There is a bootstrap gate drive circuit for a inverter that I take the project of a graduate student as a reference and it works. But there are a few things that I don't understand in this circuit.
Like ;
-Why does the PWM signal come from the cathode to the anode?
-Why is a capacitor placed between the cathode and the anode?
-Why 12V is given externally to the anode? or
( Doesn't the opto coupler work without biasing the Anode? )
Also i will send another picture below wich includes 2 pre-bias supplies like the picture above.
He got the same things , only the difference is that they give 5V instead of 12V.
the driver section is taken by EG8010+TLP250.
It differs to the first one:
* Now there is no capacitor beween A nd C of the LED. It is between pin2 and GND. Mind the junction dot.
* It seems to be a low side driver and a high side driver
* low side driver pin5 is connected to GND
* high side driver pin5 is connected to the half bridge
* LED power supply now is 5V.
* maybe others...
Now to your questions.
-Why does the PWM signal come from the cathode to the anode?
the input of the optocoupler is a LED. It needs current to flow, it needs some power.
It is very basic knowledge that any LED will need both pins connected to be able to work.
I want to explain the reason by giving an example ,
when the PWM signals are applied, a voltage of 12V comes already to the anode of the IC.
In addition, I could not understand why it was directly powered by 12V with a pre-biased supply.
I mean , can't i just feed the opto - driver with the amplitude of the pwm signal?
I want to explain the reason by giving an example ,
when the PWM signals are applied, a voltage of 12V comes already to the anode of the IC.
In addition, I could not understand why it was directly powered by 12V with a pre-biased supply.
I mean , can't i just feed the opto - driver with the amplitude of the pwm signal?