L- Jetronic Integrated Circuit Dies

[busboy25]

Figure I would post this in the bay window section since I feel like the interest in L-Jetronic is probably highest here. For the last few years I have been reverse engineering L-Jet ECUs. This is what I have ready to share.

These are some photos of the exposed dies from the 3 integrated circuits used within the ECUs. Evilmonkeyzdesignz on Instagram was nice enough to open them up, and take all the photos here and in this google drive.
https://drive.google.com/drive/folders/1noCmkkhKX3-PVZtCx0w53LZqOhxiOYjr
The google drive includes the many more photos at full resolution since to load them to thesamba galley I have to reduce there size.

These are from a 75 Bug. Some of the caps on the board are date coded from Augest 1974.
VW part number 043 906 021
Bosch part number 0 0280 000 105
This IC are the same as ones used in 76 Fed Bay ECUs. I don't have any ECUs later than 76 but I know some of the later ECUs use DIP packaging and another style that I don't know the name for.

At some point, I will update this with details on the pin outs from these ICs.

First I want to show this block diagram from a L-Jet manual (page 17) included in the drive that I use to name each of the ICs. And a timing diagram from page 19.

The first IC used in the injector pulse width process. It takes the ignition coil feedback signal after it have been put thru a voltage divider and diode is used to clip the peak voltage (or at least this is my assumption). The can is marked with a Bosch logo and 220 062 Ch 3035. It has 10 pins. The first picture show the IC, after opening, in the plastic seat that is used to position the pins in the board. Second is of the die.

The second IC is the Division Control Multivibrator (DSM). This IC solely acts with the AFM inputs and produces a pulse that is described as the "base" injector pulse. The can is marked with a Siemens logo and CJ10 e9. It has 14 pins.

The third IC is the multiplier stage and triggers the power transistor that drives injectors. It corrects the base timing pulse for temps, battery voltage, and other inputs. Base on what is noted on Page 27 I believe that lambda adjustments are made to the DSM not the multiplier. The can is marked with a Siemens logo and CJ21 e9. It has 14 pins.

This is a picture of the board with the IC still installed. The heat fin "hats" put on each of the 3 IC have been removed. The lower right hand IC is the pulse shaper. The lower left is the DSM. The upper left is the multiplier stage.

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76 Bay - 2056 Type four

[SGKent]

good job
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[RawUmber]

This appears to be another picture of the DSM die, from Bosch circa 1975. Evilmonkeyzdesignz's pics are beautiful and hard to beat, but thought it nice to add this vintage photo.

While I was at it, added higher resolution Complete Schematic Pulse-Timing Diagram and Block Diagram of the ECU.

[mikedjames]

I was intrigued by this, started hitting Google with searches " bosch fuel injection multiplier" and patents begin to appear..



https://patentimages.storage.googleapis.com/ad/ca/7c/197d93dca03adc/US3483851.pdf


One thing is that with modern surface mount components its quite possible to build replicas of ICs from the 1970s and the footprint can be comparable with the IC solder footprint..


There are probably less than 10 transistors in each IC, and each "component" has its own visible layout- snaking polysilicon resistors, bipolar transistors and so on..
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