[ Ссылка ]
CLICK ON "Active Current Limiter"
RTCA/DO-160 can require large capacitors to hold-up critical circuits during power interruption testing. DO-160 also requires the device stay under a certain inrush requirement. These requirements often lead designers to design a passive or active current limiter to limit the inrush to their holdup capacitance.
Shown in this video is a passive inrush limiting circuit that I have seen used many times. Though this circuit can work is supplemented with large enough decoupling and an adequate power line filter, it does not take advantage of the large capacitance for emissions purposes.
The voltage of the holdup capacitance will be a diode drop below the voltage at the load. This will work for power interruptions but may cause emissions issues during a low-frequency current demand. The hold-up capacitor cannot provide any power until the voltage on the power line dips. Fluctuation in voltage on the power lines can create an emissions failure.
Contrary to the passive inrush current limiter, the active current limiter will have the large holdup capacitance directly on the load. The capacitance will source power immediately to the load during a power interruption or a low/high frequency current demand.
