You may have a valid point that a 3.3v converter is more straightforward to the majority of devices. Only one device needs 5v. But now someone ought to verify it (you seem to be a candidate). Test various options to compare cost, stability, parts count, etc. [/QUOTE
Questions:
* As for the 5V load, what is its Ampere amount?
Its hardly 50 or 100mA (Its just a buzzer)
* How do you propose to derive 5v? From 24V? Or from a 3.3v converter? Which is more economical. A 5v converter as a middleman, or separate converters?
Don't Need 5V at all
* Do your loads switch on and off, or change rapidly creating glitches on either the 5v or 3V supply? Do you have devices which get upset by such glitches? Then the decision might be made for you, and you cannot use the customer's easy arrangement. Multiple power supplies may be needed to satisfy some types of devices.
This is the thing that's bothering me. I cannot check it at design phase and need a assembled PCB to do so. If it works, everyones happy and if it doesn't then have to be redone all over again, including PCB design and its gonna cost time and money.
Anyways... I am taking my chances and designing 24V to 3.3V. Lets see how the test goes