What are the common faults of DCDC power modules?

At present, different suppliers have launched a variety of different power modules on the market, and different products have different input voltages, output powers, functions, and topological structures. The characteristic of the power module is that it can provide power for application-specific integrated circuit (ASIC), digital signal processor (DSP), microprocessor, memory, field programmable gate array (FPGA) and other digital or analog loads. Although the reliability of the power supply module is relatively high, it may fail sometimes. Below we summarize for everyoneDcdc power moduleSeveral common faults.

1. The output voltage of the module decreases during use;

2. The module stops working;

3. The output voltage of the module is too high;

4. The module input is short-circuited;

5. The output current of the module is too large.

The failure of the first two DCDC power modules generally does not bring great danger, and can be detected and alarmed by the fault diagnosis circuit.

The third failure mode is more dangerous. It can burn the application circuit. Overvoltage protection is generally achieved through an overvoltage protection circuit. In addition, it can also be achieved by adding a Zener diode at the output. When designing, choose the parameters of the diode reasonably to prevent the change of the voltage stabilization point due to different temperatures. Some modules have their own overvoltage protection. Generally speaking, modules below 25W have no overvoltage protection function, and modules above 25W are designed with overvoltage protection circuits. The overvoltage protection point is generally designed to be 135%-145% of the rated voltage. In the detailed design, it is necessary to confirm whether the module has these functions, so as to avoid repeated design.

The fourth type will lead to input overcurrent and burn out the printed circuit board in severe cases. Generally, it can be protected by selecting a suitable fuse at the input end. The fuse is generally arranged near the input end of the power module when wiring. The purpose of this design is to reduce the lead inductance of the input line and avoid the overvoltage caused by the lead inductance when the fuse is blown.

The fifth type of DCDC power module failure can be achieved by selecting a power module with over-current protection. General power modules have over-current protection functions. This type of module can be realized by detecting the current of the primary or secondary side of the converter. But there is a certain loss of efficiency. When selecting a voltage module, it is not that the larger the power rating, the better. If the derating is too large, when the user board is short-circuited, due to the transmission voltage drop, the output current is not enough to realize the module overcurrent, which may cause the chip to overheat or even be damaged.