EVL6566A-75WADP STMicroelectronics, EVL6566A-75WADP Datasheet - Page 21

• Manufacturer Part Number: EVL6566A-75WADP
• Description: BOARD EVAL FOR L6566A
• Manufacturer: STMicroelectronics
• Type: Power Factor Correctionr

Specifications of EVL6566A-75WADP

• Main Purpose: AC/DC, Primary and Secondary Side with PFC
• Outputs And Type: 1, Isolated
• Power - Output: 75W
• Voltage - Output: 19V
• Current - Output: 4A
• Voltage - Input: 90 ~ 264VAC
• Frequency - Switching: 65kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6563, L6566A, TSM1014
• Input Voltage: 90 V to 264 V
• Output Voltage: 19 V
• Dimensions: 78 mm x 174 mm
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Regulator Topology: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L6563, L6566A
• Other names: 497-6449

L6563 - L6563A
6.4
THD optimizer circuit
The L6563/A 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 will result in both minimizing the time interval where energy transfer is lacking and fully
discharging the high-frequency filter capacitor after the bridge.
Figure 37 shows the internal block diagram of the THD optimizer circuit.
Figure 37. THD optimizer circuit
@ Vac1
@ Vac1
@ Vac2 > Vac1
@ Vac2 > Vac1
MULT
MULT
t
t
t
t
VFF
VFF
1 / V
1 / V
1 / V
GENERATOR
GENERATOR
GENERATOR
2
2
2
MULTIPLIER
MULTIPLIER
MULTIPLIER
OFFSET
OFFSET
OFFSET
COMP
COMP
t
t
+
+
+
+
t
t
comparator
comparator
Application information
to PWM
to PWM
t
t
t
t
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