Dynamic or transient loads on DC power supplies
A constant voltage output power supply should have a feedback loop in its design to continuously maintain a stable output voltage. Due to the fact that the feedback loop has a certain bandwidth, it limits the power supply's response to changes in load current. If the phase shift between the input and output of the feedback loop exceeds 180 degrees when the gain (UNITYGAIN) is 1, the power supply will exhibit instability, loss of control, and oscillation.
The load current during actual operation is also dynamically changing rather than constantly maintaining (such as hard disk, floppy drive, CPU or RAM operation, etc.), so dynamic load testing is extremely important for power supplies. Electronic loads can be used to simulate harsh load conditions during power supply operation, such as the rapid rise and fall of load current slopes, cycles, etc. If the power supply can maintain a stable output voltage under harsh load conditions without producing excessive or insufficient voltage, then this test is passed.
Power supply good/failure signal
Power Good Signal (PGS), abbreviated as PGS, is a signal sent by the power supply to the computer system. When the output voltage of the power supply stabilizes, it notifies the computer system to perform the startup program. The power failure signal (POWERFAIL) indicates that the output voltage has not yet reached or dropped beyond a certain normal operating condition. The above is usually represented by PGS signals and changes in logic. When the logic is "1" or "High", it indicates that the power is good, while when the logic is "0" or "Low", it indicates that the power has failed.
The good power supply time of the power supply is the time from the output voltage stabilizing to the PGS signal changing from "0" to "1", generally between 100ms and 200ms. The power supply failure time is the time from the PUS signal changing from "1" to "0" to the output voltage falling below the stable range, generally above 1ms.
