MP8017 schematic & reference design

DC-DC Power Converters
1

Hi,

I have 2 questions regarding the MP8017:

  1. Is it possible to supply an external power supply (24v) in a similar fashion to the MP8007/8?

  2. The MP8017 reference design shows a 10uH inductor between VBUS and the transformer, where the datasheet example circuit doesn’t. What is the purpose of the inductor and how does that affect the inductance value of the flyback transformer?

Thanks in advance,

Neil

2

Hi @neil1,

  1. Yes, you can use external power supply with MP8017.
  2. The combination of capacitors and inductor (C1A, L1, C1B) forms a pi-filter. It is ensuring that the input to the transformer is clean. If you verify the Vbus output is clean, you can directly connect Vbus to transformer. L1 inductor does not affect the inductance of transformer.

Thank you
Saurabh

3

Hi @MPSNow_Saurabh thanks for the response and information. Apologies, I misread the 2 caps either side of the inductor.

Could you detail how an external supply might be connected to the MP8017?

The MP8007 has a specific AUX pin to pull up to the power supply voltage to disable the PD switching, what would be the recommended approach here?

Can we feed the external 24v directly onto the VBUS rail with the correct FB and COMP passives?

Thanks again,

Neil

4

Any other MPS engineers like to comment on the above?

5

Hi @neil1,

Please refer to the other post of yours. I’m sorry I misunderstood but MP8017 will not be able to work with 24V adaptor supply.
Kindly keep all your questions in one post in the future to avoid getting flagged by the system.
I’ll be closing this post and keep the other one active.

Thank you
Saurabh