Operating waveforms

AN2840

8/19

2.1

No-load waveforms

During no-load conditions, the circuit operates in burst mode. Thanks to the VIPER17HN

high voltage startup generator, low current consumption, low VDD voltage at no-load and

the low consumption of the TSM1052, the input power is less than 100 mW over the entire

input voltage range. Figure 9 and Figure 10 show the main waveforms in this condition.

During no-load operation, the burst frequency is around 1 kHz. However, due to the very low

peak current, acoustic noise is not generated on the board.

Figure 9.

load condition

Figure 10.

load condition

CH1: VIPER17HN FB pin (yellow trace)

CH1: VIPER17HN FB pin (yellow trace)

CH2: VIPER17HN VDD pin (cyan trace)

CH2: VIPER17HN VDD pin (cyan trace)

CH3: VIPER17HN drain pin (purple trace)

CH3: VIPER17HN drain pin (purple trace)

CH4: Output voltage (green)

CH4: Output voltage (green)