Input) Divider Look-Up Table (LUT)
The FIN_SEL1:0 pins select the feedback divider value
(“Mfin”).
FEC PLL Ratio Dividers Look-up Table (LUT)
The FEC_SEL3:0 pins select the FEC feedback and
reference divider values Mfec and Rfec.
Post-PLL Dividers
The M2006-02 also features two post-PLL dividers,
one for each output pair. The “P1” divider is for FOUT1
and nFOUT1; the “P0” divider is for FOUT0 and nFOUT0.
Each divides the VCSO frequency to produce one of
two output frequencies (1/4 or 1/1 of the VCSO
frequency). The P1_SEL and P0_SEL pins each select the
value for their corresponding divider.
FUNCTIONAL DESCRIPTION
The M2006-02 is a PLL (Phase Locked Loop) based
clock generator that generates output clocks synchro-
nized to one of two selectable input reference clocks.
An internal high "Q" SAW filter provides low jitter signal
performance and controls the output frequency of the
VCSO (Voltage Controlled SAW Oscillator).
Configurable FEC feedback and reference dividers (the
“Mfec Divider” and “Rfec Divider”) provide the
multiplication ratios necessary to accomodate clock
translation for both forward and inverse Forward Error
Correction.
In addition, a configurable feedback divider (labeled
“Mfin Divider”) provides the broader division options
needed to accomodate various reference clock
frequencies.
For example, the M2006-02-622.0800 (see “Ordering on pg. 8) has a 622.08MHz VCSO frequency:
The inverse FEC PLL ratios (at top of Table 4) enable the M2006-02-622.0800 to accept “base” input reference
frequencies of: 663.7255, 666.5143, 669.3266,
672.1627
, and 622.08MHz.
The Mfin feedback divider enables the actual input
reference clock to be the “base” input frequency
divided by 1, 4, 8, or 32. Therefore, for the base input
frequency of 622.08MHz, the actual input reference
clock frequencies can be: 622.08, 155.52, 77.76, and
19.44
FIN_SEL1:0
Mfin Value
M2006-02-622.0800
Sample Ref. Freq. (MHz) 1
Note 1: Example with M2006-02-622.0800 and “Non-FEC ratio”
selection made from Table
4 (FEC_SEL2=1).
11
1
622.08 2
Note 2: Do not use with FEC_SEL3:0=1100 or 1101.
10
4
155.52
0
1
8
77.76
0
32
19.44
FEC_SEL3:0
Mfec Rfec1
Note 1: The phase detector frequency (Fpd, which is calculated as
Fref/Rfec) should be above 1.5 MHz to prevent spurs on the
output clock. To ensure the PLL remains locked when using a
recovered clock (such as in loop timing mode), the phase
detector frequency should ideally be about 20MHz, or at least
less than 50 MHz.
Description
0 0 0 0
236
255 Inverse FEC ratio
0 0 0 1
79
85
Inverse FEC ratio, equivalent to 237/255
0 0 1 0
14
15
Inverse FEC ratio, equivalent to 238/255
0 0 1 1
239
255 Inverse FEC ratio
0 1 0 0
236
236 Non-FEC ratio, complements 0000 or 1000
2
Note 2: These table selections use the same or similar Mfec divider
values as the complementary selections noted. This allows the
use of the same loop filter component values and resulting PLL
loop bandwidth and damping factor values for complementary
selections. Complementary selections can be actively
switched in a given application.
0 1 0 1
79
Non-FEC ratio, complements 0001 or 1001 2
0 1 1 0
14
Non-FEC ratio, complements 0010 or 1010 2
0 1 1 1
239
239 Non-FEC ratio, complements 0011 or 1011
2
1 0 0 0
255
236 FEC ratio (OTU3)
1 0 0 1
85
79
FEC ratio, equivalent to 255/237 (OTU2)
1 0 1 0
15
14
FEC ratio, equivalent to 255/238 (OTU1)
1 0 1 1
255
239 FEC ratio
1 1 0 0
1
Non-FEC ratio
3 Do not use these two settings
with FIN_SEL1:0=11
Note 3: In non-FEC applications, these settings can be used optimize
phase detector frequency or to actively change PLL loop
bandwidth.
1 1 0 1
2
1 1 1 0
4
Non-FEC ratio 3
1 1 1 1
8
P1_SEL, P0_SEL
P Value
M2006-02-622.0800
Output Frequency
(MHz)
1
4
155.52
0
1
622.08
Table 5: P Divider Selector, Values, and Frequencies