EVL6566B-65W STMicroelectronics, EVL6566B-65W Datasheet - Page 7

• Manufacturer Part Number: EVL6566B-65W
• Description: BOARD EVAL FOR L6566B
• Manufacturer: STMicroelectronics

Specifications of EVL6566B-65W

• Main Purpose: AC/DC, Primary Side
• Outputs And Type: 1, Isolated
• Power - Output: 65W
• Voltage - Output: 12V
• Current - Output: 5.4A
• Voltage - Input: 90 ~ 265VAC
• Regulator Topology: Flyback
• Frequency - Switching: 80kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6566B
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6452

APPLICATION NOTE
Open Loop Protection (OVP)
In figure 9 and 10 it is shown the circuit behaviour simulating an open loop condition by opening
R17. Once the voltage on ZCD pin connected to the transformer auxiliary winding by a divider rises
over its threshold, the L6566B stops switching. To prevent from unlatching the circuit by the Vcc
drop, the internal HV current source of the L6566B is periodically reactivated to keep the Vcc
voltage above the turn-off threshold. The IC consumption is reduced too. To resume the normal
operation the input mains has to be re-cycled.
In pictures 9 and 10 the output voltage during Open loop operation has been captured. As visible
comparing the two pictures, thanks to the L6566B internal circuitry, the output voltage value in this
condition is almost independent by the load.
Figure 9: EVAL6566B-65W
Open loop at 230Vac-50Hz – Full load
CH1:
CH2:
CH3:
Start up behaviour
In the pictures below, the start up behaviour is shown in two different load conditions. The output
voltage rising is monotonic and doesn’t show any overshoot
Figure 11: EVAL6566B-65W Start up behaviour
at 230Vac-50Hz – Full load
CH1:
CH2:
CH3:
Q101 Drain voltage
L6566B Vcc (pin #5)
VOUT
L6566B Soft Start (pin#14)
L6566B Vcc (pin #5)
VOUT
Figure 10: EVAL6566B-65W
Open loop at 230Vac-50Hz – No load
Figure 12: EVAL6566B-65W Start up behaviour
at 230Vac-50Hz – No load
CH2:
CH3:
CH1:
CH2:
CH3:
L6566B Vcc (pin #5)
VOUT
L6566B Vcc (pin #5)
VOUT
L6566B Soft Start (pin#14)
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