buck inductor current measurement

[niks]

Hi,

What is the correct method to measure inductor current in synchronous buck regulator citcuit?

thanks in advance

niks

 

[Davood Amerion]

I think you can use one of CT (Current Transformer) or small resistor, in seri with your inductor

 

[A.Anand Srinivasan]

usage of CT(Current transformer) is a better choice because inductor is a reactive and surge related component and in a switching regulator this phenomenon is used... so the usage of resistor would introduce power constraints....

 

[wky]

Use a current probe

 

[niks]

i have added sense resistor before inductor. I tried probing across it but i am not able to get expected waveform.

 

[A.Anand Srinivasan]

what is the problem which you are facing with the waveform.... can you please post your circuit and the waveforms.....

so that we can understand your problem better....

 

[niks]

Attaching my circuit. This is 12V to 5V/100mA buck regulator. Actually i would like to measure if my circuit current is limited to 100mA or not. So please help me to measure inductor current.

Q1 not poppulated.

 

[A.Anand Srinivasan]

i want the waveform you got and how much it differed from the expected waveform.... also what resistor value you used and the instrument used to obtain the waveform....

 

[gevy]

Useful link about current sense

 

[rfzheng]

you can sense the IR drop of the PMOS transistor, and this voltage could be converted by a V/I converter to obtain the actual inductor current.