LMX2355SLB National Semiconductor, LMX2355SLB Datasheet - Page 18

• Manufacturer Part Number: LMX2355SLB
• Description: PLLatinum Fractional N RF/ Integer N IF Dual Low Power Frequency Synthesizer
• Manufacturer: National Semiconductor

www.national.com
Programming Description
5.2.2 N REGISTER — (8/9/12/13) PRESCALER OPERATING IN FRACTIONAL MODE
N REGISTER — (16/17/20/21) PRESCALER OPERATING IN FRACTIONAL MODE
5.2.3 FRACTIONAL MODULUS ACCUMULATOR (FRAC_CNTR)
Divide
Divide
24–39
16383
48–79
32767
Ratio
Ratio
1–23
1–47
40
41
80
81
...
...
Modulus 15
14/15
1/15
2/15
N/A
0
•
Fractional Ratio (F)
0
0
1
0
0
1
.
.
0
0
1
0
0
1
.
.
Modulus 16
0
0
1
0
0
1
.
.
14/16
15/16
1/16
2/16
0
•
Divide Ratios Less than 24 are impossible since it is required that C
Divide Ratios Less than 48 are impossible since it is required that C
0
0
1
0
0
1
Some of these N values are Legal Divide Ratios, some are not
.
Some of these N values are Legal Divide Ratios, some are not
.
0
0
1
0
0
1
.
.
(Continued)
C Word
C Word
RF_N[5]
0
0
1
0
0
1
.
.
0
0
0
1
1
•
RF_N_CNTR [14:0]
RF_N_CNTR [14:0]
0
0
1
0
0
1
.
.
18
0
0
1
0
0
1
.
.
RF_N[4]
0
0
0
1
1
•
1
1
1
1
1
1
.
.
(RF_N[2]–RF_N[5])
FRAC_CNTR
0
0
1
0
0
1
.
.
RF_N[3]
1
1
1
1
1
1
.
.
(RF_N[6]–RF_N[20])
0
0
1
1
1
•
(RF_N[6]–RF_N[20])
0
0
0
0
0
0
0
1
B Word
B Word
>
>
=3
=3
0
0
1
0
0
1
.
.
RF_N[2]
0
0
1
0
0
1
.
.
A Word
A Word
0
1
0
0
1
•
0
1
1
0
1
1
.
.