A switching regulator does for DC signals what a transformer does for AC signals; it enables the conversion of the voltage level. As the name suggests, this function is achieved by sampling and switching a series device on and off to achieve the desired DC voltage level.
While that may seem relatively simple and easy to understand at first, it should be noted that the slightest miscalculation can lead to disastrous results. Therefore, we must be very careful and cautious when it comes to choosing the frequency (i.e. the duty cycle) of the regulator.
The Effects of Changing the Duty Cycle of the Switching Regulator:
Here’s how the performance of the switching regulator varies as its duty cycle (or switching frequency is changed).
1. Noise Levels:
It goes without saying that the effect of noise should be as minimal as possible. Noise, whether conducted or radiated, adversely affects signal quality and also increases the likelihood of errors and faults.
That being said, adjusting the level of noise in the signal isn’t nearly as complicated as fine tuning the other factors mentioned on this list and that’s because system noise has an inverse relationship with the duty cycle. In other words, you can decrease the influence of noise by increasing the duty cycle of the switching regulator.
2. Overall Efficiency:
At the end of the day, no parameter matters more than the operational efficiency of a device. The same holds true for DC switching regulators as they’re often judged on their efficiency levels.
Unfortunately, this is where things get complicated as the overall efficiency of a switching regulator is inversely related to its switching frequency. In other words, we can increase the efficiency of the regulator by decreasing its switching frequency.
The problem becomes apparent when you compare the impact of noise and efficiency side by side. Noise decreases when the duty cycle increases but this causes the overall efficiency to fall. In other words, a compromise or a middle ground must be found between the two to ensure that the switching regulator operates as desired.
3. Form Factor:
If you’re working on an electrical circuit that has significant space constraints (for example if a switching regulator must be fitted on a PCB) then it makes sense to increase the frequency of the switching regulator.
Broadly speaking, the higher the duty cycle of the switching regulator, the lower space it requires on the board (as the sizes of capacitors and inductors involved significantly decreases).
4. Ripple:
Ripple or ripple factor is a little tricky to understand as its desired magnitude varies from application to application. In other words, for some applications we need to create a switching regulator which is highly resistant to ripples while in other cases the ripple factor needs to be lowered.
No matter what the desired value of the ripple factor may be, just know that its value decreases as the switching frequency increases.
And that concludes our list of the factors you need to consider when it comes to designing a switching regulator. We hope that this blog clears any confusion you may have had about the subject matter and that you can now create better electrical networks.
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