AN-PS0063-EVAL-ICE2QR1065Z-24W

Application Note, V1.0, 12 March 2012
A pp l i c at i on N ot e
AN- EVAL-ICE2QR1065Z
24W 12V E valuation Board with Quasi Resonant CoolSET® ICE2QR1065Z
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
The information given in this document shall in no event be regarded as a guarantee of
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).
Warnings
Due to technical requirements, components may contain dangerous substances. For information
on the types in question, please contact the nearest Infineon Technologies Office.
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the express written approval of Infineon Technologies, if a failure of such components can
reasonably be expected to cause the failure of that life-support device or system or to affect
the safety or effectiveness of that device or system. Life support devices or systems are
intended to be implanted in the human body or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user
or other persons may be endangered.
EVAL-ICE2QR1065Z-24W
24W 12V Demoboard using ICE2QR1065Z on board
Revision History:
12 March 2012
Previous Version:
Page
V1.0
none
Subjects (major changes since last revision)
®
24W12V Evaluation Board with Quasi-Resonant CooLSET ICE2QR1065Z
License to Infineon Technologies Asia Pacific Pte Ltd
AN-PS0063
Winson Wong
[email protected]
Eric Kok
[email protected]
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Application Note
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EVAL-ICE2QR1065Z-24W
Table of Contents
1
Content ............................................................................................................... 6
2
Evaluation Board ............................................................................................... 6
3
List of Features .................................................................................................. 6
4
Technical Specifications ................................................................................... 7
5
Circuit Description............................................................................................. 7
5.1
Mains Input and Rectification..................................................................................................7
5.2
Integrated MOSFET and PWM Control ....................................................................................7
5.3
Snubber Network .....................................................................................................................7
5.4
Output Stage ............................................................................................................................7
5.5
Feedback Loop.........................................................................................................................7
6
Circuit Operation ............................................................................................... 8
6.1
Startup Operation.....................................................................................................................8
6.2
Normal Mode Operation...........................................................................................................8
6.3
Primary side peak current control...........................................................................................8
6.4
Digital Frequency Reduction ...................................................................................................8
6.5
Burst Mode Operation..............................................................................................................8
7
Protection Features ........................................................................................... 9
7.1
Vcc under voltage and over voltage protection......................................................................9
7.2
Foldback point protection .......................................................................................................9
7.3
Open loop/over load protection...............................................................................................9
7.4
Adjustable output overvoltage protection ..............................................................................9
7.5
Short winding protection .........................................................................................................9
7.6
Auto restart for over temperature protection..........................................................................9
8
Circuit diagram ................................................................................................ 10
8.1
PCB Topover layer .................................................................................................................11
8.2
PCB Bottom Layer .................................................................................................................12
9
Component List ............................................................................................... 13
10
Transformer Construction .............................................................................. 15
11
Test Results ..................................................................................................... 16
11.1
Efficiency and standby performance ....................................................................................16
11.2
EMI Performance....................................................................................................................17
12
Waveforms and scope plots ........................................................................... 19
12.1
Startup at 85Vac and 24W load..............................................................................................19
12.2
Soft-Start with 24W Load .......................................................................................................20
12.3
Load Transient Response......................................................................................................20
12.4
Burst Mode Operation............................................................................................................21
12.5
Protection modes...................................................................................................................22
13
References ....................................................................................................... 23
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EVAL-ICE2QR1065Z-24W
1
Content
This application note is a description of 24W switching mode power supply evaluation board designed in a
®
quasi resonant flyback converter topology using ICE2QR1065Z Quasi-resonant CoolSET .The target
application of ICE2QR1065Z 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 ICE2QR1065Z 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-ICE2QR1065Z-24W
3
List of Features
Industry first IC in DIP7 package with 24W 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
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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
5
85Vac~265Vac
50Hz, 60Hz
12V 2A
24W
>83% at full load
<[email protected] load
40kHz
Circuit Description
5.1
Mains Input and Rectification
The AC line input side comprises the input fuse F1 as overcurrent protection. The X2 Capacitors C1, C2 and
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 C3, provide a voltage of 70VDC to 380 VDC depending on mains
input voltage. A 5.0 Ω NTC resistor is placed in series with input to limit the initial peak inrush current
whenever the power supply is switched on when C3 is fully discharged.
