Datasheet
Table Of Contents
- Figure 1. Block diagram
- 1 Description
- 2 Maximum ratings
- 3 Pin connection
- 4 Electrical characteristics
- 5 Typical electrical performance
- Figure 3. IC consumption vs. VCC
- Figure 4. IC consumption vs. TJ
- Figure 5. VCC Zener voltage vs. TJ
- Figure 6. Startup and UVLO vs. TJ
- Figure 7. Feedback reference vs. TJ
- Figure 8. E/A output clamp levels vs. TJ
- Figure 9. UVLO saturation vs. TJ
- Figure 10. OVP levels vs. TJ
- Figure 11. Inductor saturation threshold vs. TJ
- Figure 12. Vcs clamp vs. TJ
- Figure 13. ZCD sink/source capability vs. TJ
- Figure 14. ZCD clamp level vs. TJ
- Figure 15. R discharge vs. TJ
- Figure 16. Line drop detection threshold vs. TJ
- Figure 17. VMULTpk - VVFF dropout vs. TJ
- Figure 18. PFC_OK threshold vs. TJ
- Figure 19. PFC_OK FFD threshold vs. TJ
- Figure 20. Multiplier characteristics at VFF = 1 V
- Figure 21. Multiplier characteristics at VFF = 3 V
- Figure 22. Multiplier gain vs. TJ
- Figure 23. Gate drive clamp vs. TJ
- Figure 24. Gate drive output saturation vs. TJ
- Figure 25. Delay to output vs. TJ
- Figure 26. Start-up timer period vs. TJ
- 6 Application information
- 7 Application examples and ideas
- Figure 34. Demonstration board EVL6564-100W, wide-range mains: electrical schematic
- Figure 35. L6564 100W TM PFC: compliance to EN61000-3-2 standard
- Figure 36. L6564 100W TM PFC: compliance to JEITA-MITI standard
- Figure 37. L6564 100 W TM PFC: input current waveform at 230 - 50 Hz - 100 W load
- Figure 38. L6564 100W TM PFC: input current waveform at 100 V - 50 Hz - 100 W load
- 8 Package mechanical data
- 9 Order codes
- 10 Revision history
DocID16202 Rev 5 23/33
L6564 Application information
33
Figure 31. THD optimization: standard TM PFC controller (left side) and L6564 (right side)
Essentially, the circuit artificially increases the ON-time of the power switch with a positive
offset added to the output of the multiplier in the proximity of the line voltage zero-crossings.
This offset is reduced as the instantaneous line voltage increases, so that it becomes
negligible as the line voltage moves toward the top of the sinusoid. Furthermore the offset is
modulated by the voltage on the V
FF
pin (see Section 6.3: Voltage feed-forward) so as to
have little offset at low line, where energy transfer at zero crossings is typically quite good,
and
a larger offset at high line where the energy transfer gets worse.
The effect of the circuit is shown in
Figure 31, where the key waveforms of a standard TM
PFC controller are compared to those of this chip.
To take maximum benefit from the THD optimizer circuit, the high-frequency filter capacitor
after the bridge rectifier should be minimized, compatibly with EMI filtering needs. A large
capacitance, in fact, introduces a conduction dead-angle of the AC input current in itself -
even with an ideal energy transfer by the PFC preregulator - thus reducing the effectiveness
of the optimizer circuit.
6.5 Inductor saturation detection
Boost inductor's hard saturation may be a fatal event for a PFC preregulator: the current up-
slope becomes so large (50 - 100 times steeper, see
Figure 32) that during the current
sense propagation delay the current may reach abnormally high values. The voltage drop
caused by this abnormal current on the sense resistor reduces the gate-to-source voltage,
so that the MOSFET may work in the active region and dissipate a huge amount of power,
which leads to a catastrophic failure after few switching cycles.
Imains
Vdrain
Imains
Vdrain
In p ut c urre nt Input current
M OS FET's d rai n vol t a ge
M OSFE T's dra i n vol t ag e
Rectified mains voltage Rectified mains voltage
Input current
Input current