LMX2335 National Semiconductor, LMX2335 Datasheet - Page 10

• Manufacturer Part Number: LMX2335
• Description: PLLatinum Dual Frequency Synthesizer for RF Personal Communications
• Manufacturer: National Semiconductor

www.national.com
Functional Description
Note 5: The I
Note 6: Activation of the RF2 PLL or RF1 PLL powerdown modes result in the disabling of the respective N counter divider and debiasing of its respective f
(to a high impedance state). The powerdown function is gated by the charge pump to prevent unwanted frequency jumps. Once the powerdown program mode is
loaded, the part will go into powerdown mode when the charge pump reaches a TRI-STATE condition. The R counter and Oscillator functionality does not become
disabled until both RF2 and RF1 powerdown bits are activated. The OSC
dition exists. The MICROWIRE control register remains active and capable of loading and latching data during all of the powerdown modes.
Note 7: PHASE DETECTOR POLARITY
Depending upon VCO characteristics, the R16 bits should be set accordingly:
When VCO characteristics are positive like (1), R16 should be set HIGH;
When VCO characteristics are negative like (2), R16 should be set LOW.
Note 8:
CP o
X — don’t care condition
0
1
RF1 R[19]
(RF1 LD)
LOW current state = 1/4 x I
Phase Detector Polarity
0
0
1
1
X
X
X
X
0
0
1
1
C1
0
0
Negative
(Note 7)
Positive
C2
0
1
RF2 R[19]
(RF2 LD)
0
1
0
1
0
0
1
1
0
1
0
1
Detector Polarity
Detector Polarity
CP o
C1
RF2 Phase
RF1 Phase
1
1
(Continued)
HIGH current.
R16
TABLE 3. The F
TABLE 2. Mode Select Truth Table
RF1 R[20]
TABLE 1. Programmable Modes
(RF1 F
Normal Operation
D
0
0
0
0
0
1
0
1
1
1
1
1
C2
TRI-STATE
o
0
1
TRI-STATE
VCO Characteristics
o
)
in
RF1 I
is connected to V
RF2 I
o
LD Output Truth Table
R17
RF2 R[20]
10
(RF2 F
Prescaler
Prescaler
CP O
CP o
RF2
RF1
0
0
0
0
1
0
1
0
1
1
1
1
N19
(Note 5)
o
HIGH
LOW
I
)
CP o
TRI-STATE
TRI-STATE
CC
DS012332-7
RF2 D
RF1 D
through 100 k resistor and the OSC
R18
Disabled (Note 9)
RF2 Lock Detect (Note 10)
RF1 Lock Detect (Note 10)
RF1/RF2 Lock Detect (Note 10)
RF2 Reference Divider Output
RF1 Reference Divider Output
RF2 Programmable Divider Output
RF1 Programmable Divider Output
Fastlock (Note 11)
For Internal use only
For Internal use only
Counter Reset (Note 12)
Prescaler
o
o
128/129
64/65
RF1
Pwdn
Pwdn
RF2
RF1
N20
RF2 LD
RF1 LD
Output State
R19
F
Prescaler
o
128/129
LD
64/65
RF2
RF2 F
RF1 F
R20
out
o
o
goes HIGH when this con-
(Note 6)
pwrd up
pwrd dn
Pwdn
IN
inputs