lmx2515 National Semiconductor Corporation, lmx2515 Datasheet - Page 13

• Manufacturer Part Number: lmx2515
• Description: Pllatinum? Frequency Synthesizer System With Integrated Vco
• Manufacturer: National Semiconductor Corporation

Programming Description
R0 REGISTER
The R0 register address bits (R0 [1:0]) are “00”.
The Rx/Tx bit selects between receive and transmit modes and, in conjunction with the RF VCO selection bit (RF_SEL), the
channel spacing to be synthesized.
The RF_PD bit selects the power down mode of the RF PLL and selected VCO.
The HS bit selects between normal and high speed locking mode.
The RF_SEL bit is set to "0" for the LMX2515LQ0701 and "1" for the LMX2515LQ1321.
The RF N counter consists of the 4-bit programmable counter (RF_B counter), the 3-bit swallow counter (RF_A counter) and the
10-bit delta sigma modulator (RF_FN counter). The equations for calculating the counter values are presented below.
R0
(Default)
Counter Name
Modulus Counter
Programmable Counter
Swallow Counter
MSB
23
RX/
TX
Name
RX/TX
RF_PD
HS
RF_SEL
RF_B [3:0]
RF_A [2:0]
RF_FN [9:0]
22
RF_
PD
21
HS 0
20 19
RF_
SEL
Symbol
RF_FN
RF_B
RF_A
18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
(Continued)
RF_B
[3:0]
SHIFT REGISTER BIT LOCATION
R0 REGISTER
Data Field
13
Functions
RX/TX Mode
0 = Rx
1 = Tx
Power Down of RF Synthesizer
0 = RF synthesizer on (Active mode)
1 = RF synthesizer powered down
Locking Mode
0 = Normal Mode
1 = High Speed Mode
RF VCO Selection
0 = LMX2515LQ0701
1 = LMX2515LQ1321
RF_B Counter
4-bit programmable counter
0 ≤ RF_B ≤ 15 for both bands
RF_A Counter
3-bit swallow counter
0 ≤ RF_A ≤ 7 for LMX2515LQ1321
0 ≤ RF_A ≤ 3 for LMX2515LQ0701
RF_FN Counter
10-bit modulus counter
0 ≤ RF_FN
Functions
RF N Divider
N = 8 x RF_B + RF_A + RF_FN/FD (LMX2515LQ1321)
N = 4 x RF_B + RF_A + RF_FN/FD (LMX2515LQ0701)
RF_A
[2:0]
<
FD See Table 6 for FD values.
RF_FN
[9:0]
Address
Field
0
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LSB
0
0