EVL6563H-100W View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
EVL6563H-100W Datasheet PDF : 31 Pages
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AN3118
Test results and significant waveforms
4.4
Startup operation
In the L6563H, a high voltage startup function is implemented. The HVS pin (#9), is directly
connected after the rectifier bridge. At startup, an internal high voltage current source is
activated and charges C8 and C9 until the L6563H turn-on voltage threshold is reached,
then the high voltage current source is automatically turned off. Once the L6563H starts
switching it is initially supplied by the Vcc capacitor, and then the transformer auxiliary
winding provides the voltage to power the IC. Because the L6563H integrated HV startup
circuit is turned off it is not dissipative during the normal operation, therefore it has a
significant role to reduce the power consumption when the power supply operates at light
load.
In Figure 29 and 30, the waveforms during the startup of the circuit at mains plug-in are
shown. Notice that the Vcc voltage rises up to the turn-on threshold, and the L6563H starts
the operation. Because the high voltage current source delivers a constant current, the
wake-up time is almost independent to the input mains voltage.
As mentioned previously, for a short time the energy is supplied by the Vcc capacitor, and
then the auxiliary winding with the charge pump circuit takes over. At the same time, the
output voltage rises from peak value of the rectified mains to the nominal value of the PFC
output voltage. The good phase margin of the compensation network allows a clean startup,
without any large overshoot.
Figure 29. EVL6563H-250W TM PFC: startup at Figure 30. EVL6563H-250W TM PFC: startup at
90 Vac - 60 Hz - full load
265 Vac - 50 Hz - full load
CH1: PFC output voltage
CH2: Vcc voltage (pin #16)
CH3: RUN (pin #12)
CH4: gate drive (pin #15)
CH1: PFC output voltage
CH2: Vcc voltage (pin #16)
CH3: RUN (pin #12)
CH4: gate drive (pin #15)
Doc ID 16847 Rev 2
19/31
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