LMX2492EVM: What parts we need to change if we use LMX2491

Cedrick

Part Number: LMX2492EVM
Other Parts Discussed in Thread: LMX2491

Hi,

Good day. I hope everything is fine.

Our customer wants to know which parts/components they need to install/remove if they will use the LMX2492EVM to evaluate LMX2491. It seems that they need to replace the VCO (U2p) however they want to make sure that all needed parts are ready before they evaluate it.

I would appreciate your help on this. Thank you.

Regards,

Cedrick

over 5 years ago

0 Vibhu Vanjari over 5 years ago

TI__Genius 11900 points

Hello Cedrick,

Both of these parts are pin-to-pin compatible. Please refer to the schematic.

Install R5 to connect output to RFout SMA
Install R14 and C5 for power to VCO and filtering
Install 0-ohm at R4pLF to connect to loop filter (you can adjust this if you want to use 4th order loop filter and also add C4pLF)
DNP R4_LF, to disconnect LF from U2
DNP R6 to disconnect U2 from RFout SMA and avoid any noise coming in from U2
Additionally, you can DNP L4 and L5 to powerdown U2 completely.

Please also refer to https://e2e.ti.com/support/clock-and-timing/f/48/p/864377/3200428

Thanks,

Vibhu

0 Art Mecina over 5 years ago in reply to Vibhu Vanjari

TI__Genius 16655 points

Hello Vibhu,

Good day.

We just received a follow-up inquiry from the same customer on this. From the LMX2492EVM's schematic, the recommended oscillator’s frequency is 1400-1624MHz. Customer is asking if they use this oscillator, will they be able to reach 6.4GHz as LMX2491 works up to this frequency? Or, should they use another oscillator to reach 6.4Ghz?

Thanks for the confirmation.

Art

0 Vibhu Vanjari over 5 years ago in reply to Art Mecina

TI__Genius 11900 points

Hello Art,

I do not believe so, U2p isn't populated on the EVM. I believe this is where they get the 1400-1624 MHz.

The oscillator isn't necessarily a recommendation, it is more so a footprint for customers to populate their own VCOs. As different customers may be evaluating VCOs in different frequency ranges.Your customer will need to pick a footprint compatible higher frequency VCO.

Thanks,

Vibhu

0 Art Mecina over 5 years ago in reply to Vibhu Vanjari

TI__Genius 16655 points

Thanks for the immediate response Vibhu!

The customer will be using the LMX2492EVM to evaluate LMX2491 and so has to populate the U2p.

Did you mean that the customer can use an oscillator (VCO) of their preference as long as it matches the footprint?

Do you have any recommended oscillator for them to be able to reach 6.4GHz on LMX2491?

Thanks!

Art

0 Noel Fung over 5 years ago in reply to Art Mecina

TI__Guru** 108550 points

Hi Art,

The footprint of U2p is a very common VCO footprint, Cyrstek CVCO55 series VCO has a lot of frequency options. Customer should also be able to find their preference VCO with the same footprint easily from the market.

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LMX2492EVM: What parts we need to change if we use LMX2491