lmx2335u National Semiconductor Corporation, lmx2335u Datasheet - Page 39

• Manufacturer Part Number: lmx2335u
• Description: Pllatinum Ultra Low Power Dual Frequency Synthesizer For Rf Personal Communications
• Manufacturer: National Semiconductor Corporation

Reg. Most Significant Bit
RF2
Divide Ratio
N
Divide
Ratio
2.0 Programming Description
2.4.4 TRI-STATE ID
The TRI-STATE ID
output state. This happens asynchronously with the change in the TRI-STATE ID
Furthermore, the TRI-STATE ID
powerdown mode.
2.5 RF2 N REGISTER
The RF2 N register contains the RF2 N_CNTRA, RF2 N_CNTRB, PRE RF2, and PWDN RF2 control words. The RF2 N_CNTRA
and RF2 N_CNTRB control words are used to setup the programmable feedback divider. The detailed description and
programming information for each control word is discussed in the following sections.
2.5.1 RF2 N_CNTRA[6:0]
The RF2 N_CNTRA control word is used to setup the RF2 synthesizer’s A counter. The A counter is a 7-bit swallow counter used
in the programmable feedback divider. The RF2 N_CNTRA control word can be programmed to values ranging from 0 to 127.
2.5.2 RF2 N_CNTRB[10:0]
The RF2 N_CNTRB control word is used to setup the RF2 synthesizer’s B counter. The B counter is an 11-bit programmable
binary counter used in the programmable feedback divider. The RF2 N_CNTRB control word can be programmed to values
ranging from 3 to 2047.
2.5.3 PRE RF2
The RF2 synthesizer utilizes a selectable dual modulus prescaler.
2047
TRI-STATE ID
3
4
•
PWDN
127
RF2
Control Bit
21
Control Bit
0
1
•
PRE RF2
PRE
RF2
20
10
0
0
1
•
o
19
RF2
o
o
RF2 bit allows the charge pump to be switched between a normal operating mode and a high impedance
6
0
0
1
•
18
RF2
9
0
0
1
•
Register Location
Register Location
17
RF2 SYNTHESIZER CHARGE PUMP TRI-STATE CURRENT
RF2 SYNTHESIZER SWALLOW COUNTER (A COUNTER)
RF2 SYNTHESIZER PRESCALER SELECT
o
RF2 R[19]
RF2 N[20]
RF2 SYNTHESIZER PROGRAMMABLE BINARY COUNTER (B COUNTER)
RF2 N_CNTRB[10:0]
RF2 bit operates in conjuction with the PWDN RF2 bit to set a synchronous or an asynchronous
16
8
0
0
1
•
5
0
0
1
•
15
14
7
0
0
1
•
13
SHIFT REGISTER BIT LOCATION
(Continued)
RF2 Charge Pump
TRI-STATE Current
RF2 Prescaler Select
4
0
0
1
•
Data Field
12
Description
6
0
0
1
Description
•
RF2 N_CNTRB[10:0]
RF2 N_CNTRA[6:0]
11
39
10
5
0
0
1
•
3
0
0
1
•
9
RF2 Charge Pump
Normal Operation
64/65 Prescaler
Selected
4
0
0
1
•
8
o
RF2 bit.
7
2
0
0
1
•
RF2 N_CNTRA[6:0]
0
0
3
0
0
1
•
6
5
Function
Function
2
0
1
1
•
4
1
0
0
1
•
RF2 Charge Pump
Output in High
Impedance State
128/129 Prescaler
Selected
Least Significant Bit
3
1
1
0
1
•
RF2 R[19]
RF2 N[9:19]
RF2 N[2:8]
2
RF2 N[20]
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1
1
Address
1
0
0
0
1
1
•
Field
0
1
0
1
•
0
1