Switching MOSFET @ Particular PWM give Constant Current or Constant Voltage ?

[asking]

Hi,

I am trying to Make a Charger and Discharger with Variable Voltage and Current Rates. But before that i need to clear the doubt i had. I want to know when i Switch MOSFET @ 10K PWM Frequency just in Buck Converter. Actually what changes ? and what remains constant ? if i need to maintain constant current passing through MOSFET how should i implement it ? and what if i want Constant Voltage Supply through MOSFET ? how should i implement that ?

Can anyone throw some light on my doubts.

Thanks.

 

[alexan_e]

The current and voltage are related, if your mosfet can't provide enough current then the voltage will drop.

The constant voltage vs constant current don't have to do with the mosfet or the feedback signal type (DC, PWM etc) but with the feedback circuit itself.
If the feedback circuit (we can call it a comparator too) checks the output for a constant current level then when it drops/rises it drives the mosfet accordingly to conduct more/less) in order to maintain the desired current level.
On the other hand if the feedback circuit checks for a constant voltage then it will try to maintain that constant voltage.

 

[asking]

tHANKS i got your point, you mean to say that i need to keep on checking current if its application of Constant Current Source, while on the same if its application of Constant voltage source i should Measure the Voltage and drive the mosfet accordingly.

Thanks for clearing doubt. Finally everything is dependent on V = I*R.

 

[alexan_e]

Yes, you need to implement a feedback that compares the output current or the output voltage with a preset value and based on this comparison drive the switching element that can be a transistor or a mosfet

 

[asking]

Wonderful Piece of information thanks.