LMX2595EVM: can not be locked

Hi Jinjing,

First of all, check the USB2ANY communication.

- set POWERDOWN = 1, did you see a current drop? What is the current?

- set POWERDOWN = 0, what is the current?

- Did you check the CE pin in TICS Pro to enable the device?

Hi Noel Fung,

-Connection Mode: USB2ANY

-set POWERDOWN = 1  Current:0.08A

-set POWERDOWN = 0  Current:0.46A

-CE_TP on board:3.22V

Hi Jinjing,

Ok, the USB2ANY seems working.

Try one more time:

- Vcc power up the EVM

- ensure you get signal from the on-board 100MHz XO

- in TICS Pro, click Default configuration and select Default Mode 20xx-xx-xx

- In User Controls page, ensure the CE box (in the bottom of the User Controls page) is checked

- At the top of the User Controls page, check the RESET box and then uncheck the box (to reset and then release reset)

- click USB communications and select Write All Registers

 You should be able to get 7GHz signal from RFoutA and the LED should lit.

Let us know if you still has problem with the EVM

Hi Noel Fung,

-power up the EVM，current：0.22A

-the signal form the on-board 100 XO should be ok

 the 100M signal before C14（Capacitance） shown below：

the 100M signal behind C14（Capacitance）shown below：

-CE box is checked

-finally the led is not light，and the 7GHz signal shown below：

Hi Noel Fung,

Please give me a hand!

I do not know what should I do now.

Is it possible that the EVM was damaged？

Hi Jinjing,

Looks like the usb connection is fine, you can command the device to lock to 7GHz but for some reasons, it is not able to lock to the exact frequency.

now if you program R0 one more time, will it lock?

If it is still fail, I would like to check the reference clock path. 

1. shot me a photo around the on-board XO. I want to check if there is manufacturing issue.

2. try to use an external reference clock. EVM user's guide has the details of how to do the modification.

Hi Noel Fung,

I tried some more operation：

-set the RFoutA to 1G, the signal shown as below:

-set the RFoutA to 2G, the signal shown as below:

It's still unlocked!!!

1.pothos around the on-board XO:

2.I hope Mouser electronics replace me with a new product. If I change the resistances to use external reference clock, My request may be rejected. So can you certify that this EVM is damaged?

Hi Jinjing,

Program 1GHz, but got 1.74GHz.

Program 2GHz, but got 3.48GHz. 

Looks to me that you did not calibrate the VCO after programming it to a new frequency.

After programming it to 1GHz, did you write all the registers? if not, in the menu bar, click USB communications and then Write All Registers. Could you try and get back what did you get?

BTW, the board looks good.

Hi Noel Fung,

This time,

-program 1G,but got 1.437G. (different from last time)

-program 2G,but got 2.874G.(different from last time)

-Everytime I change the frequency , I checked  the FCAL_EN box -> unchecked the box, and Write All Registers.

Hi Jinjing,

FCAL_EN must be equal to 1 in order to enable VCO calibration.

Suggest keep FCAL_EN=1 all the time. Every time you change the frequency, simply write all registers.

Hi Noel Fung,

Today,

-program 1G,but got 1.328G. (different from last time)

-program 2G,but got 2.657G.(different from last time)

I keep FCAL_EN=1 all the time, Every time I change the frequency, and then Write all registers.

BTW, TICS Pro shown that FCAL_EN should be toggled to lock VCO after changing frequency.

Hi Noel Fung,

What should I do now?

Hi Jinjing,

One last request to you, would you please measure the Vtune voltage at the Vtune_TP and at C4_LF?

Hi Noel Fung,

There must be something wrong, both of the voltages at the Vtune_TP and C4_LF is Zero.

Hi Noel Fung,

Thanks a lot！