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Regarding NE555

Ajith Sasidharan
Prodigy 50 points
Other Parts Discussed in Thread: NE555

Hi,

   I configured for a 48kHz astable multivibrator as shown below. I am getting only 38.7kHz at the output. I checked the values of resistors and capacitors on the board and it is fine. Kindly provide the root cause of this problem and solution available.

Best regards

Ajith

  • 0
    TI__Guru**** 164366 points

    Ajith,

    Your results that are 20% lower than expected. The reasons are as follows.
    1) D1 has a voltage drop that slows the charging rate.
    2) The NE555 has a propagation delay (see figure 8 in DS)

    The easiest fix is trial and error because the math gets complicated when all factors are considered.
    I suggest 12nF capacitor as first try.