1. Low Standby Power AC Adapter L6562 + L6668
90W 19V/4.7A AC-DC Converter Reference Design

2. 90W Adaptor General Features
Input Voltage range: 100 to 240Vac
Output Voltage and current: 19V/4.7A
Power Factor Correction: Above 0.98
Low Standby < 0.4W at no load condition
High Efficiency, typical 82% at low line full load
Latched OVP

3. L6562 - Power Factor Correction
Transition Mode Control
Very Precise Adjustable Output Over Voltage Protection
Ultra-Low Startup Current (<70mA)
ON-CHIP Filter ON Current Sense
Disable Function
1% internal reference voltage
-600mA/+800mA Totem Pole Gate Driver

4. L PWM Controller
Current Mode Controller with sophisticated standby feature
On board high voltage startup
Low quiescent current (<2mA)
Slope Compensation
Pulse-by-pulse & Hiccup-Mode OCP
Interface with PFC Controller
Disable Function (on/off control)
Latched Disable for OVP/OTP Function
Programmable soft start

5. L6668 – Standby Operation
The device operates in different modes depending on the converter’s load condition
1.) Fixed Frequency at heavy load
2.) Frequency-foldback at medium load
3.) Burst Mode Control with no or very light load.

6. L6668 + L6562 Operation This MOSFET has to withstand
high stress for short period.
Points to note:
PWM is powered up before PFC.
PFC is switched off during standby mode.
PWM MOSFET has to withstand high stress for a short period of time under low line, full load before bulk capacitor voltage build up!

7. L6668 -- Programmable Frequency Foldback

8. L6668 -- Load Dependent Operating Mode

9. L6668 -- Interface with PFC Controller

10. L6668 -- Converter Output in Short Circuit

11. 90W Demoboard Schematic

12. Demoboard Layout

13. PFC Inductor
Inductance 0.7mH

14. Main Transformer
Inductance 0.7mH

15. Demoboard Test Result – Power Factor

16. Demoboard Test Result – Standby power loss
No Load Power (mW)
Input Voltage (Vac)

17. Demoboard Test Result – Load Regulation
220Vac
100Vac
Output Voltage
Output Current

18. Demoboard Test Result -- Line Regulation
0A output current
5A output current
Output Voltage
Input AC Voltage

19. PFC Waveforms
At 110Vac
Ch.1 Current Waveform Ch2.: Bridge Rectifier output waveform
At 220Vac
Ch.1 Current Waveform Ch2.: Bridge Rectifier output waveform

20. Main Converter Vdrain Normal Operating Waveform
At 110Vac
At 220Vac

21. Main Converter Vdrain during Short Circuit Condition
At 110Vac
At 220Vac

22. Demoboard BOM Item Reference Part Description 1 Assembly Dwg. 2
Schematic 3
PC Board
PC Board,1-Layers,136mm x62mm 4
F101
3.15A/250V
fuse 5 RT
NTPA78R0LBMB0
Murata NTR 6 RV
G471
varistor 7
R101,R102
1.5M
resistor 8
R103
22K 9
R104
75K 10
R105
20ohm 11
R106,R107
750K 12
R108,R121
9.1K 13
R109
470ohm 14
R111
68K
3W resistor 15
R112
0ohm 16
R113,R123 1K 17
R114 4K

23. Demoboard BOM 18 R115 2.2K resistor 19 R116 150K 20 R117,R120 47K 2122
R119
82.5K 23
R122
10ohm 24
R124,R125,R126 2M 25
R127
12K 26
R128
5.6K 27
R201
30ohm
3W resistor 28
R202
0ohm 29
R203
2.4K 30
R204
15K 31
R205,R206,R207 1K 32
R208 33
CX101
0.22uF/275V
X2 capacitor 34 CY
2.2nF/400V
Murata DE1E3KX222M 35
C101
0.47uF/400V
Capacitor

24. Demoboard BOM 36 C102,C109,C113 10nF/50V Capacitor 37 C103 680nF/50V38
C104,C116
1uF/50V 39
C105,C110,C111
100nF/50V 40
C112
3.3nF/50V 41
C107
82uF/450V
电解电容 42
C108
100uF/35V 43
C115
56nF/50V 44
C117
22uF/35V 45
C201
1nF/1KV 46
C202,C203,C204
1000uF/35V 47
C205
220uF/35V 48
C206
330nF/50V 49
BR101
KBL810G
bridge rectifier 50
D101
STTH310S
rectifier 51
D102
P6KE250 52
D104
FR107 53
D201,D202
STPS20150CT

25. Demoboard BOM 54 Z101 20V zener diode 55 Z102 13V 56 Q101 STP12NM50
MOSFET 57
Q102
STP10NK70Z 58
Q103
3904
transistor 59
Q104
3906 60
Q201
ST TL431
voltage reference 61
COM101
400uH 共模 62
COM102
22mH 63
COM201
360uH 64
L101
22uH
差模色环电感 65
L201
10uH
差模磁棒 66
OPT
K817P6
opto-coupler 67
IC101
L6562D
PFC IC 68
IC102
L6668
PWM IC 69
TR1
PQ32/20
Transformer 70
TR2