# input power sharing and with power limiting

According to this document which talks about how to do the power-sharing and power limits, these three figures are the power limit circuit, and I have three questions I am not sure how to solve.   1. I know how to calculate every circuit output gain, but I don't know how this power limit works, I mean why do need to detect the current and amplified the current (Figure 5) and sum it up with input voltage.
2. What does Feed-forward voltage mean?
3. I do not understand in figure 7, why this is called power limit circuit.

I read this document and these three questions I am still confused, hope someone can give some advice, and I will be very appreciative.

• There’s some amplification and filtering due to the capacitor in the feedback circuit. It’s a POWER (as in Volts times Amps) monitoring circuit. Wikipedia can explain feedforward. Jul 16, 2021 at 23:09
• @Kartman I do not quite understand how this circuit work, I do not understand why I need to detect the input voltage.
– EEC
Jul 17, 2021 at 3:03
• how else are you going to measure power without measuring the voltage? Power = Volts times Amps. thus you need to measure current and voltage. Jul 17, 2021 at 6:24
• @Kartman Yes, I know P=V*I, but in this circuit, it sums up the voltage and current not multiply. and how do I know how much gain I need?
– EEC
Jul 17, 2021 at 7:07