Datasheet

L M K 0 4 1 X X - R E V 3 E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S

SNLU099

o EN_PLL2_XTAL – Enables Crystal mode for PLL2. For use with Crystals as

opposed to a VCXO.

o EN_PLL2_REF2X – Doubles the reference frequency of PLL2. Note with this is

enabled, the PLL_R value is invalid. Program the Reference Oscillator on PLL2

Tab to be twice the VCO frequency on PLL1 tab. This adjustment must be done

manually.

CLKin Options Box

o CLKin_SEL – Sets manual or automatic switching modes for selecting a

reference oscillator for PLL1.

o LOS_TIMEOUT – The timeout value before a loss of signal on a clock input is

registered on the LOS pins.

o LOS_TYPE – Set the type of output for the LOS pins.

o CLKin0_BUFTYPE & CLKin1_BUFTYPE – Select the input buffer used for the

respective clock input.

PLL2_LF Box

o Set the integrated loop filter values for PLL2 including,

 PLL2_R3_LF – R3 value

 PLL2_R4_LF – R4 value

 PLL2_C3_C4_LF – C3 and C4 value at the same time

o It is also possible to set these values by clicking on the loop filter values on the

Clock Outputs tab.

CLKout Options Box

o EN_CLKout_Global – A global enable for clocks, if unchecked no outputs will

be observed!

o EN_CLKout0 through EN_CLKout4 – Individual clock output enables. These

can also be set on the Clock Outputs tab.

o The number of options vary depending on the option of the LMK device selected.

 CLKout#_PECL_LVL – Set the level of an LVPECL output to LVPECL

or 2VPECL. The 2VPECL a higher output level than LVPECL.

CLKout CMOS Options Box

o The presence of this box and the number of options on this tab depends upon the

option of the LMK device.

 CLKout##_STATE – Set the state of the individual LVCMOS output.

VCO Control – FC Box

o OSCin_FREQ – Must be set to the reference frequency of PLL2 in MHz, which

should normally be the VCO frequency of PLL1. NOTE: It is important to

enter the correct frequency value in this field, as it is used by the internal

state machine of the LMK041xx to execute its calibration routine for the

internal VCO. An incorrect value may result in an unlocked condition for the

synthesizer.

 Entering a reference oscillator frequency on PLL2 tab will automatically

update this register with the frequency to the nearest MHz.

Program Pins Box

o GOE – Set high or low voltage on GOE pin. Checked is high voltage.

 If GOE is low, then no clock outputs will be observed!