2
\$\begingroup\$

I have an application where I need 12V, 5V, and 19.5V from a 24 V power source. I am intending to use 3 XL4016 buck converters and proper fuses that supply the correct voltages to the respective devices. Currently, all the converters and fuses are all over the place and I am wondering whether I can put all the buck converters, fuse holders, and connectors together in a custom made PCB? If so, should I be designing a buck converter from scratch or can I use the schematics diagram(of XL4016) to build the PCB?

Any other design advice for the above scenario is appreciated as well!

\$\endgroup\$
1
  • \$\begingroup\$ You could. With so many buck converters on the same PCB you should probably choose one where you can sync their clocks (or pick another one that has triple outputs). Otherwise you will have to add additional input filtering between each converter to prevent beat frequencies. \$\endgroup\$
    – DKNguyen
    Jun 6, 2020 at 18:18

2 Answers 2

2
\$\begingroup\$

Yes this is possible.

As well as following schematic design ensure you closely follow recommended PCB layout for the buck converter (e.g putting caps near vin and vout pins of buck, ensuring ground is good etc) as switching regulators are very sensitive to the layout of traces/components. Often manufacturer will show a reference PCB layout which is well worth copying especially if you are not sure why/how it works.

\$\endgroup\$
1
  • \$\begingroup\$ Thank you for your answer, I had been researching a lot about DC-DC converters but it seems like an industry manufactured one is more complex than the schematics I could find online. So, what I had planned is to mount the manufactured converters on to a custom-built PCB which has connectors, switches, and fuses, so that it looks much neater than dangling around. Is such configuration advisable in standard practices which has a lot of components to be powered? \$\endgroup\$
    – vinash
    Jun 12, 2020 at 15:41
1
\$\begingroup\$

You can use multiple chips .The standard hard switched peak current mode buck chips will give reasonable efficiency at your low input voltages .there are lots of chips to choose and if you are new to this and in a hurry then why not do this. Beating can be a problem if you use fixed frequency chips because the internal RC oscillators will never be exact so the difference can be audible .Example 3 250KHz chips could be 249 ,250, 252 KHz prospectively beating at 1,2,3KHz .If you lock the chips by whatever means they will all run at exactly the same frequency and you wont have beating .If your chips have locking pins then this is possible .If your chips have external timing resistors then you can set the frequencies way apart so audible beats will not happen .I have implemented antiphase locking schemes that reduce input current ripple due to cancellation .Do this if you have EMC concerns Now be careful with your buck inducters ,They do radiate magnetic feilds and they can pick up magnetic feilds .A christchurch design engineer who was tight for space put 3 bobbin core inducters next door to each other .The bobbin core inducters were from the app notes .All was well ,the design engineer left ,years past along .Then the inducter supply was outsourced to china .The power supplies that had provided Yoeman service then behaved badly at light load .The chinese coil was fine in an individual test power supply .What had happened is the winding direction had changed .So keep the buck coils several radii apart if you do not lock the bucks .Now this one has not happened in my neck of the woods but it could .Free running oscillaters at the same nominal frequency will tend to lock together at a common frequency if there is enough coupling between them .This effect is well known in old school analog electronics and was noted several hundred years ago with pendullum tick tock clocks mounted on the same wooden wall .Dont squeeze things in to tight if you want to avoid suprizes .

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.