LMX2433 datasheet(36/53 Pages) TI1

36 / 53 page

LMX2430, LMX2433, LMX2434

SNAS187D – FEBRUARY 2003 – REVISED JANUARY 2016

www.ti.com

9.6.4.2.1

IF_R[14:0] - IF Synthesizer Programmable Reference Divider (R Counter) (R3[17:3])

The IF reference divider (IF_R) can be programmed to support divide ratios from 3 to 32,767. Divide ratios less

than 3 are prohibited.

Table 28. IF R Divider

IF_R[14:0]

DIVIDE RATIO

•

32767

9.6.4.2.2

IF_CPP - IF Synthesizer Phase Detector Polarity (R3[18])

The IF_CPP bit is used to control the PFD polarity of the IF synthesizer based on the VCO tuning characteristics.

Table 29. IF PLL Charge-Pump Polarity

FUNCTION

CONTROL BIT

DESCRIPTION

IF_CPP

R3[18]

IF PFD Polarity

IF VCO Negative Tuning

IF VCO Positive Tuning

Characteristics

Figure 32. IF VCO Characteristics

9.6.4.2.3

IF_CPG - IF Synthesizer Charge-Pump Current Gain (R3[19])

The IF_CPG bit controls the charge-pump gain of the IF synthesizer. Two gain levels are available.

Table 30. IF PLL Phase Detector Polarity Bit

FUNCTION

CONTROL BIT

DESCRIPTION

IF Charge-Pump Current

LOW

HIGH

IF_CPG

R3[19]

Gain

1 mA

4 mA

9.6.4.2.4

IF_CPT - IF Synthesizer Charge-Pump Tri-State (R3[20])

The IF_CPT bit allows the charge pump to be switched between a normal operating mode and a high impedance

output state. This happens asynchronously with the change in the IF_CPT bit.

Furthermore, the IF_CPT bit operates in conjuction with the IF_PD bit to set a synchronous or an asynchronous

power-down mode. Refer to IF_PD - IF Synthesizer Power Down (R4[23]) for more details on how to program

the IF_PD bit.

Table 31. IF PLL Charge-Pump Polarity Bit

FUNCTION

CONTROL BIT

DESCRIPTION

IF_CPT

R3[20]

IF Charge-Pump Tri-State

IF Charge Pump Normal

IF Charge-Pump Output in

Operation

High Impedance State

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