Ing. coil driver and the SX/28

$WMc%

Helllo All

I need a good driver ( transistor, FET,MOSFET etc.) To drive and·Ing. coil from the output of a SX/28.
Their are so many (drivers) to choose from, So I'm not sure witch would be the better choice with the 5volt TTL
level output from the SX/28?

I have a working code I wrote for this APP. using LEDs. It works fine.

Now All I need is a way to fire the coils and deal with the BEMF.

Any help would be Appreciated


_______________$WMc%_____________

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RS_Jim

HI,
First·question that comes to mind,· What sort of current does the coil draw? Do you have a spec or can you measure the current that it draws?

Velocit

I use a very specialized IGBT from Bosch called the BIP373. It was developed specifically for this application and seems to work well with a wide variety of ignition coils.

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-Paul

Capt. Quirk

What style of·ignition system are you working on, and what coil(s) are going to use?

$WMc%

Veloita'Paola

Thanks for the BIP373, This sounds promising. I did a search for the BIP373 on Mouser's web site and didn't come up with anything. Do You have a source for this device and where to get a DATA sheet for it?


I haven't selected any coils yet. I figured I would wait until I found a good Ing.coil driver for the SX28, and match the coils to it for My Ing. program.

I'll need a DATA sheet to setup the device properly and to insure that no EMF makes its way back the SX28!


___Thanks in Advance______$WMc%_______

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Post Edited ($WMc%) : 4/5/2009 2:00:33 AM GMT

Velocit

Sure thing, here's a little more information on them:

www.megamanual.com/ms2/bip373.htm

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-Paul

RS_Jim

$wmac,
It appears that the driver could be driven with a simple npn transister. The current for the Bosh device is ok for the SX unless you are dirving a lot of other outputs. A simple transister driver would suffice or if you want to really isolate the circuit, us an opto isolator. If you suse the Radio Shack Infared photo transistor and led package, you will have to use a transistor to drive the led as the IR led wants 100 MA! I am using one in a motor drive circuit where I had some groundloop problems between two power supplies. I am using the photo transistor to directly drive a Mosfet which is my motor driver. I belive the photo transistor would directly drive the bosh/
Regards
RS_Jim

$WMc%

Radio Shack Jim

I liked the BIP373 but at $8.00 ea. WOO ,and I have found only one source that carries them.
This device looks more like an injector driver with its MAX output at the start of the pulse and then a reduced current for the rest of the pulse duration?

I like Your opto-iso/MOSFET setup.

What are You using to protect the MOSFET's from "flyback-voltage" from the motor windings in Your motor controller? . I feel this will be close to what I would get using an ING. coil, instead of a motor?·

Should I use something more than a diode and cap with the MOSFET?


_________________________$WMc%_____

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The Truth is out there············································ BoogerWoods, FL. USA

Post Edited ($WMc%) : 4/19/2009 2:11:57 AM GMT

pmrobert

I have successfully used ignition-specific IGBTs from Fairchild for driving coils. http://www.fairchildsemi.com/sitesearch/fsc.jsp?command=text&attr1=ignition+igbt might help you. Fairchild is pretty good about sending samples and the product is much less than $8.00. That said, if this is a one-off project, the BIP373 is well worth the cost. I have seen one of these survive every attempt when we purposely tried to kill it with dead shorts, outside overvoltage, etc. The downside of the IGBTs is that they will very happily burn a hole through your PCB and possibly overheat/destroy the coil if a programming error or unanticipated code condition comes along and they stick on. The BIP just goes into thermal shutdown.

$WMc%

pmrobert

Thanks for the info,The link, and the possible down side to using other IGBTs.
The BIP373 sounds like the best choice here,But I need 4 of them for this project, My 1939 Ford-Ferguson tractor. A V8 motor would really get expensive,I still need coils, etc.

I'll checkout the offerings from Fairchild and compare options.


____Many thanks______$WMc%_______

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pmrobert

Coils can be inexpensively sourced from eBay - there are usually a number of sellers for the Ford COP units - these are very powerful, the COP extension detaches from the coil so you can use a regular plug wire connector and they only need 0.9ms dwell until they're saturated though this does require a 30 amp fuse for each coil with enough current capacity in the LS1 and LS2 coils pop up now and then as well. It used to be the aftermarket was the sole provider of allegedly higher performance coils but the OEM stuff is pretty impressive and sometimes better upon testing. I apologize for the OT-ness, just thought I'd drop some ideas based on my previous experiences.

$WMc%

pmrobert

This is getting better and better!
I'll check this out as well.

___Thanks again_______$WMc%_____

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$WMc%

pmrobert

Thanks again for the links to coil drivers.
·I looked these up, But I'm having a hard time reading the data sheets."never used IGBTs before"
I'm not sure from the data sheet, How much current the gate needs to turn-on fully, or the voltage needed?
I want to make sure I don't overload and I/O pin on the SX/28.

Any clarification on the IGBT lingo would be Great!

I have included the Fairchild data sheets below


__I Like the price @ $2.50 or <___________$WMc%___

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devide by zero

hi

I have experience of this type of design with triggering of high power flash tubes for laser pumping.



I used a fast maxim max628 MOSFET driver feeding the gate of a 900V MOSFET with the drain connected to the induction coil primary.

The max628 can provide upto 2A drive to the MOSFET for fast and efficient switching.

Hope this helps you.

Regards

devidebyzero

pmrobert

I generally use a general purpose NPN transistor switching 5V for the IGBTs. I'll write a short description of the important datasheet parms later today; some items to consider are the current capacity and heat dissipation. These components dissipate the flyback spike internally clamping it at 300-400v, that's one of the parms to consider. Heat is generated with flyback dissipation so a heatsink is necessary. Here's a link to a white paper that, IMO, clarifies device type choice, advantages, disadvantages and characteristics of high power switching devices: www.irf.com/technical-info/whitepaper/choosewisely.pdf

$WMc%

Thanks to all for the info on IGBTs

After I have looked through all the info. I still don't no the trigger current on the IGBTs
I dont understand the lingo in the DATA SHEETs for the IGBTs

I don't want to exceed the (PIN) current rating of the SX/28

How do I fig. the current needed to turn on A IGBT. ????

________$WMc%_________

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Velocit

If you look at figure 18 in the datasheets you posted, you'll see that they recommend a 1kohm resistor in series with the gate if used with a TTL level signal... so, using Ohm's law, you can calculate that it requires about 5mA or so. The BIP373 requires somewhere around 5mA to 12mA.

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-Paul

$WMc%

VelocitaPaola

This is what I was looking for!!!

Many Thanks!!!!!

__________$WMc%_____

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The Truth is out there············································ BoogerWoods, FL. USA