Improving Isolated Power Modules with the MID06W0505A Series

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Introduction

Power modules form a core part of power electronics applications. In particular, micro-power power modules are widely used to power various signal isolator applications, such as RS485, CAN, and RS232. Industry applications — such as industrial automation, electric vehicle battery management systems (BMS), and charging piles — continue to increase standards for safety, power density, and reliability.

To improve power density and ease of design in the power electronics industry, MPS launched an isolated DC/DC power module family, the MID06W0505A series (including the MID06W0505A-3, MID06W0505A-2, EV1W0505A-Y-00A, and EV06W0505A-Y-00B), which are available in an SOIC-16 (10.3mmx10.3mmx2.5mm), chip-scale package (see Figure 1).

Figure 1: MID06W0505A Power Module

Traditional power modules are typically assembled by PCBs, capacitors, resistors, transformers, and ICs, and then encased in plastic shells. MPS uses a chip-level SOIC-16 package that is convenient for soldering, significantly reduces board space, improves reliability, and provides excellent performance.

This article will explore the advantages of the MID06W0505A-3.

Package and Reliability

Figure 2 shows a traditional module.

Figure 2: Traditional Power Module

With a traditional module, the potting glue is prone to aging because air bubbles can be mixed in during the potting process. Bubbles can be removed by placing the module in a box with a low atmospheric pressure to release the mixed air, but there is still a margin for error, so aging can still occur. This can lead to potting glue cracks and shell bulging. Even if most of the bubbles are extracted, the internal bubbles repeatedly expand and shrink during use, which also ages the potting glue. Aged potting glue significantly impacts the device by reducing the module’s reliability. It can also lead to primary and secondary insulation failures, which can be dangerous for users.

In addition, traditional power modules generally operate in a narrow -40°C to +85°C temperature range. The plug-in package is easily deformed, the pins are not able to achieve automatic welding, and the efficiency is low. Traditional modules can also be difficult to implement in space-constrained applications due to their height.

The MID06W0505A-3 addresses the shortcomings of traditional power modules with the following features:

High pressure is used to encapsulate the plastic. This chip-level packaging system prevents bubbles from being created while improving reliability and pressure resistance
-40°C to +125°C operating temperature range
Convenient, ultra-thin 2.5mm SOICW-16 package for SMT automation improves production efficiency and achieves a very thin profile to meet stringent height requirements

Magnetic Field Immunity

When a product is exposed to a strong magnetic field, it can experience communication anomalies or even be burnt. These issues are often due to radiated or conducted magnetic interference.

Figure 3 shows an experiment in which magnets were placed above a module to create interference.

Figure 3: Interference Experiment Using Magnets

Figure 4 shows the stable output of the MID06W0505A-3 while a magnet is above the power module.

Figure 4: Stable Output of the MID06W0505A-3

These results contrast with traditional power modules, which can experience severe oscillations. For a traditional solution, a 5V output could overshoot to 7.8V, which could damage sensitive circuitry that is downstream from the power module (see Figure 5).

Figure 5: Output of a Traditional Module

The abnormal output is due to open-loop control. When subjected to external interference, the module’s internal circuit cannot be adjusted by close-loop regulation, and the output voltage (V_OUT) fails to regulate. The MID06W0505A-3 uses advanced isolation feedback technology to provide real-time feedback on the external interference, which achieves closed-loop control and stabilizes V_OUT.

Output Voltage Adjustments

In some cases with more stringent requirements for voltage regulation, a traditional power supply module has an unregulated V_OUT that fluctuates significantly with the input voltage (V_IN) and load. In particular, when V_IN is at a maximum and there is no load, V_OUT fluctuates and rises to a substantial level. In this scenario, it is recommended to connect a dummy load at 10% of the rated load.

V_OUT regulation can affect the subsequent stage circuit’s system stability, which can result in relatively high static power consumption. The MID06W0505A-3 features internal closed-loop control, a stable V_OUT, no minimum load requirements, and a stable output while the static power consumption is low.

Figure 6 shows a comparison between a traditional module’s load regulation and the MID06W0505A-3’s load regulation.

Figure 6: Load Regulation Comparison

Figure 7 shows a comparison between a traditional module’s linear adjustment rate and the MID06W0505A-3’s linear adjustment rate.

Figure 7: Linear Adjustment Rate Comparison

The MID06W0505A-3 is evidently more robust than traditional modules. Its unique features and leading performance indicators include:

4.5V to 5.5V V_IN range
5V regulated V_OUT with excellent dynamic performance
Typical 0.2% load regulation and 0.1% line regulation
Up to 0.6W output rated power (1W optional)
Supports continuous short-circuit protection (SCP), and over-temperature protection (OTP)
3KV_DC isolation voltage
Meets CISPR32 Class B EMI test
Certification according to IEC62368-1

Figure 8 shows the concise peripheral circuit of the MID06W0505A-3.

Figure 8: MID06W0505A-3 Peripheral Circuit

Conclusion

MPS is committed to introducing isolated power modules that meet the growing demands for safety, power density, and reliability. In this article, we discussed how the MID06W0505A-3 overcomes the limitations of traditional power modules, in addition to addressing challenges such as magnetic interference and fluctuating V_OUT. These are all key considerations for powering various signal isolator and industry applications.