Anyone have a favorite Dual Darlington (NPN)? I was just told today that the part we were using (Zetec ZDT605) has been discontinued. I'm just about ready to finish a board, but need a current mirror and was planning to steal one off another (similar) design. Since we can no longer get the Zetec part I now have two boards to redo.
Other ideas?
-- Keith
DigiKey still has about 479 of them, maybe you can buy some breathing room. What current does your current mirror run at?
I wonder if these can work well in a mirror? It's a painful matter of requiring good Q1a-b beta match to achieve Q2a-b Vbe match. If there was an extra pin available, one could add a Vbe resistor and fix the problem, but....
That may be enough to prevent a re-spin of the current board but=20 won't be nearly enough for the new product. I didn't see any supply=20 there earlier today. I'll certainly snarf them up tomorrow. =20 Thanks!
The current design requires 100mA or so, to share (DC) power from=20 two (AC) balanced lines. The new application is simply a voltage=20 monitor needed to detect when the line/termination drops out. I=20 need to share the load of an opto-isolator between the two balanced=20 lines, so a couple of mA.
It works well enough in the power sharing application now. I'd like=20 to do better (eliminate the whole thing), but time and risk is=20 getting to be an issue. It's easy to justify "works".
--=20 Keith
FWIW, Quest also claims to have 3800 pcs. of the ZDT605TA for 30 cents apiece.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.