[Diy_efi] Re: peak-and-hold injector driver ic's

[Marcell Gal]

Hi Klaus, 

> a good approach. The problem is that during hold time the series resistance
> in the flyback path should be as low as possible 

yes. 


> During switchoff you want a large series
> resistance so that the injector's field collapses as fast as 
> possible. 

No, I don't. If I want to switch it off earlier, I apply
a shorter master injection pulse. (I think that one should
measure the battery voltage anyway, so injector
function vs. pulsewidth would be very deterministic,
with high efficiency and simplicity without the high
resistance wizardry) 

> The PWM frequency is determined by the inductance of the Injector.
> Unfortunately Rcurrent is neccessary (increasing the turn-on time)

unfortunately your Rcurrent is bigger than mine, because
of the current generator approach (R5-Q6).
But that's acceptable anyway. 

Now simplicity is decaying, and you still need
a logic level FET, (which is not a big problem, I just
chose ordinary FET because we have enough supplyV and
others suggested that way)
and twice as many power-components that are essential
(they are more expansive than simple components
regarding space, cooling, handling and cost)
(and also 1/2 IC - I have 1/4) 

But anyway, it's getting nice. 

  Marcell 


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