AN-PS0072-EVAL-2QR1765G-18W5V-V10 -20120521-small size low profile

Application Note, V1.0, 21 May 2012
A pp l i c at i on N ot e
AN- EVAL-2QR1765G-18W
18W 5V S mall Si ze Low P rofile E valuati on
Board with Quasi-Resonant CoolSET®
ICE2QR1765G
Power Management & Supply
N e v e r
s t o p
t h i n k i n g .
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2012 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
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conditions or characteristics. With respect to any examples or hints given herein, any typical
values stated herein and/or any information regarding the application of the device,
Infineon Technologies hereby disclaims any and all warranties and liabilities of any kind,
including without limitation, warranties of non-infringement of intellectual property rights
of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please
contact the nearest Infineon Technologies Office (www.infineon.com).
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on the types in question, please contact the nearest Infineon Technologies Office.
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or other persons may be endangered.
18W 5V small size low profile demo board using ICE2QR1765G
Revision History:
Previous Version:
Page
21 May 2012
V1.0
none
Subjects (major changes since last revision)
®
18W 5V Small Size Low Profile Evaluation Board with Quasi-Resonant CooLSET ICE2QR1765G
License to Infineon Technologies Asia Pacific Pte Ltd
AN-PS0072
Kok Siu Kam Eric
[email protected]
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EVAL-2QR1765G-18W
Table of Contents
1
Content ............................................................................................................... 5
2
Evaluation Board ............................................................................................... 5
3
List of Features .................................................................................................. 6
4
Technical Specifications ................................................................................... 6
5
Circuit Description............................................................................................. 6
5.1
Mains Input and Rectification..................................................................................................6
5.2
Integrated MOSFET and PWM Control ....................................................................................6
5.3
Snubber Network .....................................................................................................................6
5.4
Output Stage ............................................................................................................................6
5.5
Feedback Loop.........................................................................................................................7
6
Circuit Operation ............................................................................................... 7
6.1
Startup Operation.....................................................................................................................7
6.2
Normal Mode Operation...........................................................................................................7
6.3
Primary side peak current control...........................................................................................7
6.4
Digital Frequency Reduction ...................................................................................................7
6.5
Burst Mode Operation..............................................................................................................7
7
Protection Features ........................................................................................... 8
7.1
Vcc under voltage and over voltage protection......................................................................8
7.2
Foldback point protection .......................................................................................................8
7.3
Open loop/over load protection...............................................................................................8
7.4
Adjustable output overvoltage protection ..............................................................................8
7.5
Short winding protection .........................................................................................................8
7.6
Auto restart for over temperature protection..........................................................................8
8
Circuit diagram .................................................................................................. 9
8.1
PCB Top layer ........................................................................................................................10
8.2
PCB Bottom Layer .................................................................................................................11
9
Component List ............................................................................................... 12
10
Transformer Construction .............................................................................. 14
11
Test Results ..................................................................................................... 15
11.1
Efficiency and standby performance ....................................................................................15
11.2
Line and load regulation ........................................................................................................18
11.3
Vds and Vcs ...........................................................................................................................18
11.4
EMI test results ......................................................................................................................19
12
Waveforms and Scope Plots........................................................................... 21
12.1
Startup at Full Load................................................................................................................21
12.2
Zero Crossing Point During Normal Operation.....................................................................21
12.3
Load Transient Response......................................................................................................22
12.4
Burst Mode Operation............................................................................................................22
12.5
Protection Mode.....................................................................................................................23
13
References ....................................................................................................... 23
Application Note
4
21 May 2012
EVAL-2QR1765G-18W
1
Content
This application note is a description of a small size low profile 18W switching mode power supply evaluation
board designed in a quasi resonant flyback converter topology using ICE2QR1765G Quasi-resonant
®
CoolSET .The target application of ICE2QR1765G are for set-top box, portable game controller, DVD player,
®
netbook adapter and auxiliary power supply for LCD TV, etc. With the CoolMOS integrated in this IC, it
greatly simplifies the design and layout of the PCB. Due to valley switching, the turn on voltage is reduced
and this offers higher conversion efficiency comparing to hard-switching flyback converter. With the DCM
mode control, the reverse recovery problem of secondary rectify diode is relieved. And for its natural
frequency jittering with line voltage, the EMI performance is better. Infineon’s digital frequency reduction
technology enables a quasi-resonant operation till very low load. As a result, the system efficiency, over the
entire load range, is significantly improved compared to conventional free running quasi resonant converter
implemented with only maximum switching frequency limitation at light load. In addition, numerous
adjustable protection functions have been implemented in ICE2QR1765G to protect the system and
customize the IC for the chosen application. In case of failure modes, like open control-loop/over load, output
overvoltage, and transformer short winding, the device switches into Auto Restart Mode or Latch-off Mode.
