This is probably a question to change to the JLCPCB category rather than LCSC because JLCPCB stock is separate from LCSC. Are you looking for Buck or step down **regulator** chip (which has an internal switch) or a **controller **(which uses an external switch transistor)? Have you searched for any of the TI Simple Switcher series devices? :)

The search for JLCPCB needs to be improved to get it anywhere near the functionality of places like Farnell, RS-Online or Digikey. The way to work round this is to go to the semiconductor manufacturers first to find suitable parts then search for specific part numbers in the JLCBPCB SMT Library Search. Go to TI.com Search for DC-DC > Buck Converters 36V in, 12V @ 3A out: [https://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/step-down-buck/buck-converter-integrated-switch/products.html#p238min=1.5;30&p238max=30;60&p634min=-3;12&p634max=12;90&p451max=3;3.5&p212max=41.36807817589576;100](https://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/step-down-buck/buck-converter-integrated-switch/products.html#p238min=1.5;30&p238max=30;60&p634min=-3;12&p634max=12;90&p451max=3;3.5&p212max=41.36807817589576;100) Enter part numbers of candidates into JLCPCB SMT Library Search and find: [https://jlcpcb.com/parts/componentSearch?searchTxt=LM22676](https://jlcpcb.com/parts/componentSearch?searchTxt=LM22676) [https://jlcpcb.com/parts/componentSearch?searchTxt=TPS5430](https://jlcpcb.com/parts/componentSearch?searchTxt=TPS5430) You can do the same for any number of manufacturers.

"The search for JLCPCB needs to be improved to get it anywhere near the functionality of places like Farnell, RS-Online or Digikey." Understatement of the year ! They could also do with better links into EasyEDA as I spent all yesterday evening trying to assign the correct LCSC part numbers to the BOM yet it still had glaring errors.     At one point it was insisting on putting an 0805 resistor onto 0603 pads ! It also seems to love having separate BOM lines for the same part number.  Not per component, but if I use a dozen of one item, it's often there with 2 on one line and 10 on another.  And it's not even the next line, but lower down.  Weird !

Their search works OK for me. Go to the category **Power Management ICs /   DC-DC Converters** You can use the filters on top. You can use CTRL and SHIFT to select multiple/ranges. Recently it resets scrolls positions for some reason. And also there's some lag while it processes selection to adjust other options to make sure you cant select incompatible selections. Then click apply. A few options: TPS54331DR TPS54531DDAR XL4015E1 LM2596R-5.0 LM2596SX-5.0/NOPB LM2596T-3.3 LM2596T-5.0

@EdHayes3, Yes, you can find a load of converters on the JLCPCB SMT Parts page but the OP wanted a step down or buck converter with specific input and output voltage and load current ranges. The filters on the JLCPCB SMT Parts pages are no help at all in finding converter parts that have specific characteristics. You have to either look at - and then open the datasheet for - every part in turn or have some idea of what part numbers you are looking for before you start searching the JLCPCB page. Compare that with the search and filtering tools - and then try finding parts - on sites like Element14, Farnell, RS, Digikey or Mouser and you see the difference. And then you have the rapidly changing stock levels to complicate the choices.

@andyfierman Agreed JLCPCB parts page is limited. He actually said LCSC :D. I do my searching there anyway. It's mostly the same thing. I wish there was a flag there for JLCPCB, rather than having to go back over to jlcpcb.com and searching by lcsc part number. I guess things could be worth. It's nice pasting a part number into EasyEDA and it just pops in perfectly. So I can deal with the limited jlcpcb page, it's kindof fun hunting for parts some times :D

@EdHayes3, But at the end of the post, the OP said: "...would like to have **jlcpcb** assemble them..." so, whether they realise it or not, they need to be searching JLCPCB not LCSC. I agree with you about using LCSC to find parts and then using the LCSC part code to find them in JLCPCB but it is just such an unnecessarily slow process. The filters in LCSC are better but still need to be improved.

FYI, quick update. The TPS54331 is a basic part at JLCPCB. Good price. It does accept 26v input, and with some additional parts (like any other regulator) will output 5 or 12v just fine. Just got a PCB made with several TPS54331 actually, and I'm able to get 3a, 5v out  from 24v no problem. Very stable.