AN4248 datasheet(37/46 Pages) STMICROELECTRONICS

Part #	AN4248

Description	60 W PSU design details for water purifier system

PDF	46 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

Logo

37 / 46 page

DocID024214 Rev 1

37/46

AN4248

Short-circuit test

In Figure 34 , we can observe the behavior of the VCC voltage as described above. In

Figure 35, the waveforms are triggered in different time scale, where single switching pulses

are spaced with 150 us.

Figure 36 & 37 displays more clearly the single pulse timing and peak values of drain-

source voltage with leakage spike overshoot and peak drain current values. Triggered at

different levels corresponding to different Ton instants. Looking to figure 22, maximum drain

current is limited to 2.7 A peak approx and there is no saturation effect observed in

transformer.

The overall operation is safe and average input power from the mains drops to negligible

values.

Figure 32. Hold up test CH1: load current 2.4 A max; CH4: AC Input 230 V

AN4248 Datasheet(PDF) 37 Page - STMicroelectronics