Injector driver chips? Where?

Martin Mayhead mpm at impltd.com
Tue Feb 27 17:13:50 GMT 1996


> 
> --------
> 
>    In message <9602271012.AA25333 at benjy> , you write:
>  
> | > 
> | > Look at national's LM1949, it is a single piece part, but is very flexible.
> | > It is being tested to also see if it will work as an ignition driver. Very
> | > flexible, and not to expensive.
> | > 
> | > Sandy
> | > 
> | 
> | Beware - this chip does not operate as a switch mode controller and so the
> | darlington dissipates a lot of heat! It does allow for a low part count 
> | solution but fixes the ratio of peak to hold current to 4.
> 
> No... take another look at the 7th page of the data sheets. I
> was playing with this last night.
> 
>                                        John S Gwynne
>                                           Gwynne.1 at osu.edu
> _______________________________________________________________________________
>                T h e   O h i o - S t a t e   U n i v e r s i t y
>     ElectroScience Laboratory, 1320 Kinnear Road, Columbus, Ohio 43212, USA
>                 Telephone: (614) 292-7981 * Fax: (614) 292-7297
> -------------------------------------------------------------------------------
> 
John is of course right but I got the impression from the data sheet that
the switch-mode usage was not reccomended - maybe because of the RFI
considerations. 
The problem I have with using the LM1949 as a switch-mode controller is that
the zener has to dump a lot of power - this may be both more expensive and
more difficult to package than a design using the L584.
Lastly one should beware that NatSemi are pretty good at giving out samples
but when it comes to buying parts such as these (automotive special function)
they always quote me horrendously large minimum order quantities. Maybe this
is no worse than the SGS lead time?

I am really interested to hear about the L9335/9336 chips - they sound like
the (near-)perfect solution.

	Regards, Martin Mayhead



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