PWM signal with Dead-Time

221

02:17:54

This circuit turns 2 MOSFETs on and off alternately. There is a small "dead-time" which doesn't allow the 2 MOSFETs to be on simultaneously. This is achieved by slowing down the rise time of the pulse that switches on the MOSFET, but not the fall time. In this circuit, the dead time is around 4us. 

So what is "dead-time"? It's just a very short period of time in whicn all "switches" are off. Why dead time? In circuits such as synchronous DC-DC converters (keep your eyes open for this one. I'm working on it and will publish it soon), both switches cannot be on at the same time as it will short the power supply. Hence, a small dead time is required between the closing of one switch and the opening of the other to prevent a short.

EC has decided to plot the green waveform in the negative. Argh!

published 7 years ago

PrathikP

7 years ago

This may not be the best solution, but this is all that I could come up with

hurz

7 years ago

for class A driver you do not need dead time. Its getting intesting in case of a complement stage of N and PMOS as half bridge but as single mosfet. What you probably mean is, this circuit can be used as timing "driver" for a half bridge ?

PrathikP

7 years ago

The 2 MOSFETs in this circuit are not in half bridge, but I just wanted to make sure my signal works properly before implementing it in the full circuit (because it would be hard to troubleshoot when it's in the full circuit)

PrathikP

7 years ago

Yes. A driver signal for a sync. Buck converter is what this is. http://everycircuit.com/circuit/5523955348406272

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