I'm waiting to remove the reliance on linear voltage regulators and moving towards a buck converter for my projects, I'm planning on integrating the buck converter on the next version of PCB i get printed.
I'm going to use a LM2576HV-5.0 (fixed output voltage of 5.0 volts with max 3amp draw). This gets a pretty high efficiency rating compared to a linear voltage regulator like a LM7805 or LM7808.
Scenario:
12v volts input
Max draw i'm seeing when I am powering my project and I measure current at the 12v input I am averaging 0.150 to 0.200amps.
I have a couple of questions:
Can I reduce any of component sizes detailed in the above schematic, given my input is fixed @ 12volts and my current is never more than 0.250amps, i'd be happy to design for 1amp max potential?
I'm currently doing some tests on the LM2576HV-ADJ version, (waiting for fixed version to arrive) and when I'm simulating 0.750amps @ 5v using the voltage divider setup method the LM2576 gets pretty warm/hot, nothing like an LM7805 with the same load, but just wondering if this expected as its just what is generated when pulling current through and not an efficiency/setup issue?
Is there a better way to do this or better component, given my input/out votlage requirements and current draw needs?
Lastly, which i'm confirming is ive read the ESP32-WROOM-32U (espressif) can run fine with 5v on the 5vin pin, other posts say 7+ voltages is needed. Given USB only provides 5vs, surely 5v on 5vin pin is ok?
I do not know what your load is but you have this per the data sheet: a ±4% tolerance on output voltage within specified input voltages and output
load conditions which should be good for most applications. The chip uses 3.3V so 5V would work but is close depending on the tolerance of the regulator on the module. Me being on the conservative side would opt for 7V. That will allow the regulator on board do its job and cool your external regulator a little as well.
A couple of points about the LM2576: it’s a very old design part, not a good choice if you’re doing a new design. It runs at 50Khz so the inductor is much larger than need be with a modern design part. The more important point is if you’re buying them from unknown distributors, you can be assured they are counterfeit parts that are very crappy knock-offs that will not even get close to meeting published specifications.
That certainly sounds like what happened if you have a part getting hot with a minimal load. Of course design can affect that but the source of those parts is critical in order to receive and actual name brand device. What’s printed on the part means absolutely nothing.
One last thing. It is really pointless to purchase HV version parts when you’re applying 12 volts.
If space matters, here’s what you can do with modern parts, the entire circuit is about the same size as a to-220 package.
Hi, yeah definitely concerned about knock of parts, only getting them from local electronic stores and https://au.rs-online.com/, assuming quality wise these should be ok.
Didnt know the LM2576 units are old school, bugger. The pololu looks interesting, great size. Are they good quality parts in that unit?
Just thinking about load, if I'm lets say 0.250amps @ 12v that is 3 watts of power. 3 watts @ 5vs = .6amps, so over the 500mV?
Size of the system isnt really and issue, and I built by PCBs using mostly TH design so all parts can very easily be changed.
Can I suggest you look at the datasheet for that and other switchmode devices. LAYOUT is all important due to the fact that the frequencies involved can be affected by impedances of your PCB tracks, and the need for a ground plane.
awesome thanks for the info, i have been reading up allot about PSU design and it definitely is complex. I think you have me convinced and I will go with the 1amp version of the pololu thing
