LMX2332U Datasheet, PDF (36/42 Pages) National Semiconductor (TI) – PLLatinum Ultra Low Power Dual Frequency Synthesizer for RF Personal Communications

2.0 Programming Description (Continued)
2.4.4 TRI-STATE ID_o IF
IF SYNTHESIZER CHARGE PUMP TRI-STATE CURRENT
IF R[19]
The TRI-STATE ID_o IF bit allows the charge pump to be switched between a normal operating mode and a high impedance output
state. This happens asynchronously with the change in the TRI-STATE ID_o IF bit.
Furthermore, the TRI-STATE ID_o IF bit operates in conjuction with the PWDN IF bit to set a synchronous or an asynchronous
powerdown mode.
Control Bit
TRI-STATE ID_o IF
Register Location
IF R[19]
Description
IF Charge Pump
TRI-STATE Current
Function
0
1
IF Charge Pump
IF Charge Pump
Normal Operation
Output in High
Impedance State
2.5 RF R REGISTER
The RF R register contains the RF R_CNTR, PD_POL RF, ID_o RF, and TRI-STATE ID_o RF control words, in addition to two bits
that compose the F_oLD control word. The detailed descriptions and programming information for each control word is discussed
in the following sections.
Reg. Most Significant Bit
SHIFT REGISTER BIT LOCATION
Least Significant Bit
21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Data Field
Address
Field
RF
TRI-
R
STATE IDo
FoLD1 FoLD3
IDo RF
RF
PD_
POL
RF
RF R_CNTR[14:0]
01
2.5.1 RF R_CNTR[14:0] RF SYNTHESIZER PROGRAMMABLE REFERENCE DIVIDER (R COUNTER) RF R[2:16]
The RF reference divider (RF R_CNTR) can be programmed to support divide ratios from 3 to 32767. Divide ratios less than 3
are prohibited.
Divide Ratio
3
4
•
32767
RF R_CNTR[14:0]
14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2.5.2 PD_POL RF
RF SYNTHESIZER PHASE DETECTOR POLARITY
RF R[17]
The PD_POL RF bit is used to control the RF synthesizer’s phase detector polarity based on the VCO tuning characteristics.
Control Bit
PD_POL RF
Register Location
RF R[17]
Description
RF Phase Detector
Polarity
Function
0
1
RF VCO Negative
RF VCO Positive
Tuning
Tuning
Characteristics
Characteristics
RF VCO Characteristics
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