Post Date : Mar 09, 2023 / Last updated : Apr 06, 2023
The frequency of switching of the switching power supply, such as DC/DC or AC/DC, is called the oscillation frequency.
Generally, the IC shows the switching frequency when switching is performed in a loaded state.
Generally, if the oscillation frequency is high, there are the advantages of component miniaturization and fast response speed, but the disadvantages are the efficiency decreases or the EMI noise increases. For this reason, the optimum oscillation frequency must be selected to match the application and purpose.
| Item | Effect of High Frequency Oscillation Frequency |
|---|---|
| Efficiency | Efficiency declines |
| Component size/mounted surface area | Miniaturization |
| Component cost | Inexpensive |
| Transient response characteristic | Improved responsiveness |
| Ripple voltage | Dependent on peripheral components/constant |
| Noise | EMI noise worsens |
In addition, for PFM control and PFM/PWM control, the switching frequency during light loads becomes lower than the oscillation frequency, so care needs to be taken when implementing noise countermeasures.