Feedback design problem in synchronous buck conveter.

[deepakchikane]

Dear all,

i have been fuzzed in the following problem.
i m been designing a buck converter. but i could not give the feedback of output to the controller.

if i try to give feedback to controller my pwm are getting low.that is not appearing (getting vanished)

i have attached the picture of projects

Kindly help me out..

 

[FlapJack]

This shows a block diagram with type II compensation.

https://www.intersil.com/en/product...single-output---buck-controllers/ISL6545.html

 

[BradtheRad]

Your converter is synchronous. It has a second switching device instead of a diode.

It will make the design easier (at the start, anyway) if you use the asynchronous type, the simpler type. Try changing Q2 to a diode.

 

[D.A.(Tony)Stewart]

Photos of layout, Schematic, parts list are all critical to design and problem solving along with waveform capture on scope and good test methods.

Choice of materials, wiring length, probe ground, inductor stray capacitance or SRF, dielectric losses, RdsON all are design variables.

What choices did you make?