PLL on crank angle sensor input

Mark Eidson mark.eidson at tempe.vlsi.com
Tue Mar 4 17:12:30 GMT 1997


I thought of using a PLL to phase lock a higher frequency clock to crank, or
cam sensor to allow more resolution in developing ignition and fuel timing.
The problem I see is the very large dynamic range required.   We have
programmable on chip PLLs that would require software intervention to change
the feedback as the frequency approaches range boundaries.  me

At 11:39 PM 3/4/97 +0800, you wrote:
>At 12:41 4/03/97 -0800, you wrote:
>>I am in the process of designing an microcontroller ignition system, and
>>was wondering - 
>>
>>how common is it to use a PLL on the crank angle sensor input?
>>does any one have a typical circuit design for this part of an efi
>>system?
>
>
>Have no answer, only a silly question..
>Assumng the PLL you ask of is phase lock loop...
>Why would you use it on a continuously varying freq input when PLL is used
>to stabilise the freq of xtal controlled oscillators etc?
>
>If it is to clean up the input, would a one shot m/v or Shmitt trigger be
>better?
>
>Or is it to stabilise the idle speed?
>
>Like I said, I'm not sure what effect you hope for. If there is a good
>reason to use PLL, a Wadley loop might also be worth considering.
>
>;^)
>
>Garry
>
>
>
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