Ignition updates to the Unofficial FAQ

Randolph > wrote in :

>
> "TeGGeR®" wrote:
>>
>> Got a URL or a pic? I'd like to add that diode.
>>
>> The pics I found showed resistors, but no diodes.
>
> I have looked long and hard at the photos of the ignitor. The darlington
> device is definitely from STM (http:/www.stm.com). The part number is
> hard to decipher, but I am quite certain the first line of the part
> number is BUxy41. I can't for the life of me see if "x" is actually a
> character or just picture noise. The "y" looks like an "8" or a "9". The
> second line of the part number almost certainly is "ZT". This is
> consistent with "BU941ZT", which is an actual STM part number with a
> package type like the one in the ignitor photo. The description is "HIGH
> VOLTAGE IGNITION COIL DRIVER NPN POWER TRANSISTOR". See
> http://www.st.com/stonline/books/ascii/docs/5288.htm for details. The
> data sheet is at http://www.st.com/stonline/books/pdf/docs/5288.pdf. The
> data sheet shows the diode between emitter and collector.

The diode is INTERNAL to the transistor package.
Probably on the same substrate as the xstr.
>
> The IC in the photo looks like it has part number U2226B, and a good
> guess is that the TFK in the first line stand for Telefunken, a German
> semiconductor manufacturer later renamed TEMIC and eventually bought by
> Vishay. I have not found any data sheet for the U2226B, but I believe it
> is an opto-coupler.
>

I found ICs that were specifically designed for ignition control and
driving the Darlingtons,but none with the same pin count of the IC
pictured,nor any similarity to its part number.
I do not believe it's an optocoupler,but a full control IC.Probably with
circuitry to square up(shape) the drive pulse,and provide enough drive
current,and IIRC,the ICs monitored and regulated coil current.(that would
enable faster switching)

--
Jim Yanik
jyanik
at
kua.net