Problem with synchronous buck design

[Manjula]

Hello,

I am building a Synchronou Buck Converter with 12 V input and 1.5 V/60
A output,switching frequncy is 300 KHz. When I increase the input
voltage above 6 V, the input filter inductor starts making a high
pitched sound. Can anyone tell me the reason for this? Thank you.


Manjula

 

[Jim Stockton]

Hello,

I am building a Synchronou Buck Converter with 12 V input and 1.5 V/60
A output,switching frequncy is 300 KHz. When I increase the input
voltage above 6 V, the input filter inductor starts making a high
pitched sound. Can anyone tell me the reason for this? Thank you.

Manjula

Usually that is caused by magnetostriction of the core material but is
also a sign of loop instability in the audio range so that the sound
produced is in the audible range.
Good Luck
Jim Stockton

 

[Baphomet]

Hello,

I am building a Synchronou Buck Converter with 12 V input and 1.5 V/60
A output,switching frequncy is 300 KHz. When I increase the input
voltage above 6 V, the input filter inductor starts making a high
pitched sound. Can anyone tell me the reason for this? Thank you.


Manjula

Can you post the schematic on alt.binaries.schematics.electronic

 

[John Popelish]

Hello,

I am building a Synchronou Buck Converter with 12 V input and 1.5 V/60
A output,switching frequncy is 300 KHz. When I increase the input
voltage above 6 V, the input filter inductor starts making a high
pitched sound. Can anyone tell me the reason for this? Thank you.

Manjula

Your feedback loop is unstable and is ramping the duty cycle up and
down in the audio range. Most cores produce a bit of movement as
their magnetization is changed.