ESP32 Forum

Hello,

I am making a device based on an ESP32 and all the sensors i need to connect are 3.3v
I was looking for a small power supply (AC / DC converter) and bought a few of these:

Multicomp Pro MP-LS05-13B03R3 ([iurl=https://nl.farnell.com/multicomp-pro/mp ... 4006?st=ac dc]MP-LS05-13B03R3 - Multicomp Pro - AC/DC PCB Mount Power Supply (PSU), 70 to 430VDC, ITE (farnell.com)[/iurl])

The stupid i am, i bought it and as they arrived i started to look at how to use them. To be honest, i thought i would just connect 230v to the pin 1 and 2 and get 3.3V on pin 3 and 4 or 5 and 6 (didn't know the exact difference between the 4 output pins).

Now i started to look at the datasheet ([iurl=http://www.farnell.com/datasheets/3167206.pdf]3167206.pdf (farnell.com)[/iurl]) and see that there is much more to connect than just the 4 wires :smiley-eek-blue:


I think i should go for this design:




I think i understand how to add the fuse, resistor and CX capacitor, but i cannot figure out what LDM is, and what MOV is, also i am not quite sure i understand what everything is behind the outputs 3 till 6.

If anyone would help me a bit i would appreciate it really much.

Thanks a lot!

A MOV is a Metal-Oxide Varistor. It effectively shorts any voltages above its rated voltage to ground, making sure it can't get to the power supply. LDM seemingly is a Differential-Mode noise supressing inductor; I'm less familiar with those. I see Murata makes specific inductors for that, perhaps you can use the parametric search on e.g. Digikey to find more.The rest of the stuff behind pin 5 and 6 is more noise suppression: C2/L1/C3 form a Pi network, acting as a lowpass filter, to keep any switching crap or stuff that carries over from the line voltage side out of the rest of the circuit. The TVS is a Transient Voltage Suppression diode; if anything (like EMC) inducts into your circuit generating a spike on your supply rail, this will eat it up (It works similar to a MOV, but for lower voltages.) C4 is for general stabilization, and RL not a real component but means 'connect the rest of your circuit here'.

Note that if you want to test, you can probably leave all of these off (aside from C4) and the power supply will still work. However, if you want a robust circuit you can throw into mass production and you need to comply with EMC regulations, you'll probably want to keep most of these in.

Thank you for the complete answer. This is not for mass production or for sale. It is for a device that will be placed in every room of the house to measure temperature etc.

C4 is a capacitor? How can i calculate the value of it?

And id i just use this module with the C4 capacitor, will this be safe enough to use for my perpose? It will be on 24/7

Thanks again!

It's 0.1uF, see the table on top of page 4 of the datasheet. I'm actually changing my PoV that you can likely leave most of these components off: That datasheet is pretty adamant that some of the components are actually required, so you may want to design them in anyways as the manufacturer may not guarantee proper working/safety if you don't.

It may be better to use a 5V plug-in power supply instead of the item from Farnell and to use a 3.3V voltage regulator such as this example. Then you will simply need 2 capacitors and a barrel socket. This would avoid hazardous mains voltage.

The meaning of L is still LOAD, which is Load from memory into register.

Varistor is also simmiliar to Transil Diode. The type of protecting semiconductor diode with method of operation similar to varistor, which is designed to protect sensitive electronic components from electrical surges. We distinguish unidirectional and bidirectional TVSs.
https://911electronic.com/transil-diode/