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TINA/Spice: PWM

Sneha Agarwal
Prodigy 110 points
Other Parts Discussed in Thread: TINA-TI

Tool/software: TINA-TI or Spice Models

HI, I want to sweep my duty cycle of pwm in two or three steps. Initial at 5% then 20% then 90% with time. for example for first 5ms it remains 5%, then for 5ms,it comes to 20% and so on. How can i design this in tina if i dont want to use a timer?

  • 0
    TI__Mastermind 39210 points
    Sneha,

    You can use a current source to charge a capacitor and a switch in parallel. This will give you a ramp voltage whose frequency can tuned to frequency of your switching signal.

    Next you can compare this ramp voltage with a fixed DC voltage. The magnitude of the DC voltage should be such that when it intersects with the ramp, it gives you 5% duty cycle for the 1st 5ms. After 5ms, change the DC voltage to a magnitude such that it now gives you 20% duty cycle and so on.

    You may need to understand how to use controlled sources (and the controlled source wizard) to implement this. Please refer to the video training series below if you have not already.