<Ask-help> Buck converter use comparator and ACS712

Thread Starter


Joined May 16, 2019
Hi everyone. I have a small project about constant current buck converter for LED. Base on Poorman's Buck of Ledartist from Instructable (https://www.instructables.com/id/Poormans-Buck/ ), I do some change on original circuit to hanlde atleast 5A.

But, i have problem to known about this circuit and how its work clearly ( comparator working to generate pulse ). And more problem, if i use resistor as current sense, the heat disspation will burn my hand so i need to use ACS712 - 20A to sense this current to lm393.

my question ( hope u can answer me ):
1. How lm393 work to generate pulse ? is the block of R1-R3 + C4 or block of R10 + C7 ?
2. How to calculate and what does it mean of C4 ?
3. I want my circuit run at atleast 200Khz - 400Khz ( better if they fixed ), so my value for RC is right ?
4. ACS712, Itself VIOUT waveform is ?

Thank friend alot. hope u all answer my fool.