Switching current limiter 2

157

01:00:33

Would you think it would work with lm358? I'm asking because of the low control voltage (100mv). I need to regulate a lithium charge and I already dispose of 4.2v. The 100uf capacitor simulate a battery. I set it low value to speed up the simulation. 

published 10 years ago

hurz

10 years ago

I would recommend to use a voltage source instead a capacitor to emulated the battery. And LM358 is definitive to slow and not made for switching as i remember. Use a fast comparator like LT1011 or LT1715. Keep it up.

faceblast

10 years ago

concur with hurz. I get about 12kHz max out a lm358 or 741 and the output follows the +input, it's not linear enough to drive a fet. comparator's are much faster, I can push an LM393 to 160kHz but it needs a drive transistor

aneantisor

10 years ago

Thanks for comments. I think this is why I've never get it to work.

faceblast

10 years ago

yeah making opamp circuits is tricky, I've never got one to work successfully without a CRO. power fets need a faim

faceblast

10 years ago

power fets need a fair amount of power to switch on and off hard too. imagine the gate terminal is a capacitor and you have to charge/discharge it fully to switch the fet on and off. on some fets this can be up to 10nF. to charge that to 10V in less than 1μSec takes at least an amp. the dinky opamps have no chance of driving that. you need a hefty driver opamp chip to do this, or an

faceblast

10 years ago

or another amplifier after the control signal

aneantisor

10 years ago

Thank you for the comment.

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.