By means of the cycle-by-cycle peak current limitation plus foldback point correction, the dimension of the
transformer and current rating of the secondary diode can both be optimized.Thus, a cost effective solution
can be easily achieved.
2
Evaluation Board
Figure 1-EVAL-2QR1765G-18W
Application Note
5
21 May 2012
EVAL-2QR1765G-18W
3
List of Features
Industry first IC in DSO16/12 package with 18W maximum output power
®
650V avalanche rugged CoolMOS with built in depletion startup cell
Quasi-resonant operation
Digital frequency reduction with decreasing load
Cycle-by-cycle peak current limitation with foldback point correction
Built-in digital soft-start
Direct current sensing with internal Leading Edge Blanking Time
VCC under voltage protection: IC stop operation, recover with softstart
VCC over voltage protection: IC stop operation, recover with softstart
Openloop/Overload protection: Auto Restart
Output overvoltage protection: Latch-off with adjustable threshold
Short-winding protection: Latch-off
Over temperature protection: Autorestart
4
Technical Specifications
Input voltage
Input frequency
Output voltage and current
Output power
Efficiency
Standby power
Minimum switching frequency at full load,
minimum input voltage
Size (WxLxH)
5
85Vac~265Vac
50Hz, 60Hz
5V 3.6A
18W
>80% at full load
<[email protected] load
40kHz
3
46x115x15 mm
Circuit Description
5.1
Mains Input and Rectification
The AC line input side comprises the input fuse F1 as overcurrent protection. The X2 capacitor CX1, and
common mode choke L1 form a main filter to minimize the feedback of RFI into the main supply. After the
bridge rectifier BD1, together with a smoothing capacitor EC1 and EC2, it provides a voltage of 100VDC to
380 VDC depending on mains input voltage. A 5.0Ω NTC resistor is in series with input to limit the initial peak
inrush current whenever the power supply is switched on while the EC1 and EC2 are fully discharged.
5.2
Integrated MOSFET and PWM Control
ICE2QR1765G is integrated of a power CoolMOS and a quasi-resonant controller which greatly simplifies
the circuit layout and reduces the cost of PCB. The PWM switch-on is determined by the zero-crossing input
signal and the value of the up/down counter. The PWM switch-off is determined by the feedback signal VFB and
the current sensing signal VCS. ICE2QR1765G also performs all necessary protection functions in flyback
converters. Details about the information mentioned above are illustrated in the product datasheet.
5.3
Snubber Network
A primary clamper/snubber network R2A, R2B, C1 and D1 dissipate the energy of the leakage inductance
and suppress ringing on the SMPS transformer. In addition the snubber resistor can be used with a larger
one to reduce the snubber loss.
5.4
Output Stage
On the secondary side, 5V output, the power is coupled out via a dual schottky diode D3. The capacitors
EC4、EC5、EC6 and EC7 provide energy buffering followed by the L-C filters L2, EC8、EC9 and C6、C7
Application Note
6
21 May 2012
EVAL-2QR1765G-18W
to reduce the output ripple and prevent interference between SMPS switching frequency and line frequency
considerably. Storage capacitors EC4、EC5、EC6 and EC7 are designed to have a very low internal
resistance (ESR). This is to minimize the output voltage ripple caused by the triangular current.
5.5
Feedback Loop
For feedback, the output is sensed by the voltage divider of R13 and R12 and compared to TL431 internal
reference voltage. C8, C9 and R11 comprise the compensation network. The output voltage of TL431 is
converted to the current signal via optocoupler IC2 and two resistors R14 and R15 for regulation control.
