lmx2581 outputs driving lmk01801

naresh kumar2

Other Parts Discussed in Thread: LMX2581, LMK01801

HI,

In our application , LMX2581 differential sine wave outputs are used to drive LMK01801 inputs and the buffer divided ouputs of LMK01801 are used for DAC (data clock :108 Mhz & dacout 432 Mhz) clocks and ADC clock (108 Mhz) respectively.

The power levels in lmx2581 (OUTx_PWR ) are set to the value : 15 which is close to 4dbm ?? (resistive pullup) which are driving lmk01801 inputs . lmk01801 has been programmed via microwire but there are no ouputs.

Is the programmed power in lmx2581 is sufficient to drive the inputs of lmk01801 ?

plz explain what should be the outx_pwr in lmx2581 has to programmed so that the differential sine wave outputs can sufficiently drive the inputs of lmk01801 ?

over 10 years ago

0 Noel Fung over 10 years ago

TI__Guru* 88320 points

hi Kumar,

the LMX2581 output at level 15 is sufficient to drive LMK. Could you share your schematic how did you interconnect LMX and LMK devices?

0 naresh kumar2 over 10 years ago in reply to Noel Fung

Prodigy 200 points

plz find attached the schematics of lmx2581 and lmk01801 used in the design

ICG.pdf

0 Noel Fung over 10 years ago in reply to naresh kumar2

TI__Guru* 88320 points

I don't see problems with the schematic.

Did you see the LMX2581 lock and there is signal output from it?

0 naresh kumar2 over 10 years ago in reply to Noel Fung

Prodigy 200 points

Hi,

LMX2581 is locked to reference 10 MHZ , differential sine wave outputs (2592 MHZ) has been fed to LMK01801 input banks (A &B), we could see bank B outputs (divided by 24) but no outputs on bank A .

we are programming the chip LMK01801 via microwire and by setting :

SYNC1/CLKoutTYPE_2 = '1' and SYNC0/CLKoutTYPE_1 ='1';

what is the use of test/CLKoutTYPE_0 pin, is this used only during pin control mode ?

0 Noel Fung over 10 years ago in reply to naresh kumar2

TI__Guru* 88320 points

hi Kumar,

Yes, the test/CLKoutTYPE_0 pin is used only during pin control mode.

you have SYNC pin asserted, but there is no output on band A. Very likely that you did not set the SYNC_POL_INV bit. See Table 7-4 in the datasheet for the correct settings. Alternatively, you may set the SYNC pin to "0".

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lmx2581 outputs driving lmk01801