STMicroelectronics L6563H 100 W TM PFC demonstration board EVL6563H-100W EVL6563H-100W Data Sheet
Product codes
EVL6563H-100W
Test results and significant waveforms
AN3063
20/33
Doc ID 16261 Rev 3
4.4 Startup
operation
On the L6563H, the high-voltage startup function is implemented. The HVS (pin #9), is
directly connected to the DC bulk voltage and at startup, an internal high-voltage current
source charges C10 and C11 until the L6563H turn-on voltage threshold is reached, at
which point the high-voltage current source is automatically switched off. As the L6563H
starts switching it will be initially supplied by the V
directly connected to the DC bulk voltage and at startup, an internal high-voltage current
source charges C10 and C11 until the L6563H turn-on voltage threshold is reached, at
which point the high-voltage current source is automatically switched off. As the L6563H
starts switching it will be initially supplied by the V
CC
capacitor, and then the transformer
auxiliary winding will provide the voltage to power the IC. Because the L6563H integrated
HV startup circuit is turned off, it is not dissipative during normal operation. It has a
significant role in reducing power consumption when the power supply operates at light
load.
HV startup circuit is turned off, it is not dissipative during normal operation. It has a
significant role in reducing power consumption when the power supply operates at light
load.
In the following
and
the waveforms during the startup of the circuit at mains
plug-in are shown. We can notice that the Vcc voltage rises up to the turn-on threshold, and
the L6563H starts operating. 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 the peak value of the rectified
mains to the nominal value of the PFC output voltage. The good margin of the
compensation network allows a clean startup, without any large overshoot.
the L6563H starts operating. 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 the peak value of the rectified
mains to the nominal value of the PFC output voltage. The good margin of the
compensation network allows a clean startup, without any large overshoot.
4.5
PFC_OK pin and feedback failure (open loop) protection
During normal operation, the voltage control loop provides for the output voltage (Vout) of
the PFC pre-regulator close to its nominal value, set by the resistor ratio of the feedback
output divider. In the L6563H the PFC_OK pin has been dedicated to monitor the output
voltage with a separate resistor divider composed of R3, R6, R11 (high) and R15 (low), see
the PFC pre-regulator close to its nominal value, set by the resistor ratio of the feedback
output divider. In the L6563H the PFC_OK pin has been dedicated to monitor the output
voltage with a separate resistor divider composed of R3, R6, R11 (high) and R15 (low), see
. This divider is selected so that the voltage at the pin reaches 2.5 V if the output
Figure 27.
EVL6563H-100W startup at 90 Vac,
60 Hz, full load
60 Hz, full load
Figure 28.
EVL6533H-100W startup at 265 Vac,
50 Hz, full load
50 Hz, full load
CH1: PFC Output voltage
CH2: Vcc voltage (pin #16)
CH3: RUN (pin #12)
CH4: Gate drive (p in #15)
CH1: PFC output voltage
CH2: Vcc voltage (pin #16)
CH3: RUN (pin #12)
CH4: Gate drive (pin #15)