We are using a MAX9926 in Adaptive mode to detect zero crossing of a crank signal. Its mode cannot be changed (PCBs made) however we have a particular use case where the signal presented is as pictured. The issue is the adaptive threshold goes to 2/3ds of last peak, so after the big peak, 85mS (the timeout of the chip) of the smaller peaks are missed until it resets on the next cycle.

How can we attenuate the larger pulse only (as the average voltages will all increase as RPM of the engine increases.? Note that average frequency will bvary with engine RPM from say 6000 - 60Khz, so it cannot be a simply filter.

enter image description here

  • \$\begingroup\$ You need to show your current circuit. \$\endgroup\$ – Andy aka Nov 11 '19 at 12:19
  • \$\begingroup\$ This is the ouput measured from a VR sensor directly, there is no real "circuit" as such as this input displays the effects the MAX9926 would give. \$\endgroup\$ – MattyT2017 Nov 11 '19 at 12:20
  • \$\begingroup\$ No it doesn't because you have an adaptive threshold so don't be lazy and less of the BS. \$\endgroup\$ – Andy aka Nov 11 '19 at 12:38
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    \$\begingroup\$ The MAX9926 has the adaptive threshold built in - which we want to retain but condition the signal to attentuate the higher peak - which part was BS? \$\endgroup\$ – MattyT2017 Nov 11 '19 at 13:24
  • \$\begingroup\$ I apologize about the BS suggestion. I thought you were using a regular comparator with external adaptive threshold. \$\endgroup\$ – Andy aka Nov 11 '19 at 13:29

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