hi all,
Ive been using a TL494 for a timer for around 100khz. Though ive had problems controlling the deadtime on the IC. The deadtime is linked with the frequency so if you alter the capacitor to get other freqeuncy ranges it alters the deadtime which is bad. I can just alter the resisor but it doesnt give me a good range.
Ive tried a 555 and added in a seperate deadtime circuit which works great. but the problem here is the deadtime chops the wave so I have to start with a wave such as 40:60 to get a wave like 45:45 output. The problem then is I have to alter 2 resistors to change the frequency, which then changes the duty cycle which is a problem which then leeds to the deadtime being wrong.
Has anyone got and ideas on a way around all these problems ? There is a nice IC the UC3844 which looks like a basic version of the TL494 though I cant get this to work. Is the any Ic's where I can set the deadtime seperate from the frequency ? I want to power a H-bridge so the on/off switch times much have a small dealy (deadtime) though witht he TL494 its hard to keep everything how it should be. The end result with the 494 is like a 42:42 cycle which is close to what I want though I can't alter the frequency much without it upsetting the deadtime.
can anyone suggest a IC or circuit which would allow me to change each spec without it upsetting another one ?
thanks chris