Thank you for your support.
However, we do not have enough time, please recommend us to reduce mis-operation.
Solution is like below.
1. DC-DC Input : 12VDC
We are using Flyback AC(98Vac to 242Vac) to DC Convertor circuit.
Therefore, voltage 7VDC ~ 20VDC is possible for me, so it doesn't has to be 12VDC.
Flyback output ripple is 100mV p-p(without noise) when it is 12V/3A Load.

2. DC-DC Output Function:
Output Voltage : 1V ~ 5V Variable
Output Current : Max 5A
Ripple and Noise : Less than 8mVrms
V-sensing using distance : 2Meter

We found some components.
LM20125
LM20136
LM20145
LM20146

TPS54550 + Si7110DN

LM21212-2
LM21212-2

For a more confident test, we chose a few package.

Please check whether these components satisfy the specification that I want.
Also, if there is an application note, please recommend.