TOP223Y replacement

There isn't going to be a 100% drop-in replacement but there are a few IC's that will be very close.  With TOP223Y being an older product, I would recommend looking into updating the IC even if you don't make use of all the new features available on the newer IC. 

TopSwitch-HX: 

http://www.powerint.com/sites/default/files/product-docs/tophx_family_datasheet.pdf

This is the most up-to-date TopSwitch IC family availble in the Y package (TO-220).

From this product family, TOP254Y is going to be the closest match.  It has a 1.3A current limit compared to TOP223Y's 1.0A current limit so you're need to use an external current limiting resister.  To make this IC as drop-in compatible as possible, you can use the 3-terminal configuration of the IC found on Page 16 Figure 16 of the datasheet. 

TopSwitch-GX 

http://www.powerint.com/sites/default/files/product-docs/top242.250.pdf

From this product family, TOP244Y is going to be the closest match.  It has a 1.3A current limit and will need the external current limiting resister.  Three terminal configuration is covered in Figure 16 on page 15 of the datasheet. 

TopSwitch-FX

http://www.powerint.com/sites/default/files/product-docs/top232-234.pdf 

TOP233Y is the closest match from this product family.  It has the same 1.3A current limit as the previous two options I list.  Three terminal operation is covered in Figure 13 on page 12 of the datasheet. 

I hope this is helpful.  If you need anything else, please let me know.

-The Traveler

Is the TOP223Y EOL or should I expect any difficulty with being able to continue obtaining this part? We are presently using approximately 250 parts per year.

Gary -

I haven't heard anything about TOP223Y being EOL'd anytime soon but I'm also not involved with that stage of product planning. When a product is EOL'd, we notify customers as early as possible to give them an opportunity for an EOL purchase. 

-The Traveler