LMX2310U National Semiconductor Corporation, LMX2310U Datasheet - Page 26

• Manufacturer Part Number: LMX2310U
• Description: Pllatinum? Ultra Low Power Frequency Synthesizer For Rf Personal Communicationscommunications
• Manufacturer: National Semiconductor Corporation

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Control Bit Register Location
Register Most Significant Bit
Control Bit
Divider Value
PD_POL
CPo_TRI
3.0 Programming Description
3.2 R REGISTER
The R register contains the R_CNTR control word and PD_POL, CPo_4X, CP_TRI, FoLD0, FoLD1 control bits. The detailed
descriptions and programming information for each control word is discussed in the following sections.
3.2.1 R_CNTR[14:0]
The reference divider can be programmed to support divide ratios from 2 to 32,767. Divide ratios of less than 2 are prohibited.
3.2.2 PD_POL
The PD_POL control bit is used to set the polarity of the phase detector based on the VCO tuning characteristic.
3.2.3 CPo_4X
The CPo_4X control bit allows the charge pump output current magnitude to be switched from 1 mA to 4 mA. This happens
asynchronously or immediately with the change in CPo_4X bit.
3.2.4 CPo_TRI
The CPo_TRI control bit allows the charge pump to be switched between a normal operating mode and a high impedance output
state. This happens asynchronously or immediately with the change in CPo_TRI bit.
Control Bit
R
32,767
CPo_4X
2
3
•
FoLD1
21
Register Location
R[17]
0
0
1
•
FoLD0
Charge Pump Output Current
Phase Detector Polarity
Charge Pump TRI-STATE
R[19]
20
Register Location
Reference Divider (R COUNTER)
0
0
1
•
R[18]
CP
TRI
19
O
Phase Detector Polarity Negative VCO Tuning Characteristic Positive VCO Tuning Characteristic
_
0
0
1
•
Charge Pump TRI-STATE
CP
Description
4X
18
O
_
0
0
1
•
Description
POL
PD_
17
SHIFT REGISTER BIT LOCATION
Charge Pump Output Current Magnitude
0
0
1
•
R[17]
R[19]
16
(Continued)
VCO Characteristics
R[18]
0
0
1
•
15
Data Field
Description
14
26
0
0
1
•
Charge Pump Operates Normal
R_CNTR[14:0]
R[16:2]
13
0
0
1
•
12
0
R_CNTR[14:0]
11
0
0
1
•
0
20043809
10
0
0
1
•
9
Function
8
Function
0
0
1
•
7
1X Current
Charge Pump Output in High
6
0
Least Significant Bit
0
0
1
•
5
Impedance State
Function
4
0
0
1
•
1
3
1
2
4X Current
1
1
1
•
Address
1
1
0
Field
0
1
1
•
0
0