1. The input voltage is too high
The input voltage of the power module is too high, which will cause the system to not work properly at the least, and the circuit will be burned.
Causes of excessive input voltage:
(1) The output end is suspended or unloaded
(2) The output terminal load is too light, lighter than 10% of the rated load
(3) The input voltage is too high or the interference voltage is
Solution: You can adjust the load at the output terminal or adjust the input voltage range. For example: l Make sure that the output end is not less than 10% of the rated load. If there is no load during actual circuit operation, connect a fake load with 10% of the rated power to the output end. l Replace an input voltage of a reasonable range. When there is an interfering voltage, consider adding a TVS tube or a voltage regulator tube at the input end.
2. The output voltage is too low
If the output voltage of the power module is too low, it may cause the overall system to not work properly. For example, in a microcontroller system, the load suddenly increases, which will lower the supply voltage of the microcontroller, which may easily cause reset. Moreover, if the power supply operates at low voltage for a long time, the life of the circuit will be greatly damaged.
Reasons for the low output voltage:
(1) The input voltage is low or the power is insufficient
(2) The output line is too long or too thin, causing excessive line loss
(3) The voltage drop of the anti-reverse diode at the input end is too large
(4) The input filter inductance is too large
Solution: It can be improved by adjusting the power supply or replacing the corresponding peripheral circuit. For example: adjust the voltage higher or replace the input power supply with a larger power, adjust the wiring, increase the cross-sectional area of the conductor or shorten the length of the conductor, reduce the internal resistance, and replace the diode with a small conductor voltage drop to reduce the filter inductor value or reduce the internal resistance of the inductor.
3. The output ripple noise is too high
Reasons for excessive output ripple noise:
(1) The distance between the power supply module and the main circuit noise-sensitive component is too close
(2) The decoupling capacitor is not connected at the power input end of the noise-sensitive component of the main circuit.
(3) Differential frequency interference occurs between the power modules with single outputs in a multi-channel system
(4) The ground wire treatment is unreasonable
Solution: It can be improved by isolating the module from the noise device or using decoupling capacitors in the main circuit. For example, isolate the power module as far away from the main circuit noise-sensitive components or modules as much as possible from the main circuit noise-sensitive components, connect a 0.1μF decoupling capacitor at the power input end of the main circuit noise-sensitive components (such as A/D, D/A or MCU, etc.), and use a multi-output power module to replace multiple single-output modules to eliminate differential frequency interference, and use a remote point grounding to reduce the ground loop area.
4. Poor voltage withstand power supply
The withstand voltage value of the power module is generally as high as several thousand volts, but it may not meet the index during application or testing.
Reasons for reducing pressure resistance:
(1) The voltage withstand voltage tester has an overshoot on the power supply
(2) The isolation voltage value of the selected module is not enough
(3) Reflow soldering and hot air guns are used multiple times during maintenance
Solution: It can be improved through standardized testing and standardized use. For example: during voltage withstand voltage test, select modules with higher voltage withstand voltage value, and select appropriate temperature when welding modules to avoid repeated welding and damage to the module.
5. Difficulty in starting the power module
The reason why the power module cannot be started or the startup is bad:
(1) Excessive capacitor is too large
(2) Capacitive load is too large
(3) The load current is too large
(4) The input power supply is not enough
Solution: It can be improved by adjusting the capacitance at the output and load or adjusting the power at the input. For example: l The external capacitor is too large, and it is charged to the power module for a long time when it is started, making it difficult to start. You need to select a suitable capacitive load. When the capacitive load is too large, you must first connect a suitable inductor in series. Too heavy output load will cause an extended startup time. Select a suitable load and replace it with a high-power power supply.
6. The power module has severe heat
Causes of excessive fever:
(1) The linear power supply module is used
(2) Load overcurrent
(3) The load is too small, if the load power is less than 10% of the output power of the module power, it may cause the module to generate heat and low efficiency.
(4) The ambient temperature is too high or the heat dissipation is poor
Solution: It can be improved by optimizing the external environment or by adjusting the load. For example: when using linear power supply, add a heat sink to increase the load of the power module, ensure no less than 10% of the rated load, reduce the ambient temperature, and maintain good heat dissipation.
7. The power module is damaged faster
Causes of faster damage:
(1) The output load is too light and its reliability is reduced, resulting in a reduction in reliability.
(2) The output terminal capacitor is too large and causes damage during startup of the module.
(3) The input voltage is too high for a long time and causes damage to the switch tube at the input end of the module.
Solution: It can be improved by changing the output load, capacitance or changing the appropriate input voltage. For example: make sure that the output end has no less than 10% of the rated load. If there is no load during actual circuit operation, connect a fake load with 10% of the rated power to the output end, select a capacitor that complies with the product manual and the appropriate input voltage.
8. The power module burns quickly after power is turned on
Reasons for rapid burnout after power on:
(1) The polarity of the input voltage is reversed
(2) The input voltage is much higher than the nominal voltage
(3) The polarity capacitor at the output end is reversed
(4) The output circuit is prone to short circuit or the external load has a large current at the moment of power-on
Solution: You need to recheck the circuit for corresponding optimization or adjustment of voltage. For example: before wiring, please check or add anti-reverse protection circuit, select the appropriate input voltage, check the polarity of the capacitor before powering on, ensure correctness, and add short circuit protection at the output end of the power module.