LMX2492 EVM

Hongrun Li

Prodigy 90 points

Other Parts Discussed in Thread: LMX2492, USB2ANY

Hi all!

LMX2492 EVM can generate a signal like this

and my configuration is like this

this signal only have 4sections,if I want to generate a signal like this but have 8 sections,how should I configue???

Thanks!!

over 8 years ago

0 Timothy T over 8 years ago

TI__Mastermind 28560 points

Hello, thanks for your inquiry, I've notified an engineer to respond.

0 Simon Damphousse over 8 years ago

TI__Expert 5370 points

Dear Mr. Li,

thank you for your question.

The maximum number of state for the ramping feature 8 [0-7]. you have indeed use them all for the wave you are showing so using this method will not allow you to do more than 4 sections.

However, it appears you are trying to do FSK modulation on top of the ramp. you can use the FSK feature AND the ramp at the same time. Enable a single ramp and the FSK such as in this example:

You will get this sort of modulation and you can easily "sync" the FSK with the ramping as well...

Regards, Simon.

0 Simon Damphousse over 8 years ago in reply to Simon Damphousse

TI__Expert 5370 points

Dear Mr. Li, I placed images there? Are you able to see them? regards, Simon.

0 Simon Damphousse over 8 years ago in reply to Simon Damphousse

TI__Expert 5370 points

fsk_plus_ramp.docx

0 Hongrun Li over 8 years ago in reply to Simon Damphousse

Prodigy 90 points

Hi Simon!
Thank you for your reply!
I have seen the file,and got the way how to do this.I have two questions,first,when should I give the terminal MOD rising edge,and how?external trigger?second,the parameter FSK deviation is equal to the 2's complement of the Fpd*FSK_DEV/2.^24,is it right?and what is your specific value of Fpd and FSK_DEV?

Thanks!
Li

0 Simon Damphousse over 8 years ago in reply to Hongrun Li

TI__Expert 5370 points

Dear Mr LI,

yes, MOD pin need to set as a input and will work with CMOS signal.

Fpd is the phase detector frequency for your use case. FSK_DEV is the desired offset you are trying to get on your ramp.

Regards, Simon.

0 Hongrun Li over 8 years ago in reply to Simon Damphousse

Prodigy 90 points

Hi Simon!
OK，Thank you for your reply!
So, I have to set MOD_PIN as input and set MOD_MUX as input MOD?But I still have questions,first,the MOD pin on the 2492EVM is connected to PC through USB2ANY,what should I do to generate a rising edge?second,do you mean that I have to generate rising edge at set intervals?
Thanks!
Li

Clock & timing

Clock & timing forum

LMX2492 EVM