UC1842: Component design LTpice model availability.

Tool/software:

I'm trying to locate the component information for UC 1841 ( Programmable, Offline, PWM controller) .  When I look up the PN online it sends me to a TI datasheet but no further information is available.

* Is the part discontinued?

* Is there a similar component to UC 1841 available?

* Is there a radiation hardened version of this component as well? 

 Im trying to locate the respective information so that I can model the component in LTspice.

Thanks,