And think they both support to same output voltage and same output current etc. My question is about topological differences of them. BCR321U is definetely looks simpler and it is cheaper.
So, why do I need to use RT8474AGSP? When you consider, they both need much voltage supply and they both need an adjusted resistor for proper current flow, but RT8474AGSP configuration takes more area and so more and more expensive. In addition to that, this configuration is also an option:
If we were constrained by supply voltage, we would use boost led driver chips however, they all are buck structured so why we should chose RT8474AGSP over bcr321u and bcr321u over this simple opamp - npn structure? Where does the value of RT8474AGSP lies?