LMX2594: Looking for details of SYNC pin of LMX2594

Vinayak Chabbi

Part Number: LMX2594

Hi,

I'm looking for details of SYNC pin of LMX2594, like input type it can take, max sync input frequency etc. where shall I get it?

If any doc regarding this please share.

Regards,

Vinayak

over 5 years ago

0 Noel Fung over 5 years ago

TI__Guru* 93670 points

Hi Vinayak,

Datasheet table 28 shows how to configure the SYNC format.
Input frequency range with SYNC is shown in the electrical table on page 10.

0 Vinayak Chabbi over 5 years ago in reply to Noel Fung

Expert 1100 points

Hello Fung,
Thanks for the reply.
The datasheet doesn't have the details regarding schematics of SYNC pin . If any application note is available, it will be very helpful.

Regards,
Vinayak

0 Hao Z over 5 years ago in reply to Vinayak Chabbi

TI__Mastermind 18070 points

Hi Vinayak,

Please check out the EVM user's guide for LMX2594. It has the full schematic.

Regards,

Hao

0 Vinayak Chabbi over 5 years ago

Expert 1100 points

Hello,

For LMX2594, What is the maximum output frequency in SYNC mode?

Is it possible to program more than 7500MHz in SYNC mode? If Yes please share the details to do it.

And also looking details for hardware schematics constraints for using SYNC pin, any doc regarding this?

Regards,

Vinayak

0 Hao Z over 5 years ago in reply to Vinayak Chabbi

TI__Mastermind 18070 points

Hi Vinayak,

Please refer to datasheet section 7.3.10.4 and 7.3.14.2 for SYNC pin configurations. SYNC mode does not limit output frequency, so the max output is still 15GHz.

Please check out Figure 26 to see if you need SYNC pin at all for phase sync. (If your application falls into category 1 or 2 then SYNC pin is not needed)

Regards,
Hao

0 Vinayak Chabbi over 5 years ago in reply to Hao Z

Expert 1100 points

Hello Hao,

Thanks for the reply.

When I try to program LMX2594 in sync mode to 7833MHz, in TICs pro, FVco value goes out of limit. Can you help me on this?

And what are the hardware accommodations to use SYNC pin? Please clarify.

Regards,

Vinayak

0 Hao Z over 5 years ago in reply to Vinayak Chabbi

TI__Mastermind 18070 points

Hi Vinayak,

Could you be more specific about 'VCO goes out of limit'? When output is 7833MHz, VCO should also be 7833MHz, and no channel divider is used for channel output. If you see a box turns yellow or red, please hover your mouse over that cell and you'll see the detail. Make sure that you didn't force the OUTA_MUX to channel divider.

Another possibility is that the N divider (PLL_N) value is too low. In that case the box for N divider will turn yellow or red. You need to reduce the PFD frequency to make it go away. Please refer to the 'IncludeDivide' in Table 11.

Hardware accommodations simply means that you need an external controller/pulse generator to generate a pulse for the sync pin. Refer to section 7.3.10.1 for more details.

Regards,
Hao

0 Noel Fung over 5 years ago in reply to Hao Z

TI__Guru* 93670 points

Hi Vinayak,

FYI, some resources on SYNC operation.
www.ti.com/.../TIDA-01410
training.ti.com/.../1129244

Clock & timing

Clock & timing forum

LMX2594: Looking for details of SYNC pin of LMX2594