LMX2592: LMX2592 for the lock time question

Mickey Zhang

Genius 12080 points

Part Number: LMX2592

Hi team,

The customer is using LMX2592. He uses the external 25MHZ as the reference input. The frequency switching time is 15ms.

For the customer's application, can be the lock time be reduced to less than 50us?

How to determine the lock time?

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

over 7 years ago

0 Mickey Zhang over 7 years ago

TI__Genius 12080 points

Hi team,

Can anyone support this case? The customer is waiting for my reply.

0 Noel Fung over 7 years ago in reply to Mickey Zhang

TI__Guru** 107030 points

Hi Mickey,

Datasheet section 8.1.8 has some suggestions on speeding up the lock time.
In addition, use higher reference input clock frequency helps shortening the lock time.

0 Mickey Zhang over 7 years ago in reply to Noel Fung

TI__Genius 12080 points

Hi Noel,

For the customer's application, 25MHZ is used as the reference input. Can the lock time be less than 50us?

What is the input reference clock frequency when the lock time can be less than 50us?
Would you explain more about this?

0 Brian Wang over 7 years ago in reply to Mickey Zhang

TI__Expert 8485 points

Mickey,

If you see the section Noel pointed, the calibration speed is related to the calibration clock. The fastest speeds we achieve is about 25us, and is with a calibration clock of 200MHz. Roughly, the fastest calibration speed changes with the factor of the calibration clock, so about 50us (with calibration clock=100 MHz), about 100us (with calibration clock=50 MHz), about 200us (with calibration clock=25 MHz). Hope this is clear.

Clock & timing

Clock & timing forum

LMX2592: LMX2592 for the lock time question