LMX2542LQ2121 NSC [National Semiconductor], LMX2542LQ2121 Datasheet - Page 21

• Manufacturer Part Number: LMX2542LQ2121
• Description: PLLatinum Cellular and GPS Frequency Synthesizer System with Integrated VCO
• Manufacturer: NSC [National Semiconductor]

Reg
Reg
R5
R6
2.0 Programming Description
2.7 R5 REGISTER
The R5 register contains the IF_R control word. The register address bits are R5[4:0] = 01111. Register R5 is active only when
the SPI_DEF bit in Register R0 is set to 0. Regsiter R5 should only be used to set the IF R counter if the default value is not
desired. The detailed description and programming information for this control word is discussed in the following section.
2.7.1 IF_R[8:0] - IF Synthesizer Programmable Reference Divider (R5[13:5])
The IF_R control word is used to setup the IF synthesizer’s reference divider. The IF_R control word can be programmed to
values ranging from 2 to 511. Divide ratios less than 2 are prohibited.
2.8 R6 REGISTER
The R6 register is used for internal testing of the device and is not intended for customer use. The register address bits are
R6[5:0] = 011111. Register R6 is active only when the SPI_DEF bit in Register R0 is set to 0.
MSB
MSB
23
23
0
0
22
22
0
0
21
21
0
0
20
20
0
0
19
19
0
Divide Ratio
0
18
511
18
0
0
2
3
•
17
17
0
0
16
16
0
1
DATA[17:0] FIELD
DATA[18:0] FIELD
15
15
0
1
8
0
0
1
•
SHIFT REGISTER BIT LOCATION
SHIFT REGISTER BIT LOCATION
14
14
(Continued)
0
1
7
0
0
1
•
13
13
1
12
12
21
1
6
0
0
1
•
11
11
1
5
0
0
1
•
IF_R[8:0]
10
10
1
IF_R
4
0
0
1
•
[8:0]
9
9
1
3
0
0
1
8
8
1
•
7
7
1
2
0
0
1
•
6
6
1
1
1
1
1
•
5
5
0
0
0
1
1
•
4
0
4
1
ADDRESS
3
1
3
1
FIELD
ADDRESS
[5:0]
FIELD
[4:0]
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2
1
2
1
1
1
1
1
LSB
LSB
0
1
0
1