Solving PWM Issues with TL494 - Get 50% Duty Cycle

[kk116]

Hi,

I am trying to build an inverter and i am using Tl494 for my PWM, i am getting the right frequency but am not getting the 50% duty cycle. Can anyone suggest me any ideas on how to adjust the duty cycle for Tl494
Thanks.

Krishna

 

[kk116]

Thanks for the respond.
TL494 is a Texas Instruments PWM control IC. Here is the datasheet link.
http://focus.ti.com/docs/prod/folders/print/tl494.html
Thanks.

 

[berkeman]

Hi,

I am trying to build an inverter and i am using Tl494 for my PWM, i am getting the right frequency but am not getting the 50% duty cycle. Can anyone suggest me any ideas on how to adjust the duty cycle for Tl494
Thanks.

Krishna

Why are you looking for 50% duty cycle? The max in the datasheet is 45%, and the duty cycle would be dependent on ... Quiz Question -- dependent on what?

 

[kk116]

I will use MOSFETs and i will use PWM to turn on or off. I need the 50% duty cycle to turn the mosfets on and off for same period.
I am trying to make an inverter for 50 Hz. The example given in the data sheet gives the duty cycle of 45% but has max frequency. I want the PWM osc. frequency to be 50 Hz. And I AM NOT SURE IF PWM OSC. FREQ WILL BE MY MOSFETs OUTPOT FREQUENCY OR NOT?
Moreover, i was able to get the PWM to 50 Hz but my duty cycle was 10% and i tried increasing the reference voltage but still didn't help.

Thanks

 

[famousken]

The duty cycle can be adjusted by adjusting the voltage on the feedback pin(3). This is normally used for voltage regulation in a power supply.

 

[kk116]

Thanks again, I had tried that before but I had ref v to be 5v. I think it was a problem since my comparator triang wave had pk-pk of 2.6v I was able to vary now with ref v from 0-.7v. Thanks again for the information
Now I have to drive MOSTETs with this pwm signal. Can I get heads up on how to make MOSFETs switching to get AC out?

Thanks