6
Circuit Operation
6.1
Startup Operation
Since there is a built-in startup cell in the ICE2QR1765G, there is no need for external start up resistor,
which can improve standby performance significantly.
When VCC reaches the turn on voltage threshold 18V, the IC begins with a soft start. The soft-start
implemented in ICE2QR1765G is a digital time-based function. The preset soft-start time is 12ms with 4
steps. If not limited by other functions, the peak voltage on CS pin will increase step by step from 0.32V to
1V finally. After IC turns on, the Vcc voltage is supplied by auxiliary windings of the transformer.
6.2
Normal Mode Operation
The secondary output voltage is built up after startup. The secondary regulation control is adopted with
TL431 and optocoupler. The compensation network C8, C9 and R11 constitute the external circuitry of the
error amplifier of TL431. This circuitry allows the feedback to be precisely controlled with respect to
dynamically varying load conditions, therefore providing stable control.
6.3
Primary side peak current control
The MOSFET drain source current is sensed via external resistor R1A, R1B, R1C and R1D. Since
ICE2QR1765G is a current mode controller, it would have a cycle-by-cycle primary current and feedback
voltage control which can make sure the maximum power of the converter is controlled in every switching
cycle.
6.4
Digital Frequency Reduction
During normal operation, the switching frequency for ICE2QR1765G is digitally reduced with decreasing load.
At light load, the MOSFET will be turned on not at the first minimum drain-source voltage time, but on the nth.
The counter is in range of 1 to 7, which depends on feedback voltage in a time-base. The feedback voltage
decreases when the output power requirement decreases, and vice versa. Therefore, the counter is set by
monitoring voltage VFB. The counter will be increased with low VFB and decreased with high VFB. The
thresholds are preset inside the IC.
6.5
Burst Mode Operation
At light load condition, the SMPS enters into Active Burst Mode. At this stage, the controller is always active
but the Vcc must be kept above the switch off threshold. During active burst mode, the efficiency increase
significantly and at the same time it supports low ripple on Vout and fast response on load jump.
For determination of entering Active Burst Mode operation, three conditions apply:
1. the feedback voltage is lower than the threshold of VFBEB (1.3V). Accordingly, the peak current sense
voltage across the shunt resistor is 0.18;
2. the up/down counter is 7;
3. and a certain blanking time (tBEB =24ms).
Application Note
7
21 May 2012
EVAL-2QR1765G-18W
Once all of these conditions are fulfilled, the Active Burst Mode flip-flop is set and the controller enters Active
Burst Mode operation. This multi-condition determination for entering Active Burst Mode operation prevents
mistriggering of entering Active Burst Mode operation, so that the controller enters Active Burst Mode
operation only when the output power is really low during the preset blanking time.
During active burst mode, the maximum current sense voltage is reduced from 1V to 0.34V so as to reduce
the conduction loss and the audible noise. At the burst mode, the FB voltage is changing like a sawtooth
between 3.0 and 3.6V.
The feedback voltage immediately increases if there is a high load jump. This is observed by one comparator.
As the current limit is 34% during Active Burst Mode a certain load is needed so that feedback voltage can
exceed VLB (4.5V). After leaving active busrt mode, maximum current can now be provided to stabilize V O.
In addition, the up/down counter will be set to 1 immediately after leaving Active Burst Mode. This is helpful
to decrease the output voltage undershoot
7
Protection Features
7.1
Vcc under voltage and over voltage protection
During normal operation, the VCC voltage is continuously monitored. When the Vcc voltage falls below the
under voltage lock out level (VCCoff) or the Vcc voltage increases up to VCCovp, the IC will enter into
autorestart mode.
7.2
Foldback point protection
For a quasi-resonant flyback converter, the maximum possible output power is increased when a constant current
limit value is used for all the mains input voltage range. This is usually not desired as this will increase additional
cost on transformer and output diode in case of output over power conditions.
The internal fold back protection is implemented to adjust the VCS voltage limit according to the bus voltage. Here,
the input line voltage is sensed using the current flowing out of ZC pin, during the MOSFET on-time. As the result,
the maximum current limit will be lower at high input voltage and the maximum output power can be well limited
versus the input voltage.
