Injector Driver Module

[Don.F.Broadus at ucm.com]

One thing I forgot to mention is that when a power transistor is turned on
the voltage drop across the transistor is around
.7 to 1.5 volts. The  V drop *  current is the power dissipation. 1.5v*1 Amp
= 1.5 watts. Since the injector is typically 16 ohms most of the voltage
drop and dissipation is in the injector. 16 volts*1 amp = 16 watts. With a
low resistance injector the majority of power is still dissipated in the
injector and not the driver transistor.
 
Take care     
 
Don      


-----Original Message-----
	From:	Gregory A. Parmer [SMTP:gparmer at acesag.auburn.edu]
	Sent:	Monday, August 10, 1998 11:47 AM
	To:	diy_efi at efi332.eng.ohio-state.edu
	Subject:	Re: Injector Driver Module


	On Thu, 6 Aug 1998, Jose  Rodriguez wrote:
	>   I am designing an injector driver module.

	If you haven't do so already, you should compare
	your design to the EFI332 one at
	http://efi332.eng.ohio-state.edu/efi332/hardware.html


	>   Injector coil resistance: 1.5 ohms (it could also be 2.3 ohms)
	<snip...>
	>   If all 8 injectors could be on 85% of the time, then the maximum

	<snip...>

	A few more quick thoughts. GENE already pointed out that for a
4cycle
	engine you're talking about half of 85%. Also, I think most
	OEM port injectors have a higher resistance (15+ ohms?).
	This makes your power consumption figures look **much** better.
	Also, mounting your module in the car interior as most OEMs
	do helps your underhood heat problem.

	When's the prototype scheduled?   :)
	-greg