Based on DIODES AP63200 low EMI medical display power supply solution

Hedy · Dasenic Jan 08,2025 28

All the elements listed such as medical, industrial, power tools and home appliances office equipment are very clear that electromagnetic interference (EMI) is the most important to a large extent. According to experience, as the operating frequency of the switch-mode converter increases, it becomes more difficult to suppress EMI. One suggestion is to reduce the need for suppression by designing components that generate less EMI. Similarly, EMI is a phenomenon that causes one electron to be affected by another device that is generating an electromagnetic field, that is, the stray properties in the RF (RF) favorite effect. At the system level, it is easy to know how much interference a product will generate, or how local interference will affect its own subsystem. We can start by selecting components that generate low EMI, which can greatly help overcome related design challenges. Low EMI becomes increasingly important when designing buck converters.

To this end, Diodes Incorporated has developed a series of low EMI converters that allow engineers to reduce the amount of EMI generated by their designs on switch-mode power conversion designs. By using more efficient switching devices, heat dissipation can also be reduced, and more compact devices can be developed. Low EMI buck converters are ideal for many applications, from network systems to power tools, laser printers, medical, industrial power supplies and 12V/24V power access power supplies, as well as consumer electronics supplies that require efficient converters for FPGAs, DSPs and ASICs. Low EMI buck converters are also suitable for home audio systems, game consoles, white goods and small appliances, flat-panel TVs/monitors and set-top boxes.

Dahl Technology's AP63200 For 2A synchronous buck converters, the input voltage range is 3.8V to 32V, supports 5V, 12V and 24V power inputs, and can withstand surge inputs of 40V for 400ms. Designed to provide instantaneous EMI performance and ultra-low quiescent current. Easy to use through hot current mode control, production is minimized. External component count. High-side 125mΩ and low-side 68mΩ MOSFETs are also integrated to support efficient step-down DC-DC conversion. The entire product line includes features that help minimize EMI when designing a switch-mode PSU. These include a spread spectrum (Frequency Spread Spectrum) of ±6% of the switching frequency, which reduces EMI by allowing the emitted energy to stay at any frequency during any significant pause. They also have a low-frequency driver scheme that resists ringing of the switch node without sacrificing the MOSFET turn-on and turn-off time, which also eliminates high-frequency radiated EMI noise caused by MOSFET switching.

Saving energy is a social consensus. For ordinary people, if the conversion efficiency of household appliances is higher, the energy saved over a long period of time will be considerable. Therefore, the power consumption voltage of the IC itself is also a key point to improve power consumption. The AP6320X series has an ultra-low 22uA quiescent current, up to 80% efficiency at light load 1mA, up to 88% efficiency at light load 5mA, adjustable low voltage lock point (UVLO) for increased design flexibility, and optimized pin arrangement (Pin 1. The AP63203 and AP63205 units in particular are fixed buck output converters with the best design in terms of EMI reduction, because the simpler PCB layout design reduces the number of external components required and guarantees a short current loop on the PCB, which creates a high probability of EMI problems. Fixed 3.3V and 5V output options further reduce the number of external components. Obviously, by understanding the root cause, the best solution can be designed to reduce the EMI of the switching power supply.