7.3
Open loop/over load protection
In case of open control loop, feedback voltage is pulled up with internally block. After a fixed blanking time
30ms, the IC enters into auto restart mode. In case of secondary short-circuit or overload, regulation voltage
VFB will also be pulled up, same protection is applied and IC will auto restart.
7.4
Adjustable output overvoltage protection
During off-time of the power switch, the voltage at the zero-crossing pin ZC is monitored for output
overvoltage detection. If the voltage is higher than the preset threshold 3.7V for a preset period 100μs, the
IC is latched off.
7.5
Short winding protection
The source current of the MOSFET is sensed via four shunt resistors R1A, R1B, R1C and R1D in parallel. If
the voltage at the current sensing pin is higher than the preset threshold VCSSW of 1.68V during the on-time of
the power switch, the IC is latched off. This constitutes a short winding protection. To avoid an accidental
latch off, a spike blanking time of 190ns is integrated in the output of internal comparator.
7.6
Auto restart for over temperature protection
The IC has a built-in over temperature protection function. When the controller’s temperature reaches 140 °C,
the IC will shut down switch and enters into autorestart. This can protect power MOSFET from overheated.
Application Note
8
21 May 2012
EVAL-2QR1765G-18W
Circuit diagram
ER2510 5+5
T1
L2
L8*10-2.2uH 0.6
L9*6
NTC1 5R-9
CN2
C7
1
2
104-1206
C6
104-1206
C5
102-1206
C1
222/630V
R2B
100K-1206
V4
INPUT2
EC9 100UF/ 25V
R10B
51R1-1206
R10C
51R1-1206
EC8 100UF/ 25V
51R1-1206
R10A
OUTPUT+
L3
EC7 470UF/ 25V
3
EC2
EC6 470UF/ 25V
R2A
100K-1206
1
PFR40V45-TO220
EC5 470UF/ 25V
MB6S
RA2
4M02-1206
D3
EC4 470UF/ 25V
V+
EC1
33UF/400V
AC
DB1
33UF/400V
MOV1
K275
2
1
CX1
0.1uF/275V
RA1
4M02-1206
F1 T1.6A/250V
CN1
L1
2
L16*8-50mH 0.35
INPUT1
AC
8
OUTPUT-
D1
RS1M
ZD1
22V
0R-1206
R8
R9
0R-1206
R6 0R-1206
R14
1K-1206
R7 0R-1206
7
CS
DW
DW
4
5
6
2
N.C
3
18K2-1206
U31
A
TL431-SOT-23
K
R
FB
2
R11
3
R12
47P-1206
C9
101-1206
C8
104--1206
10K
C2
SFH617A-3
DW
8
DW
10
9
N.C
N.C
11
CY1
222/AC400V
ICE2QR1765G
ZC
U1
1
R4
VCC
GND
12
U2A
R5
43K2
NC
R13
4K87-1206
C3
R1A
R1B
R1C
R1D
4K75-1206
ICE2QR1765G 5V/3.6A DEMO Schematic
R15
332R-1206
R16
D2 US1D
EC3
22UF/35V
R17
NC
R3 10R
C4
104-1206
D6
NC
102-1206
4R99-1206
4R02-1206
4R02-1206
4R99-1206
U2B
SFH617A-3
Figure 2 – Schematics
Application Note
9
21 May 2012
EVAL-2QR1765G-18W
8.1
PCB Top layer
Figure 3 –Component Legend – View from component side
Application Note
10
21 May 2012
EVAL-2QR1765G-18W
8.2
PCB Bottom Layer
Figure 4–Solder side copper – View from solder side
Application Note
11
21 May 2012
EVAL-2QR1765G-18W
9
Component List
Table 1– Component List
Part Type
Items
Designator
1
BD1
Bridge diode, DB107S, 1A/1000V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
