Datasheet

L6566B List of figures
5/51
List of figures
Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 2. Typical system block diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3. Pin connection (through top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. Multi-mode operation with QR option active . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 5. High-voltage start-up generator: internal schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 6. Timing diagram: normal power-up and power-down sequences . . . . . . . . . . . . . . . . . . . . 19
Figure 7. Timing diagram showing short-circuit behavior (SS pin clamped at 5V). . . . . . . . . . . . . . . 20
Figure 8. Zero current detection block, triggering block, oscillator block and related logic . . . . . . . . 20
Figure 9. Drain ringing cycle skipping as the load is gradually reduced . . . . . . . . . . . . . . . . . . . . . . 22
Figure 10. Operation of ZCD, triggering and oscillator blocks (QR option active) . . . . . . . . . . . . . . . . 23
Figure 11. Load-dependent operating modes: timing diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 12. Addition of an offset to the current sense lowers the burst-mode operation threshold. . . . 25
Figure 13. Adaptive UVLO block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 14. Possible feedback configurations that can be used with the L6566B . . . . . . . . . . . . . . . . . 26
Figure 15. Externally controlled burst-mode operation by driving pin COMP: timing diagram. . . . . . . 27
Figure 16. Typical power capability change vs. input voltage in QR flyback converters . . . . . . . . . . . 28
Figure 17. Left: Overcurrent setpoint vs. VFF voltage; right: Line Feedforward function block . . . . . . 29
Figure 18. Hiccup-mode OCP: timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 19. Frequency modulation circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 20. Operation after latched disable activation: timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 21. Soft-start pin operation under different operating conditions and settings . . . . . . . . . . . . . 34
Figure 22. OVP Function: internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 23. OVP function: timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 24. Maximum allowed duty cycle vs. switching frequency for correct OVP detection. . . . . . . . 37
Figure 25. Brownout protection: internal block diagram and timing diagram . . . . . . . . . . . . . . . . . . . . 38
Figure 26. Voltage sensing techniques to implement brownout protection with the L6566B . . . . . . . . 39
Figure 27. Slope compensation waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 28. Typical low-cost application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 29. Typical full-feature application schematic (QR operation) . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 30. Typical full-feature application schematic (FF operation) . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 31. Frequency foldback at light load (FF operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 32. Latched shutdown upon mains overvoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46