The actual circuit is built as Figure 1-1 to verify the simulations. C=4.7 μF, R=2 Ω, the output of the LDO is 6 V, and the input PWM signal is 50 V_pp at 20 kHz with a 50% duty cycle. AMC1311-Q1 is the selected isolated amplifier and TPS7A4101 is the selected LDO for the wide input range.

The start-up time is around 260 μs, and the steady-state output is 5.1 V with 29.7 mV ripple, matching reasonably well with the Figure 2-3. The discrepancy between simulation and hardware is due to equipment current limitations, which are not accounted for in an designed for simulation.

The ripple from the bootstrap power supply had minimal impact on the performance of AMC1311-Q1 when compared to the performance with a clean power supply. The clean signal was generated using a transformer and an LDO from the low-side power rail. This transformer power supply is approximately twice the size of the bootstrap power supply and much more expensive than the bootstrap, due to the cost of the transformer. If the ripple was too high, the bootstrap power supply can also be smoothed with simple RC filters. This can add minimal size and cost to the circuit.