Flyback design with UCx84x

Lucas Rosa

Hello team,

In my application, I need to design an insulated 24Vdc input to a 5Vdc 1A output voltage source with a minimal insulation of 5kV between primary and secondary. I believe the Flyback topology with a UCx84x controller would be suitable. However, this will be my first time developing a switching voltage source with current mode control. Could you assist me in designing this voltage source? If possible, I would appreciate it if this design could remain offline for secrecy purposes.

Thank you.

over 1 year ago

0 Harish Ramakrishnan5 over 1 year ago

TI__Mastermind 24375 points

Hi Lucas,

Thank you for the query on UCx84x part.

Yes this part could be used for your application. Please expect a response in a couple of days as it is a US national holiday on Monday.

Below is a reference which tells on using this in voltage mode configuration.

https://www.ti.com/lit/an/slua119/slua119.pdf?ts=1708323998192&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUC1844

Regards,

Harish

0 Lucas Rosa over 1 year ago in reply to Harish Ramakrishnan5

Prodigy 110 points

Hi!

Thank you for the reply. For a flyback converter, wouldn't it be better to use current mode control? I am eager to learn how to design an isolated converter with current mode control, and I would appreciate your guidance. Additionally, I am concerned that a standard transformer may not provide sufficient insulation (5kV) between the primary and secondary. I was considering using a separate bobbin or a C-core to separate the coils. What are your thoughts on this? Once again, I would be very grateful if you could assist me in designing a flyback with current mode control.

+1 Hong Huang over 1 year ago in reply to Lucas Rosa

TI__Guru 73345 points

In the datasheet of uc284x there is a detailed process how to design a current mode control flyback

https://www.ti.com/lit/ds/symlink/uc2844.pdf?ts=1708271837159&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUC2844

You can follow this process to make design.

For 5kV insulation you could search if any off the shelf can meet your requirements or you can ask a vender to find an off the shelf available.

if you want to design a transformer yourself you would need to search internet to get the material you need how to make insulation. For transformer fundamental you can refer to the below

https://www.ti.com/video/5402145348001?keyMatch=TRANSFORMER%20DESIGN

https://www.ti.com/seclit/ml/slup132/slup132.pdf

0 Lucas Rosa over 1 year ago in reply to Hong Huang

Prodigy 110 points

Hi!
Thank you for your response. I will design the Flyback according to the datasheet. If anything goes wrong, may I return here for support?

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Flyback design with UCx84x