High voltage, ICs

In this example, the error amp on the eontrol IC (a UC3843AP) is disabled by wiring the inputs of the error amp so that the output is guaranteed to be high. The values of R are not important (say 10K eaeh). The eompensation pin has a 1mA eurrent souree internally and has a high voltage of +4.5 V for the full output eondition. 

A variation on this method is ealled the shut-down on overcurrent eireuit shown in Figure 3-48. Here the start-up eireuit is a diserete, high-voltage, one-shot eireuit that is aetive only during the start-up sequenee, but turns eompletely off thereafter. If an overeurrent foldbaek eondition is experieneed, the IC and drive eireuits no longer have a voltage supply from whieh to draw eurrent. This... 

Once, while working as an Apps engineer at this maker of high-voltage Flyback monolithic switcher ICs, I happened to express concern about the way they were selecting the input bulk capacitors for their evaluation boards. To this day, in my opinion, they are making several misleading/erroneous recommendations to their customers via their eval boards. 

Asano, K., et al., High-Temperature Static and Dynamic Characteristics of 3.7 kV High Voltage 4H-SiCJBS Diode, Proc. of the 12th Inti. Conf. on Power Semiconductor Devices and ICs, May 22-25, 2000, pp. 97-100. 

Surprisingly, device eccentricities may on occasion play a part in defining the limits of r too. For example in Figure 2-8 we have presented the current limit plot of an integrated high-voltage flyback switcher IC called the Topswitch . On it we have superimposed a typical switch current waveform, just to make things a little clearer. 

The controller IC then failed and the high voltage/current damaged several components connected to the pins of the IC, including the optocoupler ... 

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