LMX2433 datasheet(39/53 Pages) TI1

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LMX2430, LMX2433, LMX2434

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SNAS187D – FEBRUARY 2003 – REVISED JANUARY 2016

9.6.6.1 IF_TOC[0:11] - IF Synthesizer Time-Out Counter (R5[14:3])

The OSCout/ FLoutIF pin can be configured as a general-purpose CMOS tri-state output or as a fastlock output

by programming the IF_TOC appropriately. When the IF_TOC is programmed from 0 to 3, automatic fastlock is

disabled, and the OSCout/ FLoutIF pin is configured as a general-purpose CMOS tri-state output or manual

fastlock is enabled. When the IF_TOC is programmed to 0, the OSCout/ FLoutIF pin is in tri-state (high

impedance) mode. The charge-pump current is then the value specified by IF_CPG (R3[19]). When the IF_TOC

is programmed to 1, the OSCout/ FLoutIF pin is pulled to a LOW state. The charge-pump current is then set to a

HIGH gain state (IF_CPG bit = 1). This condition is known as the manual fastlock. When the IF_TOC is

programmed to 2, the OSCout/ FLout_IF pin is again pulled to a LOW state, but this time the charge-pump

current is the value specified by IF_CPG (R3[19]). When the IF_TOC is programmed to 3, the OSCout/ FLoutIF

pin is pulled to a HIGH state. Again, the charge-pump current is the value specified by IF_CPG (R3[19]). When

the IF_TOC is programmed from 4 to 4095, fastlock is enabled, and the OSCout/ FLoutIF pin is pulled to a LOW

state. Fastlock timeouts after the specified number of PFD events. At this time, the OSCout/ FLoutIF pin switches

to tri-state (high impedance) mode. The value programmed into IF_TOC represents the number of PFD events

that the IF synthesizer spends in the fastlock state.

NOTE

Any write to the IF_TOC requires a PFD event on the IF synthesizer to latch the contents.

This means that writes to the IF_TOC take effect synchronously with the next PFD event.

Table 39. IF PLL Fastlock Time-Out Counter

FASTLOCK PERIOD

OSCout/ FLoutIF PIN

IF_TOC[11:0]

FASTLOCK MODE

ICPoutIF MAGNITUDE

[PFD Events]

FUNCTIONALITY / STATE

Disabled

N/A

General-Purpose.

ICPoutIF magnitude

High Impedance State

controlled by R3[19]

Enabled

N/A

General-Purpose.

ICPoutIF = 4 mA

Manual Fastlock

Logic LOW State

Disabled

N/A

General-Purpose.

ICPoutIF magnitude

Logic LOW State

controlled by R3[19]

Disabled

N/A

General-Purpose.

ICPoutIF magnitude

Logic HIGH State

controlled by R3[19]

Enabled

FastLock.

ICPoutIF = 4 mA

Automatic Fastlock

Logic LOW State. Switches

Switches to 1 mA after 4

to High Impedance after 4

PFD events

…

4095

Enabled

4095

FastLock.

ICPoutIF = 4 mA

Automatic Fastlock

Logic LOW State. Switches

Switches to 1 mA after

to High Impedance after

4095 PFD events

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