If you are looking for TLP781(GB-TP6,F) you may be disappointed to find that this is obsolete. DigiKey carries an alternative to replace it with in TLP785(TP6,F).
This is an upgrade, differing only in minimum current transfer ratio of 50% vs 100% in the obsolete option.
If there are any questions on this, please reply to this post and we will be happy to address them.
Please review the datasheets to ensure the alternative will work for your application.