UCC28722: Could you tell me about how to use UCC28722 ?

Hi, team.

I want to know about how to use UCC28722.

But, since I'm not FAE, I can't consider the reality of the circuit.

So, please tell me the question.

＜Background＞

Customers want to create AC / DC power supply cheaply.

For the purpose of making the cheap schematic,

・Customer is thinking to use secondary side feedback dare to select manufacturers to make cheap transformers.

・Customer is thinking of choosing an external FET of Bipolar type.

Specification

Input Voltage：80V～240V@AC

Input Freaquency：45～66 Hz

Output Voltage：5.3V +0.2V/-0.3V

※Allowable Ripple：± 0.1V

Output Current：1.2A @ TYP, 1.4A @ MAX

Average Efficiency：70%～

＜Question＞

I have considered the circuit while watching examples of circuits related to the following devices.

(UCC28722, UCC28C4x, UC284x, UCC28910/1  etc.)

①Is it realistic to have such a circuit configuration?

②Also, if you want to configure an AC-DC power supply without Isolation,

　can you feed back by resistance division method without using Photo coupler?

※The red circle sees as a device that greatly affects the cost

Best regards,

Masumi Sekiguchi