C1
C2
C3
C4
C5
C6
C7
C8
C9
CN1
CN2
CX1
CY1
Clamper diode, 2.2nF/630V
47pF/50V, 1206, X7R
1nF/50V, 1206,X7R
104K/50V, 1206,X7R
1nF/50V,1206,X7R
104k/50V, 1206, X7R
104k/50V, 1206, X7R
104k/50V, 1206, X7R
100pF/50V, 1206, X7R
Connector, VH-3A2P
Connector, VH-3A2P
X-cap, 0.1uF/275Vac
Y-cap., 2.2nF/AC400V
1
1
1
1
1
1
1
1
1
1
1
1
1
D1
Fast rectifier 1000V/1A, RS1M,
DO214AC
1
D2
Ultra fast rectifier, 200V/1A, US1D,
DO214AC
Ultra Low VF diode, PFR40V45CT,
45V/40A
E-cap., 33uF/400V, 10*30
E-cap., 33uF/400V, 10*30
E-cap., 22uF/50V
E-cap., 470uF/25V
E-cap., 470uF/25V
E-cap., 470uF/25V
E-cap., 470uF/25V
E-cap., 100uF/25V
E-cap., 100uF/25V
Fuse, 1.6A/250V
Aluminum heat sink
Input CMC, 2X50mH,1A, L16*8
Output D-choke, 2.2uH,4A, L8*10
Jumper, 0.6*10mm
Varistor 0.25W 275V, 07K275
NTC 5Ω, 5D-9,
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
D3
EC1
EC2
EC3
EC4
EC5
EC6
EC7
EC8
EC9
F1
HS1
L1
L2
L3
MOV1
33
NTC
34
R10A
35
R10B
36
R10C
To be contined
Application Note
51.1Ω,1206,1%
51.1Ω,1206,1%
51.1Ω,1206,1%
12
Quantity
Manufacturer
EPCOS
Murata
Murata
Murata
Murata
Murata
Murata
Murata
Murata
EPCOS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
Wurth
EPCOS
1
1
1
1
21 May 2012
EVAL-2QR1765G-18W
Table 1– Component List (continued)
Items
Designator
37
38
39
40
41
R11
R12
R13
R14
R15
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
R1A
R1B
R1C
R1D
R2A
R2B
R3
R4
R5
R6
R7
R8
R9
RA1
RA2
T1
U1
U2
U3
ZD1
Application Note
Part Type
Quantity
18.2KΩ,1206,1%
4.75KΩ, 1206, 1%
4.87KΩ, 1206, 1%
1KΩ, 1206, 1%
332Ω, 1206, 1%
4.99Ω,1206,1%
Manufacturer
1
1
1
1
1
4.99Ω,1206,1%
4.02Ω,1206,1%
4.02OΩ,1206,1%
100KΩ,1206,1%
100KΩ,1206,1%
10Ω, 1206, 1%
10KΩ, 1206, 1%
43.2KΩ,1206,1%
0Ω,1206,1%
0Ω,1206,1%
0Ω,1206,1%
0Ω,1206,1%
4.02MΩ, 1206, 1%
4.02MΩ, 1206, 1%
ER2510 core PC44, Lp=1.3mH
QR CoolSET, ICE2QR1765G
Opto-coupler, SFH617A-3
2.5V reference, AZ431, SOT23
Zener diode, 22V, SOD80
13
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Wurth
Infineon
21 May 2012
EVAL-2QR1765G-18W
10
Transformer Construction
Core and material: ER2510, TDK PC44 (other equivalent ferrite)
(made by
Bobbin: Vertical Version
Primary Inductance: Lp=1.3mH, measured between pin 1 and pin 3 (Gapped to Inductance)
)
Lleakage<1%(13μH type), measured between pin 1 and pin 3 when other pin short
together according the following 3 portions sandwich winding
Figure 5 – Transformer structure
Figure 6 – Transformer complete – top view
Table 2 – wire gauge used of the transformer windings
Start
1
FB
2
4
End
2
FA
3
5
No. of turn
42
4
34
12
Wire size
1 x φ0.28
2 x trippleφ0.55
1 x φ0.28
1 x φ0.28
Layer
1/2 primary
secondary
1/2 primary
Auxiliary
Method
Tight three layers
Tight
Tight three layers
Tight
Note : FA and FB are terminals at PCB which is fly-lead to the board.
