Building a Current sensing circuit using DC-DC converter
Good Afternoon guys,
As mentioned at the subject, i really have to build the circuit for my class project..the problem is i dont know where to start and what components should i buy..maybe someone has the practical circuit i could refer to or is there any reference from the internet i should take a look? i really have to start building it right now..thanx
Pyose, Malaysia
Have your instructor give a class in How to Write a Specification.
You mean current sensing /for/ a DC-DC converter? There are many ways, for example if you want to measure the switching current then a simple toroidal ferrite core with a single winding (lots of turns) would do. Feed the current carrying wire through the center of the toroid, place a small resistor accross the toroid winding, and there you go, output voltage is proportional to the current in the wire that goes through the toroid.
Example coils
If you want to sense DC current, a hall effect sensor could do. If it doesn't have to be galvanically isolated current sensing, then you could also use a series resistor ("real resistor" or just a thin ning slab of copper, circuit board trace, etc) which is placed e.g. on the ground lead. Then measure the voltage drop accross the resistance, typically is some millivolts (U=R*I...)
If you want to see how to use the current sensing in a DC-DC converter, check the application notes for various PWM controllers, they usually have example circuits that show current sensing, too.
For example
TL494, LM3524, UC3864, ...
- Jan
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