Current limiting resistor for buck converter?

[Pariston]

Hi,
I have a quick question. Should I use a current limiting resistor for 102-VXO7803-500-M-CT-ND (https://www.digikey.ca/en/products/detail/cui-inc/VXO7803-500-M-TR/11569239). Input voltage 24V.

[Manul]

On the input? No, you should not use any resistors. You may use a fuse if you want. You may also use noise filters, but you probably do not need them.

[Zero999]

Don't use a series resistor. It will reduce the efficiency and could cause instability. The output is short circuti protected, but it's a good idea to add a fuse to the input, in case a fault develops inside the switching regulator.

[Pariston]

Thanks for replying!

I have a question on the current rating for this fuse. Circuit is powered from the wall through SDI36-48-U-P5 (48V DC) power supply which has Barrel Plug on the output side. Is there any danger to the circuit, the moment plug is connected? I am afraid of initial spark to cause damage in some way.

Additional information:
48 V power supply is required for my high power led and can not be avoided
Buck converter operating voltage is 5V to 36 V, so, I decided to power this buck converter with 24V zener diode on the line, PDZVTFTR24BCT-ND‎ has maximum zener current of 40 mA. Should be enough for this tiny buck converter.

[Manul]

Fuse for that buck converter? Roughly, if it is 3.3V 500mA max output, and the input voltage is 24V, max input current should be around 500mA / (24V / 3.3V) * 1.2 = 82.5mA. I choose 1.2 multiplier, because likely efficiency could be around 80-95%.

About 48V and zener. In my opinion it is bad idea. You should use a converter.

[Zero999]

Thanks for replying!

I have a question on the current rating for this fuse. Circuit is powered from the wall through SDI36-48-U-P5 (48V DC) power supply which has Barrel Plug on the output side. Is there any danger to the circuit, the moment plug is connected? I am afraid of initial spark to cause damage in some way.

Additional information:
48 V power supply is required for my high power led and can not be avoided
Buck converter operating voltage is 5V to 36 V, so, I decided to power this buck converter with 24V zener diode on the line, PDZVTFTR24BCT-ND‎ has maximum zener current of 40 mA. Should be enough for this tiny buck converter.

The zener diode would have to do in series and its current rating would depend on the load connected to the buck converter, but it's not the right way to do this, which is to use a DC:DC converter rated to 48V in.

https://www.digikey.ca/en/products/detail/mornsun-america-llc/URB4803MT-3WR3/13168103