STMicroelectronics EVAL BOARD FOR L6563 EVL6563H-250W EVL6563H-250W Data Sheet

Doc ID 16047 Rev 3

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In table 1 it is possible to find a summary of all of the above mentioned working conditions 
that cause the device to stop operating.

 shows the internal schematic of the high-voltage start-up generator (HV 

generator). It is made up of a high-voltage N-channel FET, whose gate is biased by a 15 M

Ω 

resistor, with a temperature-compensated current generator connected to its source.

The HV generator is physically located on a separate chip, made with BCD off-line 
technology able to withstand 700 V, controlled by a low-voltage chip, where all of the control 
functions reside.

With reference to the timing diagram of 

, when power is first applied to the 

converter the voltage on the bulk capacitor (Vin) builds up and, at about 80 V, the HV 
generator is enabled to operate (HV_EN is pulled high) so that it draws about 1 mA. This 
current, minus the device's consumption, charges the bypass capacitor connected from pin 
Vcc (16) to ground and makes its voltage rise almost linearly. 

 

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