LMX2485E EVAL National Semiconductor, LMX2485E EVAL Datasheet - Page 34

• Manufacturer Part Number: LMX2485E EVAL
• Description: BOARD EVALUATION LMX2485E
• Manufacturer: National Semiconductor
• Series: PLLatinum™r

Specifications of LMX2485E EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Utilized Ic / Part: LMX2485E
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

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2.6 R5 REGISTER
2.6.1 Fractional Numerator Determination { RF_FN[21:12], RF_FN[11:0], ACCESS[1] }
In the case that the ACCESS[1] bit is 0, then the part operates in 12-bit fractional mode, and the RF_FN2[21:12] bits become do
not care bits. When the ACCESS[1] bit is set to 1, the part operates in 22-bit mode and the fractional numerator is expanded from
12 to 22-bits.
2.6.2 Fractional Denominator Determination { RF_FD[21:12], RF_FD[11:0], ACCESS[1]}
In the case that the ACCESS[1] bit is 0, then the part is operates in the 12-bit fractional mode, and the RF_FD[21:12] bits become
do not care bits. When the ACCESS[1] is set to 1, the part operates in 22-bit mode and the fractional denominator is expanded
from 12 to 22-bits.
REGISTER
mer
ator
Den
ctio
ctio
omi
Fra
409
409
419
430
Fra
409
409
419
430
nal
nal
nat
Nu
or
...
...
...
...
0
1
5
6
3
0
1
5
6
3
R5
0
1
0
1
.
.
0
1
0
1
.
.
( These bits only apply in 22- bit mode)
( These bits only apply in 22- bit mode)
In 12- bit mode, these are do not care.
In 12- bit mode, these are do not care.
23
these bits should be all set to 0.
these bits should be all set to 0.
0
1
0
1
In 22- bit mode, for N <4096,
In 22- bit mode, for N <4096,
.
.
22
0
1
0
1
.
.
RF_FN[21:12]
RF_FD[21:12]
21
0
1
0
1
.
.
20
RF_FD[21:12]
0
1
0
1
.
.
19
0
1
0
1
.
.
18
0
1
0
1
.
.
17
0
1
0
1
16
.
.
DATA[19:0]
15
1
1
1
1
.
.
14
34
0
0
1
0
1
0
0
1
0
1
.
.
.
.
13
0
0
1
0
1
0
0
1
0
1
.
.
.
.
12
0
0
1
0
1
0
0
1
0
1
.
.
.
.
11
0
0
1
0
1
0
0
1
0
1
RF_FN[21:12]
.
.
.
.
10
0
0
1
0
1
0
0
1
0
1
.
.
.
.
RF_FN[11:0]
RF_FD[11:0]
9 8 7 6 5 4
0
0
1
0
1
0
0
1
0
1
.
.
.
.
0
0
1
0
1
0
0
1
0
1
.
.
.
.
0
0
1
0
1
0
0
1
0
1
.
.
.
.
0
0
1
0
1
0
0
1
0
1
.
.
.
.
C3
3
1
0
0
1
0
1
0
0
1
0
1
.
.
.
.
C2
2
0
0
0
1
0
1
0
0
1
0
1
.
.
.
.
C1
1
1
0
1
1
0
1
0
1
1
0
1
.
.
.
.
C0
0
1