LMX2595EVM: Lock Status problem

Doohwan Kim

Prodigy 70 points

Part Number: LMX2595EVM
Other Parts Discussed in Thread: LMX2595

I am having problem with Lock voltage.

For example, when I loaded 12GHz reg datas, I can see the lock status via spectrum analyzer.

But Mux out voltage is 0 V. Normally Lock status indicate high voltage in case other pll chip .

I don,t know what is wrong. Test environment is TICS Pro.

Please help me.

Doohwan, Kim

over 6 years ago

0 Hao Z over 6 years ago

TI__Mastermind 18070 points

Hi Kim,

Please check if "MUXOUT_LD_SEL" is set to "lock detect". There are two modes for this register, "lock detect" returns all 1s when the PLL is locked. "Readback" reads back registers. For details, please refer to datasheet.

Do you have a TI EVM board for LMX2595? On the EVM board, there is a green LED connected to MUXout pin. When "lock detect" is selected, the green light is turned on when the PLL is locked.

Regards,

Hao

0 Doohwan Kim over 6 years ago in reply to Hao Z

Prodigy 70 points

All setting status is same as upper picture. Lock Voltage is still 0V after reseting and loading. But Spectrum analyzer shows good locking status . 1 pin of Dip Sw status is off. 2 pin of Dip Sw status is on.

0 Hao Z over 6 years ago in reply to Doohwan Kim

TI__Mastermind 18070 points

Hi Kim,

Can you change that register to "readback" and see if you are able to read back lock status?

Regards,
Hao

0 Hao Z over 6 years ago in reply to Hao Z

TI__Mastermind 18070 points

By the way, did you toggle the "FCAL_EN" after changing frequency in the GUI?

Regards,
Hao

0 Doohwan Kim over 6 years ago in reply to Hao Z

Prodigy 70 points

Dear Hao

I toggled the "FCAL_EN" after changing frequency in the GUI. But the result is same.

0 Hao Z over 6 years ago in reply to Doohwan Kim

TI__Mastermind 18070 points

Hi Kim,

Do you have a TI EVM? If so, can you hook up the EVM, go to Ticspro -> "Default configuration" (on the tool bar) and load the latest default setting, toggle FCAL_EN and see if the green LED on the board is on?

If not, please do the same (load default, toggle FCAL_EN and see if MUXout pin is 1), but it'll be much more difficult to debug if it is not working.

Regards,
Hao

0 Hao Z over 6 years ago in reply to Hao Z

TI__Mastermind 18070 points

Also, I recall that you mentioned in another post that the current was not right. Does that apply to this post? Can you at least communicate to the part? The current should be a little below 400mA and above 350mA when it operates correctly under default settings.

Regards,
Hao

0 Doohwan Kim over 6 years ago in reply to Hao Z

Prodigy 70 points

Dear Hao
Green LED After Default configuration, and I changed frequency, LED Lock shows normal.
Can you explain this situation? Loading Data problem?

Regards

Doohwan, Kim

0 Doohwan Kim over 6 years ago in reply to Hao Z

Prodigy 70 points

I found problem. DC/DC converter noise makes unlock status and low current.

0 Hao Z over 6 years ago in reply to Doohwan Kim

TI__Mastermind 18070 points

Hi Kim,

There's probably something wrong with your previous setting. You can compare your previous register values (with which the device fails to lock) with current values (with which the device locks) and see what's different.

To do so, you can go to Ticspro -> file -> Export hex register values. You can then compare those register values in excel or any other tool that you prefer.

Regards,
Hao

0 Doohwan Kim over 6 years ago in reply to Hao Z

Prodigy 70 points

Thanks
Regards,

Doohwan, Kim

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LMX2595EVM: Lock Status problem