Changing the sampling frequency of TSW1266

AnthonyZ

In the datasheet, the sampling frequency is 614.4MHz, which is almost fixed.

When I try to tune the parameters of the PLL in the LMK4800 Main of the GUI, I don't know how my sampling frequency after tone

Is that any straight forward way to change the sampling frequency of TSW1266 without using the external clock?

for example, My required sampling frequency is 600MHz

Best

Anthony

over 9 years ago

0 Richard Prentice over 9 years ago

TI__Mastermind 29220 points

Hi,

The TSW1266 has a VCXO of 122.88MHz installed on board, and the 614.4MHz clock is generated from the VCXO as 5 x 122.88 = 614.4MHz.

There are several options. One would be to solder a different VCXO into position Y4 on the board, such as a 120MHz VCXO and then nothing else on the EVM would have to change. But a simpler option would be to bring in your desired clock on SMA J8 CLKIN1, and then use the LMK clock device in clock distribution mode. In this mode, the LMK uses the clock from J8 directly, instead of using one of the LMK internal VCOs. This would require a little different programming for the LMK.

Regards,

Richard P.

0 AnthonyZ over 9 years ago in reply to Richard Prentice

Prodigy 200 points

Hi Richard,

Thank you for your quick reply

I found that a 100MHz crystal is also available after I check the part number of Y4, which is a CRYSTEK CVHD-950 series crystals at different frequency.

It is more convenience if I can use 100MHz crystal, how can I change the PLL (divide by N setting) in order to achieve the 200, 300, 400, 500 or 600MHz?

Best

Anthony