Application Note
14
21 May 2012
EVAL-2QR1765G-18W
11
Test Results
11.1
Efficiency and standby performance
Table 3 – Efficiency vs. AC line voltage
Input
(Vac)
85
115
150
180
230
265
Iin (A)
PF
Pin (W)
0.14
0.25
0.36
0.47
0.11
0.21
0.29
0.38
0.10
0.17
0.24
0.31
0.09
0.15
0.21
0.27
0.07
0.13
0.18
0.23
0.07
0.12
0.16
0.21
0.48
0.52
0.55
0.57
0.43
0.46
0.50
0.52
0.39
0.43
0.46
0.47
0.37
0.41
0.43
0.44
0.33
0.38
0.40
0.42
0.32
0.36
0.38
0.40
5.67
11.10
16.81
22.93
5.63
11.06
16.56
22.25
5.62
11.03
16.48
21.94
5.65
11.00
16.44
21.82
5.70
11.05
16.48
21.76
5.74
11.12
16.58
21.84
Vout
(V)
5.046
5.036
5.027
5.017
5.05
5.04
5.03
5.02
5.05
5.04
5.03
5.02
5.05
5.04
5.03
5.02
5.05
5.04
5.03
5.02
5.05
5.04
5.03
5.02
Iout
(A)
0.9
1.8
2.7
3.6
0.9
1.8
2.7
3.6
0.9
1.8
2.7
3.6
0.9
1.8
2.7
3.6
0.9
1.8
2.7
3.6
0.9
1.8
2.7
3.6
Pout
(W)
4.54
9.06
13.57
18.06
4.54
9.06
13.57
18.06
4.54
9.06
13.57
18.06
4.54
9.06
13.57
18.06
4.54
9.06
13.57
18.06
4.54
9.06
13.57
18.06
Eff.
Average eff.
80.10%
81.66%
80.74%
78.77%
80.66%
81.96%
81.95%
81.17%
80.81%
82.18%
82.34%
82.32%
80.38%
82.41%
82.54%
82.77%
79.67%
82.03%
82.34%
83.00%
79.12%
81.52%
81.85%
82.70%
80.32%
81.44%
81.91%
82.03%
81.76%
81.30%
Table 4 – Standby power and efficiency vs. AC line voltage
Pout(W)
Input
(Vac)
85
115
150
180
230
265
No Load
Pin
(mW)
31.67
34.76
41.76
48.66
63.67
79.69
Application Note
1W
Pin
(W)
1.44
1.31
1.34
1.34
1.36
1.39
2W
Pin
(W)
2.59
2.57
2.60
2.61
2.63
2.65
eff.
69.3%
76.4%
74.9%
74.5%
73.3%
72.0%
15
3W
eff.
77.2%
77.7%
76.8%
76.7%
76.1%
75.4%
Pin
(W)
3.83
3.82
3.84
3.87
3.94
4.01
4W
eff.
78.3%
78.6%
78.2%
77.6%
76.1%
74.8%
Pin
(W)
5.04
5.00
5.01
5.03
5.10
5.17
eff.
79.4%
80.0%
79.9%
79.5%
78.4%
77.3%
21 May 2012
EVAL-2QR1765G-18W
Figure 7 – Efficiency vs. output current
Figure 8 – Efficiency vs. AC line voltage
Application Note
16
21 May 2012
EVAL-2QR1765G-18W
Figure 9 – Standby power vs AC line voltage
Figure 10 – Standby efficeincy vs AC line voltage
Application Note
17
21 May 2012
EVAL-2QR1765G-18W
11.2
Line and load regulation
Figure 11 – Line and load regulation
11.3
Vds and Vcs
Vds
V
Vds
V
Vcs
Vcs
Figure 12 – Vds vs Vcs
Figure 13 – Vds vs Vcs
Ch2=Vds, Ch3=Vcs
Ch2=Vds, Ch3=Vcs
Vin=85Vac, Iout=3.6A(full load)
Vin=265Vac, Iout=3.6A(full load)
Vds_max=305V
Vds_max=556V
Application Note
18
21 May 2012
EVAL-2QR1765G-18W
11.4
EMI test results
The conducted EMI was measured in a compliance lab. under test standard EN55022 or CISPR22 Class B.
