Hi, thanks for you video @Aniccame, first of all, I am Brazilian and English is not my native language, I am sorry for any grammatical mistake. I have estimated the equation for dead time, consider: "Td" as the Dead Time "VI" as the Input voltage of your "VC" as the Capacitor voltage and Comparator negative input voltage. The equation would be: Td = -R.C.Ln((VI-VC)/VI) + Comparator propagation delay. The Comparator propagation delay of LM2901 is 300ns (300*10^-9) for a TTL input step (check pag 9, 7.11). In one of @Aniccame's circuits, he uses 5V as "VI”, 2.5V as VC, 1000 as R and (270pF)270*10^-12 as C, His estimated Td would be: Td = -1000*270*10^-12*Ln((5-2.5)/5) + 300*10^-9 Td = 187*10^-9 + 300*10^-9 Td = 487ns. He got 450ns, which is very close to the estimated value, the error could be explained by capacitor and resistor tolerances + propagation delays of the components. I hope this could be useful for someone.
Thanks for this video, and the simple circuits, but you need more than one IC . Have you tried a good old IC (TL494) which does the whole job and offers dead time control . There are lots of app. notes on this IC. This IC has two comparator op amps and a stable reference voltage pin.
instead of an op amp you could use a zener diode of a slightly greater ZENER VOLTAGE than the threshold voltage of the AND gate input. the zener diode can be connected in REVERSE BIAS so when the slow rising voltage from the RC setup reaches more than the zener voltage, the zener diode will start conducting and will give an output signal to the AND gate input
Can I use this circuit when I put 22kHz PWM signal as an input signal? If i can't, How can I change dead time? Can you let me know the equation of deadtime?
PWM will work. The equation of the deadtime has to do with the risetime of an RC circuit. I can't seem to find a live version of the document called AND8408-D from OnSemi that this was based on.
which part of circuit is controlling deadtime.i need dead time in microseconds.then which part I should change.is there any way to calculate components value for required deadtime.
R1 and C1. R2 and C2. The charging of the capacitors through the resistors creates a sloping waveform that provides a time delay so the comparator doesn't turn on as quickly. Increasing R and/or C will increase the delay. The calculation can be done by using an RC time constant calculator and determining at what point the voltage on the capacitor will equal (slightly exceed, really) the voltage set by the comparator's voltage divider.
I don't know about soft start, I'm sorry. I know old HP power supplies used SCRs and it is described here under the Open Control section: www.softstarter.org/how-does-soft-start-work-959233.html
I saw the link but the soft start that said is included in IC PWM controller , the duty cycle grow up slowly to avoid the inrush current (for ex in BUCK or BOOST converter) The IC PWM controller that i'm using ( more sheaper) does not have the soft start and i would like to create it
Hi, thanks for you video @Aniccame, first of all, I am Brazilian and English is not my native language, I am sorry for any grammatical mistake. I have estimated the equation for dead time, consider:
"Td" as the Dead Time
"VI" as the Input voltage of your
"VC" as the Capacitor voltage and Comparator negative input voltage.
The equation would be:
Td = -R.C.Ln((VI-VC)/VI) + Comparator propagation delay.
The Comparator propagation delay of LM2901 is 300ns (300*10^-9) for a TTL input step (check pag 9, 7.11). In one of @Aniccame's circuits, he uses 5V as "VI”, 2.5V as VC, 1000 as R and (270pF)270*10^-12 as C, His estimated Td would be:
Td = -1000*270*10^-12*Ln((5-2.5)/5) + 300*10^-9
Td = 187*10^-9 + 300*10^-9
Td = 487ns.
He got 450ns, which is very close to the estimated value, the error could be explained by capacitor and resistor tolerances + propagation delays of the components. I hope this could be useful for someone.
GOOOOD VID finally found what i was looking for TNX!
Thank you ,back to the work bench, just what I was looking for
Thanks for taking the time to share.
My pleasure!
thanks for posting this video i have been looking for a dead time generator. i am going to build this circuit.
Thanks for this video, and the simple circuits, but you need more than one IC . Have you tried a good old IC (TL494) which does the whole job and offers dead time control . There are lots of app. notes on this IC. This IC has two comparator op amps and a stable reference voltage pin.
instead of an op amp you could use a zener diode of a slightly greater ZENER VOLTAGE than the threshold voltage of the AND gate input. the zener diode can be connected in REVERSE BIAS so when the slow rising voltage from the RC setup reaches more than the zener voltage, the zener diode will start conducting and will give an output signal to the AND gate input
i like that idea
Hey whatis the formula that you used for Dead time calculation? Please let me know
Awesome!
just wanan say dude u just saved my ass thank you for this video
you're very welcome. are you making something cool?
Can I use this circuit when I put 22kHz PWM signal as an input signal? If i can't, How can I change dead time? Can you let me know the equation of deadtime?
PWM will work. The equation of the deadtime has to do with the risetime of an RC circuit. I can't seem to find a live version of the document called AND8408-D from OnSemi that this was based on.
can i use this circuit for making deadtime on PWM signal from arduino output with 50Hz frequency ?
Thank you!
which part of circuit is controlling deadtime.i need dead time in microseconds.then which part I should change.is there any way to calculate components value for required deadtime.
R1 and C1. R2 and C2. The charging of the capacitors through the resistors creates a sloping waveform that provides a time delay so the comparator doesn't turn on as quickly. Increasing R and/or C will increase the delay. The calculation can be done by using an RC time constant calculator and determining at what point the voltage on the capacitor will equal (slightly exceed, really) the voltage set by the comparator's voltage divider.
hi every one,
I should use IGBT in my circuit for a Buck converter.
how should i model it in LTspice?
I liked your video, i was looking for this ( i'm doing a synchronous buck conveter )
CAN YOU PLS MAKE A VIDEO ABOUT SOFT START ?
I don't know about soft start, I'm sorry. I know old HP power supplies used SCRs and it is described here under the Open Control section: www.softstarter.org/how-does-soft-start-work-959233.html
I saw the link but the soft start that said is included in IC PWM controller , the duty cycle grow up slowly
to avoid the inrush current (for ex in BUCK or BOOST converter)
The IC PWM controller that i'm using ( more sheaper) does not have the soft start and i would like to create it
I'm not sure. I can ask some friends who know much more than me if you could provide detailed requirements and your existing circuit.
Do you know if there is an equation to determine the reel dead time ?
i dont know what is the dead time i put on my synchronous buck ...
i try this on proteus but its not work TT