5.2
Integrated MOSFET and PWM Control
ICE2QR1065Z is comprised of a power MOSFET and the quasi-resonant controller; this integrated solution
greatly simplifies the circuit layout and reduces the cost of PCB manufacturing. 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. ICE2QR1065Z 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 snubber network R1, C4, R2, R16, ZD2 and D1 dissipate the energy of the leakage inductance and
suppress ringing on the SMPS transformer. Due to the resonant capacitor C10 paralled to MOSFET drain
souce pin, the overshoot is relatively smaller than fixed frequency flyback converter. Thus the snubber
resistor can be used with a larger one which will reduce the snubber loss.
5.4
Output Stage
On the secondary side, 12V output, the power is coupled out via a dual schottky diode D3. The capacitors
C11 and C16 provide energy buffering followed by the L-C filters L2, C12 and C17 to reduce the output
ripple and prevent interference between SMPS switching frequency and line frequency considerably.
Storage capacitors C11 and C16 are designed to have an internal resistance (ESR) as small as possible.
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 R10, R11 and R12 and compared to TL431
internal reference voltage. C15, C14 and R8 comprise the compensation network. The output voltage of
TL431 is converted to the current signal via optocoupler IC2 and two resistors R6 and R7 for regulation
control.
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6
Circuit Operation
6.1
Startup Operation
Since there is a built-in startup cell in the ICE2QR1065Z, 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 ICE2QR1065Z is a digital time-based function. The preset soft-start time is 12ms with 4
steps. If not limited by other functions, the peak voltageon 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 C14, C15 and R8 constitutes 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 R5, R5A, R5B and R5C. Since
ICE2QR1065Z 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 ICE2QR1065Z 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:
.the feedback voltage is lower than the threshold of VFBEB(1.25V). Accordingly, the peak current sense
voltage across the shunt resistor is 0.18;
.the up/down counter is 7;
.and a certain blanking time tBEB (24ms).
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 switching frequency is set to a fix frequency of 52kHz.
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
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EVAL-ICE2QR1065Z-24W
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 R5, R5A, R5B and R5C 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.
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8
Circuit diagram
Figure 2 Schematic
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8.1
PCB Topover layer
Figure 3 Component Legend – View from topside
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EVAL-ICE2QR1065Z-24W
8.2
PCB Bottom Layer
Figure 4 Solder side copper – View from bottom side
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EVAL-ICE2QR1065Z-24W
9
Component List
Table 1– Component List
Items
Designator
Part Type
Quantity
1
BD1
DF08M, 1.5A/800V
2
C1
0.22uF/275Vac, X2, B32922C3104K000
3
C10
47pF/1000V
4
C11
1000uF/25V
5
C12
470uF/25V
6
C13
N/A
7
C14
100pF/50V, 0805, COG
8
C15
104k/50V, 0805, X7R
9
C16
1000uF/25V
10
C17
104k/50V, 0805, X7R
11
C2
0.22uF/275Vac, X2, B32922C3104K000
12
C3
47uF/400V, B43501A9476M000
13
C4
2.2nF/400V, B32529C8222K000
14
C5
2.2nF/250V, Y1, DE1E3KX222MA4BL01
15
C6
33uF/35V, B41851A7336M000
16
C7
104k/50V, 0805, X7R
17
C8
47pF/50V, 0805, COG
18
C9
102k/50V, 0805, X7R
19
D1
