At this stage, there are many kinds of power modules in the sales market. The input working voltage, power, function and topology of different power products are different. Their characteristics are to distribute power for microprocessors, integrated circuit chips and other large digital or analog loads.
The output working voltage is slightly lower
The output working voltage of the switching power supply is too low, which will make the subsequent power supply circuit unable to operate normally. When the load suddenly expands in the microprocessor system, it will pull down the power distribution working voltage of the microprocessor, resulting in microprocessor calibration, which will severely crack down on the power supply circuit at the whole system level and lead to a chain reaction of one child falling wrong and the whole disk being destroyed. What are the reasons for the low output working voltage?
Multiple loads are connected in series in the output stage. After normal operation, a load requires a large amount of transient current, resulting in the instantaneous reduction of the working voltage, which affects other loads in series.
The output line is too long or too thin, resulting in excessive line loss, resulting in a large pressure drop between the lines. Finally, when the output working voltage of the power module reaches both sides of the real load, the working voltage is slightly lower.
The input filter inductance in the field power supply circuit of the control module is too large, resulting in the expansion of internal resistance and the improvement of current control. When the later stage load suddenly becomes heavier and heavier, the current supply is not available, resulting in a slightly lower working voltage on both sides of the load.
Solution
Connect a large capacitor at the output or switch to a higher power input switching power supply; Adjust the routing, expand the cross-sectional area of the conductor or reduce the length of the transmission line and reduce the internal resistance. If the power module has the function of trim adjustment, the output working voltage can be increased to offset the pressure drop caused by the line loss; Use the secondary pipe with small on-off pressure drop; Reduce the filter inductance value and reduce the internal resistance of the inductor.
High input operating voltage
Because the working voltage capacity design of electronic components inside some power modules is not enough, when the input working voltage is too high, the control module will be damaged or even damaged, which requires us to do some protection in the field. What common reasons are easy to lead to the high input working voltage?
When the input end of the power module is powered on by hot plug, its working voltage peak and surge current are high, and the control module resistant to pressure difference will be destroyed by instant thermal breakdown.
The working voltage impulse of the later stage distribution switching power supply leads to high input working voltage or dry deflection working voltage. Electromagnetic compatibility test is also easy to lead to high input working voltage, such as lightning surge and group single pulse.
Solution
Ensure that the output end is not less than 10% of the rated load. If the actual power supply circuit often has full load, connect a false load of 10% of the maximum power at the output end in parallel; Replace an input working voltage source with a reasonable and stable range. When there is dry and flexible working voltage, consider adding TVs tube or Zener at the input end, or adding EMC field power supply circuit.
