EVL6563H-250W STMicroelectronics, EVL6563H-250W Datasheet - Page 28

• Manufacturer Part Number: EVL6563H-250W
• Description: EVAL BOARD FOR L6563
• Manufacturer: STMicroelectronics
• Type: Power Factor Correctionr

Specifications of EVL6563H-250W

• Main Purpose: Power Management, Power Factor Correction
• Embedded: No
• Utilized Ic / Part: L6563
• Product: Power Management Modules
• Supply Current: 5 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L6563H
• Other names: 497-10378

Application information
6.4
Figure 41. THD optimizer circuit
28/49
THD optimizer circuit
The L6563H is provided with a special circuit that reduces the conduction dead-angle
occurring to the AC input current near the zero-crossings of the line voltage (crossover
distortion). In this way the THD (total harmonic distortion) of the current is considerably
reduced.
A major cause of this distortion is the inability of the system to transfer energy effectively
when the instantaneous line voltage is very low. This effect is magnified by the high-
frequency filter capacitor placed after the bridge rectifier, which retains some residual
voltage that causes the diodes of the bridge rectifier to be reverse-biased and the input
current flow to temporarily stop.
To overcome this issue the device forces the PFC pre-regulator to process more energy
near the line voltage zero-crossings as compared to that commanded by the control loop.
This results in both minimizing the time interval where energy transfer is lacking and fully
discharging the high-frequency filter capacitor after the bridge.
Figure 41
shows the internal block diagram of the THD optimizer circuit.
Doc ID 16047 Rev 3
L6563H