how much is high sawtooth in TL494 compared to input voltage

[darioklc]

TL494

Hi!
**broken link removed**
If I connect pins like that in this picture, how high voltage must I get into pin1 to get 50% duty cycle and how much to get 100%duty cycle. So basically, my question is how much is high sawtooth in TL494 which is compared to my input voltage?
frequency of that chip will we 20kHz and VCC from 7-20V.
Thanks!

 

[fsmyth]

Re: TL494

You need a bit of buffer on pin 3.

Look at the reference schematics at:
**broken link removed**

Quite a few are capable of a 50% duty cycle.

 

[darioklc]

Re: TL494

You need a bit of buffer on pin 3.

Look at the reference schematics at:
**broken link removed**

Quite a few are capable of a 50% duty cycle.

Nice schematics!
You see, I want to control my duty cycle only with my reference voltage. So my reference voltage would be compared to sawtooth voltage od TL494 like this:
**broken link removed**
but I dont know what is voltage od sawtooth in TL494.
I saw in some schematics that this kind of regulating duty cycle can be done if you ground all inputs of TL494 and get that reference voltage on pin3.

 

[ymq8328]

TL494 is not a good PWM control

I used the Tl497 one year ago.But the chip don't work good,maybe I make some mistake. later I find a new PWM control, at datasheetdir.com . It works. good luck.