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FMC150 using external clock

I have tried many different values to config CDCE72010's register, but i failed. I just want an external clock(119MHz)  to be the ads62p49's sampling clock. After i config the CDCE72010,  I do get a pair of 119MHz signal in out2_p and out2_n( which are to feed the ads[font=Verdana][size=78%]62p49's sampling clock).  But i don't think they are LVPECL signal , because out2_p and out2_n have the same wave, but their amplitude are different, out2_n's amplitude is 4 times out2_p's.  [/size][/font]

I found in the forum someone have the same problem(about how to config CDCE72010), and 4DSP's engineer's advise is to refer to the 'reference software application' . however after i download the 1GB-size 4FM.SDK file and setup on my computer,  I am more confused about how to operator this application( i cannot find  the CDCE72010's register setting)

Anyway, all i want to know are some points on configing the CDCE72010.( I have read the datasheet many times,  some points are really not explained clearly)

1. when i use external clock, I use the CDCE72010's  AUX as the feed of  output divider.  Should  the AUX be congfiged as LVPECL or LVDS ? 

2. How to config register8's  8.2 to 8.5  ( i think these bits are very importent,and  their value is decided by the chip's  [/size][size=78%][color=rgb(53, 161, 212)][/color][/size][size=78%][font=Verdana][/size][size=78%]  the FMC150 data manul oughts to  tell us how to config them) [/size][/font]

3. Should the output9  be disabled?

4.Do the PRI_REF and SEC_REF's  setting  not have any effect  in case i use external clock.

Help me !


Dear Cecilia,

You can still get in touch with TI for question around the CDCE chip. The CDCE72010 register setting in the software application are found in the following module:


The software application's main in main.cpp take an argument for clock mode. There are three clock modes: 0 = Internal clock with internal reference, 1 = External clock and 2= Internal Clock with external reference. The value passed as argument i converted to integer and placed in modeClock variable. modeClock is then passed to fmc15x_init() which will call fmc15x_clocktree_init().

There is also some important information in the FMC150 user manual on how to control the device.

I hope that helps!

Best Regards,

Dear Arnaud,

Thanks for your reply.  [font=verdana]I found the CDCE72010's register setting  in  software application w[/font][font=verdana]ith your help[/font].  I finally observe the correct LVPECL signal([font=verdana]119MHZ)[/font][font=verdana]  in out2_p and out2_n succesfully![/font]

The CDCE72010's register setting is as follows(using external clock as the ADS62P49's sampling clock)
83400002 (divider num: 1)
E9800004(divider num: 2)
83400017[font=verdana](divider num: 1)[/font]

This topic is being closed because the issue is considered as resolved by 4DSP. Feel free to create a new topic for any further inquiries.