Feedback loop control scheme type and basic difference between them?

Lighting Solutions
1

What are the different feedback loop control scheme are available and what are differences between them and to choose with which control scheme we should go-ahead? Like I know there are three types of control method - 1.) Peak current mode control 2.) Voltage mode control 3.) Hysteresis (ripple) mode control , but some time I find fixed frequency and constant on time control method (COT), I am bit confused about these terms - fixed frequency and COT . Can you please explain what is fixed frequency and COT control, in which category they fall and what are their generel application and how to recognise that it’s a fixed or COT control method??

2

Hi,
In terms of identifying COT control converters, for constant on time control, the control scheme consists of a comparator and a latch. In COT, it does not have a clock. Since latch is used, ON-Time is controlled while off time is variable.

Here is some more helpful links to aid in your studying/research -

Advantages of Constant-On-Time Control in DC/DC Converters | Article | MPS (monolithicpower.com)
Constant On-Time (COT) Control for FPGA High-Current Power Supplies (monolithicpower.com)

Best,
Nouman

3

Hi Nouman,
Thanks for sharing the document link , it really helped me in understanding the difference between the traditional control scheme Vs COT.
I have one question, does these control scheme (current or voltage mode control or COT control scheme) have any impact over the input AC current waveform (sinusoidal).
Also could you please share me the design guide of Boost Converter.

4

Hi Rishi,
Apologies on delayed response,
It depends, you can influence the ripple based on your freq/dutycyle and sizing of components surrounding the device.

You may start by choosing a certain boost converter device and familiarize with operation through datasheet. For example, here is one:
MP3431 | 21A, 16Vout High Efficiency Full-Integrated Synchronous High Power Boost Converter with Programmable Input Current Limit | MPS (monolithicpower.com)

You may also use the following to quickly check your understanding of waveforms by changing certain parameters and observing how it affects output operation.
DC DC Designer Online - Design Tools - Design (monolithicpower.com)

Best,
Nouman