STMicroelectronics 100 W transition-mode PFC pre-regulator with the L6563S EVL6563S-100W EVL6563S-100W Data Sheet
Product codes
EVL6563S-100W
Test results and significant waveforms
AN3065
22/33
Doc ID 16279 Rev 2
The event of an open loop is captured in
. We can notice the protection
intervention, latching the operation of the L6563S. As mentioned previously, to restart the
system the input power must be recycled.
system the input power must be recycled.
4.6
TBO (tracking boost option)
To use the TBO function on L6563S, a dedicated input of the multiplier is available on pin #6
(TBO). The function can be implemented by simply connecting a resistor (RT) between the
TBO pin and ground.
(TBO). The function can be implemented by simply connecting a resistor (RT) between the
TBO pin and ground.
Usually, in traditional PFC stages, the DC output voltage is regulated at a fixed value
(typically 400 V) but in some applications, it may be advantageous to regulate the PFC
output voltage with the "tracking boost" or "follower boost" approach. In this way the circuit
with the TBO function provides better efficiency and thanks to the lower differential voltage
across the boost inductor, the value of L2 can be reduced as compared to the same circuit
without the TBO function.
(typically 400 V) but in some applications, it may be advantageous to regulate the PFC
output voltage with the "tracking boost" or "follower boost" approach. In this way the circuit
with the TBO function provides better efficiency and thanks to the lower differential voltage
across the boost inductor, the value of L2 can be reduced as compared to the same circuit
without the TBO function.
The TBO pin presents a DC level equal to the peak of the MULT pin voltage and is
representative of the mains RMS voltage. The resistor defines a current, equal to
V(TBO)/RT, that is internally 1:1 mirrored and sunk from pin INV (pin 1) input of the error
amplifier. In this way, when the mains voltage increases, the voltage at the TBO pin
increases also as well as the current flowing through the resistor connected between TBO
and GND. Then a larger current will be sunk by the INV pin and the output voltage of the
PFC pre-regulator will be forced to go higher. Obviously, the output voltage will move in the
opposite direction if the input voltage decreases.
representative of the mains RMS voltage. The resistor defines a current, equal to
V(TBO)/RT, that is internally 1:1 mirrored and sunk from pin INV (pin 1) input of the error
amplifier. In this way, when the mains voltage increases, the voltage at the TBO pin
increases also as well as the current flowing through the resistor connected between TBO
and GND. Then a larger current will be sunk by the INV pin and the output voltage of the
PFC pre-regulator will be forced to go higher. Obviously, the output voltage will move in the
opposite direction if the input voltage decreases.
To avoid an undesired output voltage rise should the mains voltage exceed the maximum
specified value, the voltage at the TBO pin is clamped at 3 V. By properly selecting the
multiplier bias it is possible to set the maximum input voltage above which input-to-output
specified value, the voltage at the TBO pin is clamped at 3 V. By properly selecting the
multiplier bias it is possible to set the maximum input voltage above which input-to-output
Figure 29.
EVL6563S-100W TM PFC load
transient at 115 Vac, 60 Hz, full load
to no load
transient at 115 Vac, 60 Hz, full load
to no load
Figure 30.
EVL6563S-100W TM PFC open loop
at 115 Vac, 60 Hz, full load
at 115 Vac, 60 Hz, full load
CH1: PFC output voltage
CH2: PFC_OK (pin #7)
CH3: gate drive (pin #13)
CH4: Iout
CH1: PFC output voltage
CH2: Vcc (pin #14)
CH3: gate drive (pin #13)
CH4: PWM_LATCH (pin #8)