Programming Description (Continued)
R1 REGISTER
The R1 register address bits (R1 [1:0]) are “01”.
The IF_FREQ bits selects the default IF frequency applicable to the specific CDMA system. For the LMX2522 the default IF
frequency is 440.76 MHz, and for the LMX2532 the default IF frequencies are 367.20 MHz and 170.76 MHz, depending on
variant.
Reference Frequency Selection bit (OSC_FREQ) selects either 19.20 MHz or 19.68 MHz for the reference oscillator frequency.
The internal spurious reduction scheme is controlled by the SPUR_RDT [1:0] bits. There are two different spur reduction
schemes: a continuous tracking mode and a single optimization mode. The continuous tracking mode will adjust for variations in
voltage and temperature. The single optimization mode fixes the internal compensation parameters only when the PLL goes into
the locked state. The spur reduction can also be disabled, but it is recommended that the continuous mode be used for normal
operation.
The OB_CRL [1:0] bits determine the power level of the RF output buffer. The power level is set according to the system
requirement.
The two bits, RF_EN and IF_EN, logically select the active state of the RF/GPS synthesizer system and the IF PLL, respectively.
The entire IC can be placed in a power down state by using the CE control pin (pin 20).
R1 REGISTER
Register
MSB
SHIFT REGISTER BIT LOCATION
LSB
23
22 21
20 19 18 17 16 15 14 13 12
11
10 98765
4
3
2
1
0
Data Field
Address
Field
R1
(Default)
IF_
FREQ
[1:0]
OSC_
FREQ
10000000
SPUR_
RDT
[1:0]
0
0101OB_
CRL
[1:0]
RF_
EN
IF_
EN
01
Name
Functions
IF_FREQ [1:0]
IF Frequency Selection
00 = 170.76 MHz (LMX2532LQ0967)
01 = 367.20 MHz (LMX2532LQ1065)
10 = 440.76 MHz (LMX2522LQ1635)
OSC_FREQ
Reference Frequency Selection
0 = 19.20 MHz
1 = 19.68 MHz
SPUR_RDT [1:0]
Spur Reduction Scheme
00 = No spur reduction
01 = Not Used
10 = Continuous tracking of variation (Recommended)
11 = One time optimization
OB_CRL [1:0]
RF Output Power Control
00 = Minimum Output Power
01 =
10 =
11 = Maximum Output Power
RF_EN
RF Enable
0=RFOff
1=RFOn
IF_EN
IF Enable
0=IFOff
1=IFOn
LMX2522/LMX2532
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13
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