Dodgecobra
New Member
I have a relatively good background in electronics and would like to build a DC to
DC converter that takes in 12v and outputs the following: 3v,4.5v,9v,12v,19v [50w max. with a max current of 5A @ voltages below 12]. I know this would best fall under SMPS. I have been able to exactly know what diode and inductor I need, switching frequency, ripple ratio and compensational counter measures against various losses but havent been able to find the info that will give me what optimum output capacitor and switching mosfet (that will be controlled by a PWM signal) that I require. I have chosen to go with Continous conduction mode and I have gone through switching power supplies A to Z by Maniktala according to the relevant chapters and the best I can get is its voltage rating should be at least 20 - 50 % above max output voltage. My best guess for the capacitance would be sth like CR=t where C is the capacitance and R is the load resistance which makes t a value that should be far greater than the switch's off time . As for the switching mosfet all I think is it has to brave 5A average current all the time. What capacitance and mosfet should I work with? How do I get it by calculation?
DC converter that takes in 12v and outputs the following: 3v,4.5v,9v,12v,19v [50w max. with a max current of 5A @ voltages below 12]. I know this would best fall under SMPS. I have been able to exactly know what diode and inductor I need, switching frequency, ripple ratio and compensational counter measures against various losses but havent been able to find the info that will give me what optimum output capacitor and switching mosfet (that will be controlled by a PWM signal) that I require. I have chosen to go with Continous conduction mode and I have gone through switching power supplies A to Z by Maniktala according to the relevant chapters and the best I can get is its voltage rating should be at least 20 - 50 % above max output voltage. My best guess for the capacitance would be sth like CR=t where C is the capacitance and R is the load resistance which makes t a value that should be far greater than the switch's off time . As for the switching mosfet all I think is it has to brave 5A average current all the time. What capacitance and mosfet should I work with? How do I get it by calculation?