LM5122: About Non-Synchronous circuit

Tsukui Yusuke

Guru 21930 points

Part Number: LM5122
Other Parts Discussed in Thread: LM5155

Hi,

My customer wants to use the LM5122 with Non-Synchronous circuit.
Can this device be used by replacing the FET with a diode?

Regards
Yusuke

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Yusuke,

I think it is possible but why do you select this device, maybe we can just use non-synchronous boost controller.

0 Tsukui Yusuke over 5 years ago in reply to Jasper Li

Guru 21930 points

Li-san,

Thank you for your response.
I will check the background of LM5122 consideration to the customer.

>I think it is possible
→Can you introduce a circuit example?

Regards
Yusuke

0 Youhao Xi over 5 years ago in reply to Tsukui Yusuke

TI__Guru* 78080 points

Hi Yusuke-san,

You can replace the LM5122's sync FET with a diode. But like Jasper mentioned, it seems to be a waste and not cost effective. For non-sync boost, you can consider the LM5155.

Thanks,

Youhao Xi, Applications Engineering

0 Tsukui Yusuke over 5 years ago in reply to Youhao Xi

Guru 21930 points

Hello Xi, Li,

Thank you for your kind support.
>I will check the background of LM5122 consideration to the customer.
Customer wants to perform an interleave operation.
For this reason, it was selected the LM5122.

Could you tell me your concern about interleaved operation using diodes?
(BST, HO, SW pin : open )
I will attach the customer's circuit image.

5722.LM5122.pdf

Regards
Yusuke

0 Youhao Xi over 5 years ago in reply to Tsukui Yusuke

TI__Guru* 78080 points

Hi Yusuke-san,

The rectifier diode or Sync FET does not affect the interleaving operation. Those non-used pins can be left open, but I would ground SW pin, and use 10k each to connect BST or HO to GND.

Thanks,

Youhao

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LM5122: About Non-Synchronous circuit