The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> High-Power Design >> How the switch mode power supply regulate input voltage?
https://designers-guide.org/forum/YaBB.pl?num=1467913861

Message started by ArtBen on Jul 7^th, 2016, 10:51am

Title: How the switch mode power supply regulate input voltage?
Post by ArtBen on Jul 7^th, 2016, 10:51am

Hello everyone, I have a question about SMPC.

As we know that no matter buck, boost or buck-boost, we use a feedback to control either frequency or duty cycle to maintain the output while the load changes.

But how does the switch mode stabilise the output while the input voltage changes? Because from the equation between input and output, the relationship is based on duty cycle. In low droplet regulator, the output is related to reference, reference is independent to temperature and input voltage, so that the output is only dependent to reference and the ratio of the resistors. But from switch mode, there is no relationship shown that the output is independent to the input.

Thank you!

Title: Re: How the switch mode power supply regulate input voltage?
Post by sheldon on Oct 29^th, 2016, 5:02am

ArtBen,

Not clear what you are talking about. Do you mean the variations
in the line voltage or the reference voltage of the compensator op-amp?
The response of an LDO and a switching regulator to both types of
variations is analogous. Can you clarify your question?

Sheldon