LM5575: Sync pin - as a jitter input

Srinivasu V

Part Number: LM5575

Hello,

Can I use sync pin as a software jitter input. ( actually, to avoid the Radiated emission we wanted to implement this option.)

if yes, please let me know, what are components, I have to consider?

or This is pin only for synchronizing the Multiple LM5575-Q1 devices together?

over 4 years ago

0 Ankit Gupta95 over 4 years ago

TI__Expert 4555 points

Hello Srinivasu,

Yes, you can use this pin to reduce EMI.

I would recommend following Oscillator section in the Electrical Characteristics table in datasheet while applying the External Clock.

Best Regards,

Ankit Gupta

Application Engineer

0 Srinivasu V over 4 years ago in reply to Ankit Gupta95

Intellectual 360 points

Hi Ankit,

Thank you for updates!.

Do you have any reference schematic which is SYNC related components added?

and, I have one more question on SD( ENABLE pin)

supply input is 18 to 36V and clod start time battery supply will go down up-to 6V.

MY question is, Can I use below circuit for enable pin? or this voltage divider, will act as a UVLO?

0 Srinivasu V over 4 years ago in reply to Ankit Gupta95

Intellectual 360 points

Hello Ankit,

I have already considered RT - 12.1K ( 450Khz)

datasheet says that, "The external clock must be of higher frequency than the free-running frequency set by the RT resistor"

Here, I wanted to understand, external clock Should be 450Khz to 550Khz is it?

regards,

Srinivasu

0 Ankit Gupta95 over 4 years ago in reply to Srinivasu V

TI__Expert 4555 points

Hello Srinivasu,

Yes, you are correct. The external clock should be higher than the RT resister set frequency. In your case, where the Internal set frequency is 450KHz, you should apply an external clock from 450KHz to 550KHz. Hope this helps!

Please close the thread if you think you got the answer you were looking for. Thanks!

Best Regards,

Ankit Gupta

Application Engineer

0 Srinivasu V over 4 years ago in reply to Ankit Gupta95

Intellectual 360 points

Hello Ankit,

Thanks for the information.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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LM5575: Sync pin - as a jitter input