• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

DALI TX opto should have higher CTR?

Not open for further replies.


Well-Known Member
Figure 5, page 3, of the following DALI application note (AN1465) shows optos being used to isolate both TX and RX DALI signals….

AN1465 Application note:

Though surely, the TX opto should be a TCLT1009 (CTR of TCLT1009 = 300%) and not a TCLT1000 (CTR of TCLT1000 = 50%)?

Also, surely the RX opto should be a TCLT1000, which it indeed is.

The reason that the RX opto should be a TCLT1000 is because it has a lower capacitance seen at its emitter pin which means the rise time of the emitter can be quicker. Do you agree?

TCLT100X opto datasheet:


Well-Known Member
Don't look like it would matter the TCLT1000 would work fine for both as shown.
Not open for further replies.

Latest threads

EE World Online Articles