lmx2525 National Semiconductor Corporation, lmx2525 Datasheet - Page 10

• Manufacturer Part Number: lmx2525
• Description: Pllatinum Dual Frequency Synthesizer System With Integrated Vcos
• Manufacturer: National Semiconductor Corporation

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Functional Description
BAND SELECT MODE
The BS pin and BS bit can be used to select one of the two
RF VCO outputs. When using the BS pin, the BS bit must be
set to 0, and when using the BS bit, the BS pin must be tied
to ground. When using the BS pin, the state of the input must
exceed the minimum band select set up time prior to the LE
signal transition. The truth table summarizing the band select
logic is as follows:
LOCK DETECT MODE
The LD output can be used to indicate the lock status of the
PLL. Bit 6 in Register R1 determines the signal that appears
Note 15: LD output becomes LOW when the phase error is larger than t
Note 16: LD output becomes HIGH when the phase error is less than t
four or more consecutive cycles.
Note 17: Phase Error is determined on the leading edge. Only errors greater
than t
W1
BS Pin
HIGH
LOW
LOW
and t
W2
TABLE 2. Band Select Modes
are labeled.
FIGURE 2. Lock Detect Timing Diagram Waveform (Notes 15, 16, 17, 18, 19)
BS Bit
0
0
1
(Continued)
PDC1500
PDC1500
PDC800
Mode
W1
W2
for
.
10
on the LD pin. When the PLL is not locked, the LD pin
remains LOW. After obtaining phase lock, the LD pin will
have a logical HIGH level. The LD output is always LOW
when the LD register bit is 0 and in power down mode.
Note 18: t
both bands.
Note 19: The lock detect comparison occurs with every 64
f
N
.
RF PLL Section
W1
LD Bit
Not Locked
is 5 ns for PDC1500 and 10 ns for PDC800. t
0
1
Locked
TABLE 3. Lock Detect Modes
TABLE 4. Lock Detect Logic
Disable (GND)
Enable
Mode
LD Output
HIGH
LOW
20068908
th
W2
cycle of f
is 10 ns for
R
and