• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 64 subscribers
  • Views 477 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TL494: Oscillator frequency

Oba
Genius 16485 points
Part Number: TL494

Hello,

 

My customer has a question for oscillator frequency of TL494.

 

They are using 12.2Kohm+-1% for RT and 0.1uF+-10% for CT and the actual oscillator frequency is about 1.15KHz.

But from the below figure on the datasheet, the oscillator frequency with12.2KOhm and 0.1uF should be around 0.9~1KHz.

So they feel actual frequency, 1.15KHz, is a littlie bit different from the figure, 0.9~1KHz.

Is this 1.15KHz reasonable value? Or anything wrong?

 

Regards,

Oba

  • +1
    TI__Mastermind 27625 points

    Hi Oba,

    The graph you are showing is on a log (y-axis), log (x-axis) and gives a fairly "linear" approximation but the actual F vs RT, CT relationships are non-linear. I would say that if the target frequency from the graph is 900 Hz<F< 1kHz and the actual measured frequency is 1.15 kHz, this is within 15% which is very good for a first pass. The graph gets the design in the "ballpark", the final target value can be adjusted on the bench. Also, when you are targeting frequencies at the extremes of the graph (such as 900 Hz-1 kHz), the degree of error is higher compared to midband frequency targets such as 10 kHz-100 kHz. 15% error near 1 kHz is excellent!

    Regards,

    Steve M