LM5122-Q1: Dual phase design

Alessandro Sorrentino

Part Number: LM5122-Q1
Other Parts Discussed in Thread: LM5122

Tool/software:

Hi all,

I have designed a single phase boost converter using webench, this is:

I want to use the same design for a dual-phase configuration, how i can do that? The testbench near the lm5122 remain the same but i have just to parallelize the two boost using the syncout and syncin port?

Thank you,
Alessandro

over 1 year ago

+1 Niklas Schwarz over 1 year ago

TI__Mastermind 30330 points

Hi Alessandro,

Thanks for using the e2e forum.
You are correct, for using the LM5122 with two or more phases, it is recommended to use the syncout feature.
A description on how to connect pins within two ICs can be found in the datasheet:
https://www.ti.com/lit/ds/symlink/lm5122.pdf

The webench values are still valid, but you need to account for both phases taking only 50% of the current and therefore requirements for sense resistor, inductor and compensation may change.

Best regards,
Niklas

0 Alessandro Sorrentino over 1 year ago in reply to Niklas Schwarz

Prodigy 40 points

Hi Niklas,

I configure it in dual phase but without result. Vss is ramping but Vcc on the second converter is always zero, what is the cause?

Regards,
Alessandro

0 Alessandro Sorrentino over 1 year ago in reply to Alessandro Sorrentino

Prodigy 40 points

Also i configure it with both mode pin to zero, is it okay?

0 Niklas Schwarz over 1 year ago in reply to Alessandro Sorrentino

TI__Mastermind 30330 points

Hi Alessandro,

If only one phase has active VCC, there should be a problem within the schematic.
Can you double check the connections of VIN and UVLO pin? If the second phase is still in shutdown, there will be no Vcc voltage.

Yes, it is okay to connect both mode pins to GND.

Best regards,
Niklas

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LM5122-Q1: Dual phase design