The power module, due to its modular design and high reliability, has been widely used in industrial communication, medical, power, and other fields. During the application process, some failure issues may arise, which can lead to the system failing to start or even burning out the circuit. So how can we quickly locate and resolve these failures?
The role of the power module is to supply power to microcontrollers, integrated circuits, digital signal processors, analog circuits, and other digital or analog loads. Although the reliability of the power module is relatively high, failures can still occur during use, mainly categorized into two types: parameter abnormalities and usage abnormalities. The following will analyze common parameter abnormal failure issues of the power module and provide corresponding solutions. Some of these failures you may have encountered before.
1. Input Voltage Too High
This refers to the input parameter abnormality of the power module—input voltage being too high. This type of anomaly can lead to the system not functioning properly, or worse, burning out the circuit. What are the common causes of high input voltage?
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The output terminal is floating or has no load;
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The load on the output terminal is too light, less than 10% of the rated load;
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The input voltage is too high or there is interference voltage.
To address this type of issue, you can adjust the load on the output terminal or adjust the input voltage range, as follows:
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Ensure the output terminal is not less than 10% of the rated load. If there will be a no-load condition in actual circuit operation, connect a dummy load with a rated power of 10% in parallel at the output terminal;
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Replace with a reasonable input voltage range. If there is interference voltage, consider adding a TVS diode or voltage regulator at the input terminal.
2. Output Voltage Too Low
This refers to the output parameter abnormality of the power module—output voltage being too low. This can lead to the entire system not functioning normally. For example, in a microcontroller system, if the load suddenly increases, it can pull down the supply voltage to the microcontroller, easily causing a reset. Moreover, if the power module operates for a long time under low input voltage conditions, the lifespan of the circuit can be greatly compromised. Therefore, the issue of low output voltage should not be overlooked. What are the common causes of low output voltage?
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The input voltage is low or insufficient power;
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The output wiring is too long or too thin, causing excessive line loss;
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The reverse connection diode at the input has too high a voltage drop;
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The input filter inductor is too large.
To address this type of issue, you can improve it by adjusting the power supply or replacing the corresponding peripheral circuit, as follows:
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Increase the voltage or switch to a higher power input power supply;
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Adjust the wiring to increase the cross-sectional area of the wire or shorten the wire length to reduce internal resistance;
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Replace with a diode that has a lower conduction voltage drop;
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Reduce the value of the filter inductor or lower the internal resistance of the inductor.
3. Output Noise Too High
This refers to the output parameter abnormality of the power module—output ripple noise being too high. It is well known that noise is a key indicator of the quality of a power module. The design layout of the module in the application circuit can also affect output noise. What are the common causes of high output ripple noise?
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The power module is too close to noise-sensitive components in the main circuit;
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The power input terminal of noise-sensitive components in the main circuit is not connected to a decoupling capacitor;
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In multi-channel systems, differential frequency interference occurs between the power modules of each single output;
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Improper handling of the ground wire.
The ZDS2024 oscilloscope tests a power module with significant noise interference issues, as shown:
To address this type of issue, you can improve it by isolating the module from noise-generating devices or using decoupling capacitors in the main circuit, as follows:
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Keep the power module as far away as possible from noise-sensitive components in the main circuit or isolate the module from noise-sensitive components;
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Connect a 0.1μF decoupling capacitor at the power input terminal of noise-sensitive components (e.g., A/D, D/A, or MCU, etc.);
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Use a multi-output power module instead of several single-output modules to eliminate differential frequency interference;
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Use a star grounding method to reduce the ground loop area.
4. Poor Voltage Resistance
This refers to the performance parameter abnormality of the power module—poor voltage resistance. Generally, the voltage resistance value of isolated power modules can reach several kilovolts, but in application or testing, it may not meet this standard. What factors can significantly reduce its voltage resistance capability?
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The voltage tester may experience startup overshoot;
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The selected module’s isolation voltage value is insufficient;
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Repeated use of reflow soldering or hot air guns during maintenance.
The method for testing the isolation voltage of the power module using a voltage tester is as follows:
To address this type of issue, improvements can be made through standardized testing and proper usage, as follows:
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Gradually increase the voltage during the voltage resistance test;
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Select a power module with a higher voltage resistance value;
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When soldering the power module, choose an appropriate temperature to avoid repeated soldering, which can damage the power module.
5. Choose High-Quality Isolated Power Modules to Reduce Circuit Design Risks
ZLG Zhiyuan Electronics independently researches and produces isolated power modules, which have a wide input voltage range and isolation of 1000VDC, 1500VDC, 3000VDC across multiple series, with various packaging forms compatible with international standards such as SIP, DIP, etc. Meanwhile, ZLG Zhiyuan Electronics, based on rich experience in power supply design and applications, can provide users with professional reference for power peripheral application circuit design, enhancing product reliability.
ZLG Zhiyuan Electronics power modules, with high efficiency, wide input voltage range, compact size, high reliability, shock resistance, good isolation characteristics, and wide temperature range, are suitable for board-level power supply applications and are widely used in power, industrial automation, communications, medical, transportation, building automation, instrumentation, and automotive electronics, among many other fields.
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