[Diy_efi] Re: injector current-feedback driver
bcroe at juno.com
bcroe at juno.com
Tue Mar 4 00:02:45 GMT 2003
If you want to drive an FET with 5 volt HC logic, you
ought to use a LOGIC level input FET. Trying to drive
the generic 4 volt threshold FET with 5 volt logic really
doesn't do the job.
In addition, some current is required during the state
transitions, so I use an AC chip for driving repetitive or
time critical apps. Just insert the AC after your HC, OK
to parallel sections for more drive. I insert a series
resistor to limit gate drive current to 24ma per section,
if its too slow that way, try a full blown FET driver chip or
possibly an FET with less input capacity.
Bruce Roe
3 Mar 2003 Lasse Langwadt Christensen <langwadt at ieee.org> writes:
> Marcell Gal wrote:
> > Hi Mark,
> >
> big snip
> >
> > What if Q1 is a darlington?
> > What FET do you recommend for max 6A? Do I need a FET-drive
> > than (like megasquirt) or 5 Volt HC output is fine for
> > driving FET gate?
> > thanx:
> > Marcell
>
> I friend of mine has been using buk108-50 for saturated
> injectors with the gate driven directly from a 5volt cpu.
>
> it has buildin over-current and temperature protection, and
> overvoltage clamping at around 50volts so it doesn't need
> any external clamping(1)
>
> -Lasse
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