The average of the MB CHG ISNS signal (on TP1) can be used to monitor the output current of the power supply. The following figures show the signal shape for varying output conditions.

Figure 4-15 V_IN = 400 V, V_OUT = 400 V, I_OUT = 2 A.
I_mean = 2.03 V (500 mV/DIV, 4 µs/DIV, BWL = 20 MHz)

Figure 4-16 V_IN = 400 V, V_OUT = 400 V, I_OUT = 500 mA.
I_mean = 511 mV (500 mV/DIV, 4 µs/DIV, BWL = 20 MHz)

Figure 4-17 V_IN = 400 V, V_OUT = 400 V, I_OUT = 100 mA.
I_mean = 107 mV (500 mV/DIV, 4 µs/DIV, BWL = 20 MHz)