UC3843 for a motor controller?

[MrHeckles]

I am tossing around a few ideas as to making a motor controller for an electric wheel chair type thing (it'll need to handle a fair current from a 24v motor).

I was thinking that pehaps the UC3843 would be a good PWM generator for this. My reasons for thinking this (which may be incorrect) are that it allows variation of the PWM duty cycle between 0 and (close to) 100%, and it has built in current limitation, and undervoltage lockout.

Could anyone tell me if I am correct in these assumptions?

Also, am I right in thinking that to make it variable duty cycle, I can just make the Rt a variable resistor?

 

[audioguru2]

I didn't look at other manufacturers but Fairchild is discontinuing it soon, so I wouldn't use it.

View attachment 37745

 

[MrHeckles]

I was going to use the UC3843BN from ON.

It's cheap and easily available for me.

How about the above questions?

Is there a better chip for providing a variable duty time PWM signal with current limiting around (that I can actually get in NZ)?

 

[MrHeckles]

Now that I think about it. If someone could explain to me how to setup a good current limit system, the PWM generator based on the dual opamp in another thread could probably be used.

The PWM would be used to drive a half bridge driver at this stage. Later I may go to a full bridge, but not until I know a bit more about whether I can build it.