UF4007, 1.0A/1000V
20
D2
UF4007, 1.0A/1000V
21
D3
20A/100V, V20100SG
22
F1
1.6A, Fuse
23
HS1
heatsink
24
IC1
ICE2QR1065Z
25
IC2
PS2501
26
IC3
AZ431
27
J1
wire jumper
28
J2
wire jumper
29
J3
wire jumper
30
JP1
connector
31
JP2
connector
32
L1
2X27mH, 0.9A
33
L2
1.5uH
34
L3
short
35
NTC
S236, 5Ohm
36
R1
150kOhm/2W
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Manufacturer
Epcos
Epcos
Epcos
Epcos
Epcos
Infineon
Epcos
Epcos
To be contined
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Table 1– Component List continued
Items
Designator
Part Type
Quantity
37
R10
28kOhm, 0805, 1%
38
R11
10kOhm, 0805, 1%
39
R12
10kOhm, 0805, 1%
40
R13
N/A
41
R14
43.2kOhm, 0805, 1%
42
R15
10kOhm, 0805, 1%
43
R16
47Ohm, 1206, 1%
44
R2
47Ohm, 1206, 1%
45
R3
100Ohm, 0805
46
R4
N/A
47
R5
3.0Ohm, 0.25W, 1%
48
R5A
3.0Ohm, 0.25W, 1%
49
R5B
2.49Ohm, 0.25W, 1%
50
R5C
2.49Ohm, 0.25W, 1%
51
R6
680Ohm, 0805, 1%
52
R7
1.2kOhm, 0805, 1%
53
R8
20kOhm, 0805, 1%
54
RJ1
0Ohm, 1206, 1%
55
SG1
N/A
56
SG2
N/A
57
TR1
700uH, EE2520, PC40
58
VAR
S07k275
59
ZD1
Zener diode, 22V
60
ZD2
6KE150A
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Application Note
14
Manufacturer
12 March 2012
EVAL-ICE2QR1065Z-24W
10
Transformer Construction
Core and material: EE 2520, TDK PC40
(made by Wurth
)
Bobbin: Vertical Version
Primary Inductance, Lp=700μH, measured between pin 4 and pin 5 (Gapped to Inductance)
Figure 5 – Transformer structure
Figure 6 Transformer complete – top view
Start
4
6
3
7
a
1
End
3
8
a
9
5
2
No. of turn
28
13
28
13
28
16
Wire size
1 x φ0.32
1 x trippleφ0.45
1 x φ0.32
1 x trippleφ0.45
1 x φ0.32
1 x φ0.32
Layer
1/3 primary
secondary
1/3 primary
secondary
1/3 primary
Auxiliary
Method
Tight one layer
Tight
Tight one layer
Tight
Tight one layer
Tight
Table 2 wire gauge used of the transformer windings
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11
Test Results
11.1
Efficiency and standby performance
Table 3 – Efficiency vs. AC line voltage
Vin(Vac)
85
115
230
265
Iin(A)
0.1635
0.3004
0.4282
0.5636
0.1372
0.2432
0.3451
0.4446
0.0832
0.1485
0.2102
0.2715
0.0078
0.135
0.1903
0.2447
PF
0.506
0.5554
0.5854
0.5998
0.4596
0.4987
0.5253
0.5444
0.3675
0.4065
0.4285
0.44
0.3546
0.3913
0.4124
0.4254
Pin(W)
7.036
14.2
21.336
28.75
6.954
13.955
20.85
27.89
7.321
13.89
20.72
27.47
7.456
13.98
20.81
27.61
Vout(V)
11.995
11.991
11.987
11.984
11.995
11.991
11.987
11.984
11.995
11.991
11.987
11.984
11.995
11.991
11.987
11.984
Iout(A)
0.5
1
1.5
2
0.5
1
1.5
2
0.5
1
1.5
2
0.5
1
1.5
2
Pout(W)
5.9975
11.991
17.9805
23.968
5.9975
11.991
17.9805
23.968
5.9975
11.991
17.9805
23.968
5.9975
11.991
17.9805
23.968
eff(%)
85.24019
84.44366
84.27306
83.36696
86.24533
85.92619
86.23741
85.93761
81.92187
86.32829
86.77847
87.25155
80.43857
85.77253
86.40317
86.80913
Efficiency (%)
Efficiency Vs Output Current
Ta = 25 Deg C.
88
87
86
85
84
83
82
81
80
0.5
1
1.5
Output Current (A)
Vin=85Vac
Vin=230Vac
2
Vin=115Vac
Vin=265Vac
Figure 7 – Efficiency vs. AC line voltage
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EVAL-ICE2QR1065Z-24W
Input Power (W)
Standby Power Vs Input Voltage
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0.0695
0.0348
0.0384
85
115
0.0447
0.0744
0.0496
no load
150
180
Input Voltage (Vac)
230
265
Figure 8 Standby input power vs AC line voltage
11.2
EMI Performance
Figure 9 EMI performance of 115Vac Line
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Figure 10 EMI performance of 115Vac Neutral
Figure 11 EMI performance of 230Vac Line
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Figure 12 EMI performance of 230Vac Neutral
Remarks:
To further improve the EMI performance on 230Vac low frequency, it can increase the capacitance on the XCAP.
