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All colleagues unite and focus their efforts to write a new chapter of developmentSwitching power adapters have four modulation methods.
所属分类： Industry News
发布时间：2020-06-15
Regarding the four modulation methods used in switch-mode power adapters, this is something that probably not many people are familiar with. Next, let’s take a look together with a Shenzhen power adapter manufacturer at what these four modulation methods are:
1. Pulse Density Modulation Type
Abbreviated as PDM, or Pulse Density Modulation, this technique is characterized by a constant pulse width, with voltage regulation achieved by varying the pulse count. It employs zero-voltage switching, which can significantly reduce power‑switching losses.
2. Pulse Width Modulation Type
Abbreviated as PWM, or pulse-width modulation, this technique is characterized by a constant switching period. By varying the pulse width to adjust the duty cycle, it achieves voltage regulation. At its core lies the PWM controller. Pulse‑width‑modulated switching power supplies are among the most widely used; they offer a broad range of duty‑cycle adjustment and can be synchronized with the main system’s clock.
3. Hybrid Modulation Type
It is a combination of modes ⑴ and ⑵. Both the switching period and the pulse width are variable and adjustable. It incorporates both a PWM controller and a PFM controller.
4. Pulse Frequency Modulation Type
Abbreviated as PFM, or pulse‑frequency modulation, this technique features a constant pulse width and adjusts the duty cycle by varying the switching frequency to achieve voltage regulation. At its core is the PFM controller. Pulse‑frequency‑modulated switching power supplies are particularly well suited for portable devices, as they can reduce the control IC’s quiescent current even under low‑duty‑cycle, low‑frequency conditions.
From the above four modulation methods, we can see that,
Switching power supply There are two main modulation methods: pulse-width modulation (PWM) and frequency modulation. Pulse-width modulation adjusts the output voltage (or power) by varying the duty cycle—the ratio of the on-time (Ton) to the waveform period. It should be noted that PWM controllers can be implemented as standalone integrated circuits, or they can be integrated into switch-mode regulators or monolithic switching power supplies. Switch-mode regulators belong to the category of DC–DC converters, whereas switching power supplies typically fall under AC–DC converters.