DIYEFI.org Forum

If it's as high as 5.3 it's a reject. Spec says 4.9 to 5.1 IIRC. adjustable can be more finely trimmed. What spec? What's an IIRC? regulator output voltage is approx 5.02V when using correctly spec'd resistors (attention paid to tolerance)should never ever get to 5.30V. The reference voltage for th...

5.4V is about as low as you can go. Any lower and you run the risk of trying to regulate the regulator (the regulator output voltage may be as high as ~ 5.30V).
Thanks,
Huff

FreeEMS will never do a truly good job of CR diesel, ... Hi Fred, Can you elaborate a bit on your comment as I am curious as to what the limitations would be as far as developing a FreeEMS based solution for diesel engines? I understand that "huge code changes" and hardware changes (injec...

Hi Dan,
The schematic shows the upper "REF" resistor connected to the base of the transistor. Should it be connected to +5V SWITCHED instead?

Thanks,
Huff

You've totally missed the "Polyfused TPS (and/or ext MAP) 5V output connected to battery" problem. Otherwise yes :-). I think I would place this more in the "Power Supply" issues bucket than in the "Input Protection" issues bucket. But, since you brought it up (remembe...

For my own clarification and so we are all on the same page - The purpose of the diodes on the input lines are to - 1. Clamp any negative transients on the inputs to ~ -0.3V. 2. Clamp any positive transients to a value less than the maximum value tolerated by the uC before it's own clamp diodes star...

Hi Dan, I don't like the separate net idea though :-( What issues do you see with having a separate net? I realize that running a separate trace around for a V_CLAMP net would present a challenge, but I really feel that it is a "clean" solution to the issue. It would also prevent the (admi...

Perhaps rather than clamping inputs to one of the 5V rails, you could clamp to a separate V_CLAMP net. This would prevent the issues that come up if current is sourced into the 5V rail. If your requirements are that you should be able to handle 1 input shorted to battery, then all you would probably...

Hey Dan,
What I wrote last night still makes some sense to me this morning (thank goodness )
I'd suggest that if you do some more experimentation, that you verify the circuit behaviour at your anticipated maximum frequency (8kHz?) and maybe see what happens at much higher frequencies.
Thanks,
Huff

I have looked at this a bit and feel that I have a basic understanding as to what is going on. Normally (and simply explained), with a differential signal, you have 20k of resistance with a 1nF cap. Using the 1st order filter formula of 1 / (2 x pi x R x C), you have a corner frequency of ~ 8kHz. Th...