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Question on peak detector

Poh Kok Keng
Genius 5112 points
Other Parts Discussed in Thread: TIDA-00289

hi,

I need to capture the middle peak of the current waveform as indicate in the green colour waveform below.This is the surge for the solenoid which happened within 2Mhz to < 10MHz.

I have look at the TI reference design here: http:/www.ti.com/tool/TIDA-00289, the zoom in waveform will be very similar to this but need to captured this within 2Mhz to < 10MHz.

This reference design doesn't seem to be able to caputed 2 MHz to <10MHz signal. Do you have a better suggestion on the part which can do this?

Rgds,

kpk

  • 0
    TI__Expert 3126 points

     

    Hello ,

    I assume you are using the peak detector with the value of the components as shown above

    Please calculate the rise time of the peak signal that you want to capture i.e time taken for signal to reach 10% to 90% of the final output

    Now make sure that the peak detector 5RC ( 5 times “time constant” ) is lesser than the above signal time  constant

     

    please size your cap C4 and resistor R26 to make sure you satisfy the above condition

     

    Also the diode will have a on state resistance (forward resistance) please account for it by adding it to the 100 ohm resistance while calculating your charging time constant