How to Choose a High-Reliability DC-DC Module Power Supply?

DC-DC module power supplies are increasingly being used in industries such as telecommunications, industrial automation, power control, rail transit, mining, and military applications. The modular design can effectively simplify customers’ circuit designs and enhance system reliability and maintenance efficiency. So, how can we improve the reliability of power systems based on DC-DC modules? This article provides a brief analysis and discussion on this topic.

1. Why are DC-DC module power supplies necessary?

DC-DC isolation module power supplies are primarily used in distributed power systems to achieve electrical isolation, reduce noise, perform voltage conversion, provide voltage regulation, and offer protection functions. The benefits of using DC-DC isolation module power supplies are as follows:

First, the modular power supply adopts an isolated design, which can effectively isolate the common-mode interference from the primary-side equipment and prevent it from affecting the system, ensuring stable operation of the load.

Second, different loads require different supply voltages—for example, control ICs need 5V, 3.3V, and 1.8V; operational amplifiers used for signal acquisition require ±15V; relays require 12V or 24V; and the bus voltage is typically 24V, so voltage conversion is necessary.

Third, during long-distance transmission, the bus voltage will experience line losses, resulting in a lower voltage at the PCB board level. However, the load requires a stable voltage; therefore, it is necessary to have a wide-voltage input and a regulated, stable output.

Fourth, the power supply must protect both the system’s load and itself from damage under abnormal conditions.

2. How to choose a highly reliable DC-DC module power supply?

Adopt a mature power topology

When designing power modules, prioritize the use of well-established power topologies. For example, for DC-DC power modules with a fixed-voltage input ranging from 1W to 2W, the Royer circuit is typically chosen; for wide-voltage-input series, the Flyback topology is often preferred, while some applications may opt for the Forward topology.

High efficiency across the entire load range

High efficiency means lower power loss and reduced temperature rise, which can significantly enhance reliability. In practical applications, power supplies typically adopt a certain degree of derating design—especially nowadays, when the power consumption of load ICs is becoming increasingly low. As a result, power supplies often operate under light-load conditions for most of the time. Therefore, high efficiency across the entire load range is a critically important parameter for the reliability of power supply systems—but it’s often overlooked by power supply manufacturers. To attract customers with appealing specifications in their technical manuals, most manufacturers tend to optimize full-load efficiency to a relatively high level, yet their efficiency drops significantly at loads ranging from 5% to 50%.

Taking the 15W DC-DC module power supply VRB2412LD-15WR2 as an example, the VRB2412LD-15WR2 exhibits an efficiency that is 15% higher than the industry average when operating at a light load of 10% under its rated input voltage of 24V, as shown in Figures 1 and 2.

Improving efficiency can also effectively reduce the temperature rise of the product’s enclosure; the VRB2412LD-15WR2 exhibits a temperature rise that is 13.8℃ lower when operating under actual load conditions.