LMK04828 External VCO input from TRF3765

SOUMYA SEPHALIKA

Intellectual 430 points

Other Parts Discussed in Thread: LMK04828, TRF3765

Hi,

I need to interface TRF3765 PLL output to the LMK04828 External VCO input pin i.e. CLKin2 pin of LMK04828.

As per the datasheet recommendation LMK04828 shall support 3.1GHz input at the CLKin1 input.

But TRF3765 PLL can generate a output maximum up to 4.8GHz.

Is it possible to handle 4.8GHz input at the CLkin1 pin of LMK04828 chip ?

Regards

Soumya

over 10 years ago

0 Gabe Ayala over 10 years ago

TI__Genius 10320 points

Hi Soumya,
The LMK04828 CLKin1 input has a maximum input spec of 3.1 GHz as you noted and should not be violated for proper device functionality.
Gabe

0 SOUMYA SEPHALIKA over 10 years ago in reply to Gabe Ayala

Intellectual 430 points

Hi Gabe,

Your point is correct, But in one of the TI evaluation board the TRF3765 output has been feed to LMK04828 as external VCO input.

Reference evaluation board schematics: tidre83

0 Gabe Ayala over 10 years ago in reply to SOUMYA SEPHALIKA

TI__Genius 10320 points

Hi Soumya,
I am not familiar with the TIDA board but can you confirm the TRF3765 is operating at 4+ GHz on OutA-/OutA+? The operational limits of the TRF3765 allow for operationg up to 4.8 GHz but other frequencies are possible - I could not find documentation on the default configuration of this device.
Gabe

0 SOUMYA SEPHALIKA over 10 years ago in reply to Gabe Ayala

Intellectual 430 points

Hi Gabe,

In datasheet the VCO frequency range is not available. But two VCOs are there & it can have wide range of VCO frequencies by changing the R & N divider value.

Kindly share the VCO range of both the VCOs of the PLL.

Is there any Clock design tool available for the TRF3765 PLL ?

In the evaluation module the TRF3765 clock output is rooted to the LMK04828 External VCO input.

Is LMK04828 is able to take 4GHz at its External VCO input pin ?

Regards

Soumya
Hardware Design Engineer

0 Gabe Ayala over 10 years ago in reply to SOUMYA SEPHALIKA

TI__Genius 10320 points

Hi Soumya,

At this time the TRF3765 PLL is not in Clock Design Tool.

The LMK04828 is specified to allow External VCOs operating at a maximum of 3.1 GHz as noted in the DS.

Gabe

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LMK04828 External VCO input from TRF3765