Variable current limiting

[antoniobeta]

Hi guys,
I am developing a project on what I have a USB power brick which could give up to 5amps. What I need is to limit digitally the amount of current it gives.
I am thinking on following this guide provided by maxim

https://www.maximintegrated.com/en/app-notes/index.mvp/id/298

But using this IC https://www.maximintegrated.com/en/products/power/protection-control/protection-ics/MAX20313.html

Which gives me the specs I need the problem is that I cant find any IC with these specs and a more amateur/home prototype friendly packaging for example that ic from maxim is only sold on wlp/12 formfactor. The same happends with TI Ics

Does anyone know another method of doing what i want or which would be perfect, an ic that does that on a friendlier form factor?



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[HB9EVI]

I would use a fet, a low R sense resistor, an opamp and dac on an AVR with display; no big thing but already a little bit more complex - and possible with all through hole components

[antoniobeta]

I would use a fet, a low R sense resistor, an opamp and dac on an AVR with display; no big thing but already a little bit more complex - and possible with all through hole components

Could you post a link so I can learn more about it? only with the description I don't know how to do it. [emoji28]


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[rdl]

Current is measured by detecting the voltage drop across a resistor. Current is controlled by adjusting the voltage. All is according to Ohm's Law. Dave explained some ways in one of his power supply videos. #221 I think.

[HB9EVI]

I'm just to lazy to draw a schem; take a logic level fet e.g. IRLZ44 pull it up to VCC with let's say 2k2 to the gate, connect the source over the sense resistor, maybe 0.1R, with VSS, tap source/resistor to the minus of the opamp, the opamp output (cathode side) over a diode to the gate (anode side). to the positive input you feed the DAC output.

Of course that's only if you switch the load on the low side, what is better because of the better fet parameters (Rdson).