The demo board was set up at 18W with the input voltage at 115Vac and 230Vac. The Red curve (upper one)
is the Quasi Peak data and the Green cuve (lower one) is the Average data. Both of them can meet the
regulations with >6dB margins.
Figure 14 – 115Vac line results
Figure 15 – 115Vac Neutral results
Application Note
19
21 May 2012
EVAL-2QR1765G-18W
Figure 16 – 230Vac Line results
Figure 17 – 230Vac Neutral results
Application Note
20
21 May 2012
EVAL-2QR1765G-18W
12
Waveforms and Scope Plots
12.1
Startup at Full Load
Vcc
0.38s
Vcc
Vzc
Vzc
Vcs
Vcs
12.9ms
VFB
VFB
VDSc
Figure 18 – Constant Charging VCC at Startup
Figure 19 – Step Softstart
CH1 Supply Voltage, VCC
CH1 Supply Voltage, VCC
CH2 Zero Crossing Voltage, VZC
CH2 Zero Crossing Voltage, VZC
CH3 Current Sense Voltage, VCS
CH3 Current Sense Voltage, VCS
CH4 Feedback Voltage, VFB
CH4 Feedback Voltage, VFB
12.2
Zero Crossing Point During Normal Operation
Vcc
Vcc
VDS
VDS
Vcs
Vcs
VFB
VFB
th
st
Figure 20 – Working at 1 ZC
Figure 21 – Working at 7 ZC
CH1 Supply Voltage, VCC
CH1 Supply Voltage, VCC
CH2 MOSFET Dain-Source Voltage, VDS
CH2 MOSFET Dain-Source Voltage, VDS
CH3 Current Sense Voltage, VCS
CH3 Current Sense Voltage, VCS
CH4 Feedback Voltage, VFB
CH4 Feedback Voltage, VFB
Application Note
21
21 May 2012
EVAL-2QR1765G-18W
12.3
Load Transient Response
Figure 22 – AC Output Ripple Undershoot
Figure 23 – AC Output Ripple Overshoot
10%  100% load, 0.4A/us
100%  10% load, 0.4A/us
CH1 Output Voltage, Vo
CH1 Output Voltage, Vo
CH4 Output Current, Io
CH4 Output Current, Io
12.4
Burst Mode Operation
6th
7th
Figure 24 – Entering Burst Mode
Figure 25 – Leaving Burst Mode
CH1 Supply Voltage, Vcc
CH1 Supply Voltage, Vcc
CH2 Zero Crossing Voltage, VZC
CH2 Zero Crossing Voltage, VZC
CH3 Current Sense Voltage, VCS
CH3 Current Sense Voltage, VCS
CH4 Feedback Voltage, VFB
CH4 Feedback Voltage, VFB
Condition: ZC=7, FB<1.25V, Blanking time = 27ms
Condition: VFB>4.5V
Application Note
22
21 May 2012
EVAL-2QR1765G-18W
12.5
Protection Mode
Figure 26 – Over ZC Latch
Figure 27 – Over Load/Open Loop Protection
CH1 Supply Voltage, Vcc
CH1 Supply Voltage, Vcc
CH2 Zero Crossing Voltage, VZC
CH2 Zero Crossing Voltage, VZC
CH3 Current Sense Voltage, VCS
CH3 Current Sense Voltage, VCS
CH4 Feedback Voltage, VFB
CH4 Feedback Voltage, VFB
Condition: VZC>3.7V
Condition: VFB>4.5V for 30ms
13
References
[1]
ICE2QR1765G datasheet, Infineon Technologies AG, 2011
[2]
ICE2Qxx65/80x Quasi Resonance CoolSET Design Guide (ANPS0053), Infineon Technologies AG,
2010
[3]
Design Tips for flyback converters using the Quasi-Resonant (ANPS0005), Infineon Technologies
AG, 2006
[4]
Converter Design Using the Quasi-Resonant PWM Controller ICE2QS01 (ANPS0003), Infineon
Technologies AG, 2006
[5]
Determine the Switching Frequency of Quasi-Resonant Flyback Converters Designed with
ICE2QS01 (ANPS0004), Infineon Technologies AG, 2006
Application Note
23
21 May 2012
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