LMK03806: SYNC pin control method

JH Shin

Part Number: LMK03806
Other Parts Discussed in Thread: LMK04806

Hello,

My customer wnats to use the sync pin of the LMK03806 to synchronize the phase of all the clock outputs.

For this, please explain in detail how to control the sync pin.

When SYNC_POL_INV is set to 1, should the sync pin input be toggled from High to Low once after the output clock has stabilized? After this, if the sync pin input is kept low, will the sync be maintained?

When the sync pin input is connected as pull-down, is it possible to synchronize even if SYNC_POL_INV is controlled from low to high?

Thank you.

over 4 years ago

0 Julian Hagedorn over 4 years ago

TI__Mastermind 20900 points

Hi JH,

see an example for sync here:

This is from the LMK04806 which has a similar sync, except that it also has DDLY.

The SYNC pin needs the rising edge (if SYNC_POL_INV=1) to assert the outputs again. If SYNC pin is kept at LOW level, then the outputs will remain off.

You can use SYNC_PLL_DLD=1 to keep the outputs disabled until the PLL locks.

regards,

Julian

0 JH Shin over 4 years ago in reply to Julian Hagedorn

Guru 11480 points

Hi Julian,

Thank you for your help.

When the sync pin is connected by pull-up or pull-down, is there any way to synchronize using only register control?

Thank you.

0 Timothy T over 4 years ago in reply to JH Shin

TI__Mastermind 28560 points

Hello JH,

You can change the SYNC_POL_INV state to cause a SYNC.

73,
Timothy

0 JH Shin over 4 years ago in reply to Timothy T

Guru 11480 points

Hello Timothy,

Thank you for your reply.

Could you please tell us more how to synchronize via the SYNC_POL_INV control?

Is it correct to change SYNC_POL_INV = 1 to 0 with pull-up connected to the SYNC pin?

Regards,

0 Timothy T over 4 years ago in reply to JH Shin

TI__Mastermind 28560 points

Hello JH,

If the pull-up is connected. Then I would typically program SYNC_POL_INV = 1 during setup.

Then to generate the SYNC;
SYNC_POL_INV = 0
SYNC_POL_INV = 1

73,
Timothy

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LMK03806: SYNC pin control method