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TLC555: How to generate 21.5 KHz Square wave , duty cycle 50%?

dong andy
Prodigy 205 points
Part Number: TLC555
Other Parts Discussed in Thread: DRV8871, LMC555

Dear all,

 My project need a motor driver and I saw the DRV8871 EVM. It's good for my project. But there are some parameters to be modify. 

My questions:

1, The following schematic shows freq = 25KHz, How to calculate?

2, How to generate freq = 21.5KHz wave? Just change R2?

3, The Pin 7 (DISCH) is square wave output pin?

Thanks 

  • 0
    TI__Guru**** 165146 points

    Dong,

    1)  The diodes and potentiometer complicate the formula based on R3 and C2 values.

    2) No, change R3 or better yet, C2

    3) Yes it is. Pin 7 sinks current and R2 is pull up resistor for VOH.

    I suggest using  50% example from LMC555 data sheet.

    Rc = 100k, C = 330pF