The +18-V and –5-V rails are converted from an external 12-V bias signal. The following figures show the switching behaviors of these bias converters.

Figure 4-13 +18 V Boost Converter Switch Node at TP9, V_IN = 400 V and V_OUT = 400 V at 2 A (5 V/DIV, 200 ns/DIV, BWL = 800 MHz)

Figure 4-14 –5 V Inverting Buck-Boost Converter Switch Node at TP17, V_IN = 400 V and V_OUT = 400 V at 2 A (5 V/DIV, 200 ns/DIV, BWL = 800 MHz)