UCC28881: AC input Buck circuit

I think that UCC28911 can be used to build a Buck circuit by referring to the following materials.
(Replace with UCC28911 instead of UCC28910)

https://www.ti.com/lit/an/snva750/snva750.pdf?ts=1608275350390&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC28910%253Fqgpn%253Ducc28910

However, there is one concern.
There is a part to set the current limit value in the above document. (Set Rpk from the value of Ipk)
Ipk thinks it is necessary to consider the ripple current of the inductor in addition to the output current.
Then, I am concerned that the maximum DRAIN peak current value of UCC28911 below may be exceeded.

Is it possible to design a circuit that meets the following conditions, which was first posted on UCC28911, by referring to the above materials?
・ AC85 ~ 264V input (85 ~ 132V is also possible)
・ 5V 0.6A output
・ Non-insulated type

Regards,

Y.Ottey

Hi, Ottey

TI has UCC28880/1 and UCC28910/1 with integrated FET can support HV Buck. Then the output current should be limited because of the peak current capability of internal FET. And UCC28911's internam FET has the highest peak current capability compare with UCC28880/1 and UCC28910. If UCC28911 cannot meet your spec, I think the controller with external FET should be best. I think that is why Mike O recommended UCC28730 to you in other post. 

Yunsheng 

 Hi Yunsheng

Thank you for your reply.

I thought it would be good to introduce the UCC28730,
but the reference design without a transformer in the Buck circuit has only the following reference design with DC input.
https://www.tij.co.jp/tool/jp/PMP22557

Is there any reference design that is close to the conditions mentioned in the first post with AC input to introduce the UCC28730 to the customer?
(The condition is a Buck circuit without a transformer.)

Regards,

Y.Ottey

Hi Yunsheng

Thank you for your reply.

I understand that PMP20686 is closest to our customer's spec.

I also considered a circuit configuration that meets the following specifications, but I would like to know about PMP22557 again.

If the PMP22557 meets the following specifications, it is necessary to change the parts A to C in the figure below.

・ AC85 ~ 264V input (85 ~ 132V is also possible)
・ 5V 0.6A output
・ Non-insulated type
・ BUCK circuit IC (external FET can also be used)

A: Install a circuit that converts AC to DC (A in the figure below) at the input part.
(It was attached to PMP4443.)

B: B: Change R1 and R2 using the formula for calculating R2 and R3 in the following materials so that Vout = 5V is possible.

https://www.tij.co.jp/jp/lit/an/snva750/snva750.pdf

C: Change FET

Is the above idea correct? Are there any missing parts?

Regards,

Y.Ottey

Hi，Ottey

I think your idea is correct. I don't have more comments to add.

BR,

Yunsheng