Can anyone provide any info/datasheet on this IC

[RSion.1]

It was part of an RS232 board on a 20 year old CNC machine

[Peter BENSCH]

Welcome, @RSion.1​, to the community!

It is was the ITA25B3, a bidirectional transil array (TVS) that has been obsolete for many years.

You will find the data sheet using your favourite search engine, the first hit of my one showed it on position 1. It contains 10 Transil (TVS) with 300W (8/20µs) and a breakdown voltage of 25V each.

Does it answer your question?

Regards

/Peter

[Tesla DeLorean]

https://octopart.com/datasheet/ita25b3-stmicroelectronics-347782

[Tesla DeLorean]

https://www.ebay.com/itm/134061732518

https://www.ebay.com/itm/372124354041

[RSion.1]

Many thanks for the very fast answer. I misread the B for an 8!

Do you know if it fails if it is likely to fail with the input open circuit?

[RSion.1]

Also is there a pin for pin replacement part available?

[Peter BENSCH]

Typically, one only notices the failure of a TVS when it either has a short circuit due to overload. If, which rarely happens, it no longer has a TVS function, the protective function would no longer be given, but this can only be sensibly checked after removing the TVS and measuring it with a current-limited power supply unit.

No, there is no P2P replacement from STMicroelectronics available. The only similar device is the ITA25B1R, which can only protect four TVS data lines. It does not make much sense to build three such components into the layout, as the necessary wires would impair the protective function too much (do you need them for production or repair?).

But if you don't need too many replacement types, you might still find leftover quantities at the various handlers on the internet, e.g. the one mentioned by Tesla?

Good luck!

Regards

/Peter