what is the function of pin 5's capacitor of 555

Discussion in 'Homework Help' started by placide, Sep 10, 2012.

  1. placide

    Thread Starter New Member

    Oct 1, 2011
    can you please help me and tell me how does a capacitor which is connected on pin 5 of 555
  2. Audioguru

    AAC Fanatic!

    Dec 20, 2007
    The datasheet shows that the pin 5 voltage affects the pulse frequency and width.
    The pin 5 voltage is 1/3rd of the supply voltage.

    Then if the supply voltage has some ripple signal then the pulse frequency and width is affected if there is no filter capacitor to ground on pin 5.
    bug13 likes this.
  3. WBahn


    Mar 31, 2012
    How does the capacitor.....what?

    Pin five accesses an internal node that is obtained from the supply/ground pins via a voltage divider. This node establishes the reference voltages for the comparators. Adding a capacitor stabilized the voltage by suppressing the high frequency noise. But you can also overdrive the pin and establish your own voltage level on that node and thereby control the thresholds more directly (which is why it is usually labeled the 'control' pin).
  4. placide

    Thread Starter New Member

    Oct 1, 2011
    @ audioguru thx body, you're the man