12
Waveforms and scope plots
12.1
Startup at 85Vac and 24W load
Figure 13 Startup @ 85Vac
Figure 14 Startup @ 265Vac
Ch1 VCC Supply Voltage
Ch1 VCC Supply Voltage
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
Test Condition: 85Vac input, 2A Load
Test Condition: 265Vac input, 2A Load
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12.2
Soft-Start with 24W Load
Figure 15 Soft-Start @ 85Vac
Figure 16 Soft-Start @ 265Vac
Ch1 VCC Supply Voltage
Ch1 VCC Supply Voltage
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
Test Condition: 85Vac input, 2A Load
Test Condition: 265Vac input, 2A Load
12.3
Load Transient Response
Figure 17 AC output ripple overshoot
Figure 18 AC output ripple undershoot
Ch1 Output Current, Iout
Ch1 Output Current, Iout
Ch4 Output Voltage, Vout
Ch4 Output Voltage, Vout
Test Condition: Load 100% to 10% 100Hz, 0.4A/us
Test Condition: Load 10% to 100% 100Hz, 0.4A/us
Measured with decouple capacitor 0.1uF, and 10uF
Measured with decouple capacitor 0.1uF, and 10uF
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12.4
Burst Mode Operation
Figure 19 Entering Burst Mode Operation
Figure 20 Leaving Burst Mode Operation
Ch1 Feedback Voltage, VFB
Ch1 Feedback Voltage, VFB
Ch2 Zero Crossing Voltage, VZC
Ch2 Zero Crossing Voltage, VZC
Ch3 Current Sense Voltage, VCS
Ch3 Current Sense Voltage, VCS
Ch4 Output Voltage, Vo
Ch4 Output Voltage, Vo
th
Test Condition: 265Vac, Load changed fr. 6 ZC to 0A Test Condition: 265Vac, Load changed fr. 0A to 2A
Figure 21 Active Burst Mode Operation
Figure 22 Active Burst Mode Operation
Ch1 Feedback Voltage, VFB
Ch1 Feedback Voltage, VFB
Ch2 Zero Crossing Voltage, VZC
Ch2 Zero Crossing Voltage, VZC
Ch3 Current Sense Voltage, VCS
Ch3 Current Sense Voltage, VCS
Ch4 Output Voltage, Vo
Ch4 Output Voltage, Vo
Test Condition: 85Vac, under BMO
Test Condition: 265Vac, under BMO
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12.5
Protection modes
Figure 23 VCC Over-voltage Protection
Figure 24 Over Load/ Open Loop Protection
Ch1 Feedback Voltage, VFB
Ch1 Feedback Voltage, VFB
Ch2 Zero Crossing Voltage. VZC
Ch2 Zero Crossing Voltage. VZC
Ch3 Current Sense Voltage, VCS
Ch3 Current Sense Voltage, VCS
Ch4 VCC Supply Voltage
Ch4 VCC Supply Voltage
Test Condition: open the zener clamping with
Test Condition: Load Stepping fr. 2A to 3A
overload at high-line
Figure 25 Output Over-voltage Protection
Figure 26 Drain Source Voltage @ low line
Ch1 Feedback Voltage, VFB
Ch2 Drain-source voltage, VDS
Ch2 Zero Crossing Voltage. VZC
Ch3 Current Sense Voltage, VCS
Ch3 Current Sense Voltage, VCS
Test Condition: 85Vac, Full Load (2A)
Ch4 VCC Supply Voltage
Test Condition: change the ZC resistor divider ratio
Application Note
22
12 March 2012
EVAL-ICE2QR1065Z-24W
Figure 27 Drain Source Voltage @ low line
Ch2 Drain-source voltage, VDS
Ch3 Current Sense Voltage, VCS
Test Condition: 265Vac, Full Load (2A)
13
References
[1]
ICE2QR1065Z 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
12 March 2012
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