LM5149: LM5149 dual-phase 15A regulator by MCU

Federico Battaglin

Part Number: LM5149

Tool/software:

Hello to All,

for a variant of a project of a power supply, we need to use 2 LM5149 in dual phase mode, as suggests the application circuit 4 at the paragraph 9.2.4 in figure 9.40 of data sheet (SNVSBV4A). But the FB pin will be connect not only to output voltage (of course) but also to a MCU using a few resistors in order to vary the output voltage. With one LM5149, it's easy to do.

But it's not clear how implement this on dual phase regulator.
In reference to the diagram before mentioned, the connection to MCU will be done on Primary LM5149, as in the same of single phase and this is ok.
But how connect the FB pin in the Secondary LM5149?

The same question on PFM/SYNC pin on Primary LM5149... In my diagram, base on single LM4159, this pin is connect to AVDD pin... Is it possible to use the same connection on Primary LM5149?

Thank You and Best Regards
Federico Battaglin

3 months ago

0 Youhao Xi 3 months ago

TI__Guru 73830 points

Hi Federico,

Thank you for designing with our products. The experts of this device are currently out of office, so let me study this and get back to you in the next few days.

Regards,

Youhao

0 Federico Battaglin 3 months ago in reply to Youhao Xi

Prodigy 40 points

Dear Youhao,

thank You for your reply... ok, I will await for...

Best Regards
Federico

0 Youhao Xi 3 months ago in reply to Federico Battaglin

TI__Guru 73830 points

Hi Federico,

Thank you for understanding my situation. This is what I found out so far:

1. Yes you can adjust Vout by controlling the primary IC's FB like you would do in a single phase design. The FB of the secondary IC can be used for PFM/FPWM control.

2. Yes you can use it the same way as in a single IC deesign.

Hope this helps.

Best Regards,

Youhao

0 Federico Battaglin 3 months ago in reply to Youhao Xi

Prodigy 40 points

Hello Youhao,

thank You for your reply, but I don't undersand:

1) Your answer "The FB of the secondary IC can be used for PFM/FPWM control.".
How and where will be connected FB of secondary IC?

2) Yiur answer "Yes you can use it the same way as in a single IC deesign".
If I understood well, I can connect PFM/SYNC pin (of secondary IC) to AVDD... is it correct?

Thank You and Best Regards
Federico

0 Federico Battaglin 3 months ago in reply to Federico Battaglin

Prodigy 40 points

I read better the data sheet and there's the figure 8.8 that expanis the connection...

Thank You in any case...
Best Refards
Federico

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LM5149: LM5149 dual-phase 15A regulator by MCU