20W 5V SMPS Evaluation Board ICE2QR2280G-1

AN - EVAL IC E2QR22 8 0G - 1
2 0 W 5 V SMPS Eva lua ti on Board wi th Quas i Re s onant C oolSE T™ I C E2 QR2 2 8 0 G - 1
Application Note
About this document
Scope and purpose
This document is an engineering report that describes universal input 20 W 5 V off-line flyback converter
using Infineon Quasi-Resonant CoolSET™ ICE2QR2280G-1 which offers high efficiency, very low standby
power, wider VCC operating range and various mode of protections for a high reliable system. This evaluation
board is designed to evaluate the performance of ICE2QR2280G-1 in ease of use.
Intended audience
This document is intended for users of the ICE2QR2280G-1 who wish to design low cost, high efficiency
Quasi-Resonant off-line SMPS for small power supply such as Blu-ray, DVD player, set-top box, game
console, smart meter, charger and auxiliary power of high power system such as LED TV, etc.
Table of Contents
About this document ................................................................................................................... 1
Table of Contents ........................................................................................................................ 1
1
Abstract ..................................................................................................................... 3
2
Evaluation board ........................................................................................................ 3
3
Specification of evaluation board ................................................................................. 4
4
Features of ICE2QR2280G-1 .......................................................................................... 4
5
5.1
5.2
5.3
5.4
Circuit description....................................................................................................... 4
Mains input rectification and filtering ..................................................................................................... 4
Integrated MOSFET and PWM control ..................................................................................................... 4
Output stage .............................................................................................................................................. 5
Feedback loop ........................................................................................................................................... 5
6
6.1
Circuit operation ......................................................................................................... 5
Startup operation...................................................................................................................................... 5
1
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Abstract
6.2
6.3
6.4
6.5
Normal mode operation ........................................................................................................................... 5
Primary side peak current control........................................................................................................... 5
Digital frequency reduction ..................................................................................................................... 5
Burst mode operation............................................................................................................................... 6
7
7.1
7.2
7.3
7.4
7.5
7.6
Protection features ..................................................................................................... 6
VCC over voltage and under voltage protection ...................................................................................... 6
Foldback point protection ....................................................................................................................... 6
Open loop/over load protection .............................................................................................................. 6
Adjustable output overvoltage protection ............................................................................................. 7
Short winding protection ......................................................................................................................... 7
Auto restart for over temperature protection ........................................................................................ 7
8
Circuit diagram ........................................................................................................... 8
9
9.1
9.2
PCB layout ................................................................................................................. 9
Top side ...................................................................................................................................................... 9
Bottom side................................................................................................................................................ 9
10
Component list ......................................................................................................... 10
11
Transformer construction .......................................................................................... 11
12
12.1
12.2
Test results .............................................................................................................. 11
Efficiency, regulations and output ripple .............................................................................................11
Standby power ........................................................................................................................................13
13
References ............................................................................................................... 13
Revision History........................................................................................................................ 13
Application Note
2
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Abstract
1
Abstract
This application note is a description of 20 W switching mode power supply evaluation board designed in a
quasi resonant flyback converter topology using ICE2QR2280G-1 Quasi-resonant CoolSET™ .The target
application of ICE2QR2280G-1 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 ICE2QR2280G-1 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
This document contains the list of features, the power supply specification, schematic, bill of material and
the transformer construction documentation. Typical operating characteristics such as performance curve
and scope waveforms are showed at the rear of the report.
Figure 1
EVAL ICE2QR2280G-1
Application Note
3
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Specification of evaluation board
3
Table 1
Specification of evaluation board
Specification of EVAL ICE2QR2280G-1
Input voltage
85 VAC~265 VAC
Input frequency
50~60 Hz
Output voltage, current & power
5 V, 4 A, 20 W
Minimum switching frequency at full load and minimum input AC
voltage
65 kHz
No-load power consumption
< 50 mW
Active mode four point average efficiency (25%,50%,75% & 100%load)
>80% at 115 VAC & 230 VAC
4
Features of ICE2QR2280G-1
Table 2
Features of ICE2QR2280G-1
800 V avalanche rugged CoolMOS™ with built-in startup Cell
Quasi resonant operation till very low load
Active burst mode operation for low standby input power (< 0.1 W)
Digital frequency reduction with decreasing load for reduced switching loss
Built-in digital soft-start
Foldback point correction, cycle-by-cycle peak current limitation and maximum on time limitation
Auto restart mode for VCC over-voltage protection, under-voltage protection, over-load protection and
overtemperature protection
Latch-off mode for adjustable output over-voltage protection and transformer short-winding protection
Lower VCC turn off threshold
5
Circuit description
5.1
Mains input rectification and filtering
The AC line input side comprises the input fuse F1 as overcurrent protection. The X2 Capacitors C1 and
Choke L1 form a main filter to minimize the feedback of RFI into the main supply. After the bridge rectifier
BR1, together with a smoothing capacitor C2, provide a voltage of 70 VDC to 380 VDC depending on mains
input voltage.
5.2
Integrated MOSFET and PWM control
ICE2QR2280G-1 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. ICE2QR2280G-1 also performs all
necessary protection functions in flyback converters. Details about the information mentioned above are
illustrated in the product datasheet.
Application Note
4
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Circuit operation
5.3
Output stage
On the secondary side, 5 V output, the power is coupled out via a schottky diode D21. The capacitors C21
and C22 provide energy buffering followed by the L-C filters L21 and C23 to reduce the output ripple and
prevent interference between SMPS switching frequency and line frequency considerably. Storage
capacitors C21 and C22 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.
5.4
Feedback loop
For feedback, the output is sensed by the voltage divider of Rc1 and Rc3 and compared to TL431 internal
reference voltage. Cc1, Cc2 and Rc4 comprise the compensation network. The output voltage of TL431 is
converted to the current signal via optocoupler IC2 and two resistors Rc5 and Rc6 for regulation control.
6
Circuit operation
6.1
Startup operation
Since there is a built-in startup cell in the ICE2QR2280G-1, 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 ICE2QR2280G-1 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 Cc1, Cc2 and Rc4 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 R4 and R4A. Since ICE2QR2280G-1 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 ICE2QR2280G-1 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.
Application Note
5
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Protection features
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(1.25 V). 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).
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 1 V to 0.34 V 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 3.6 V.
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 VFBLB (4.5 V). After leaving active busrt mode, maximum current can now be provided to
stabilize VO. 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 over voltage and under voltage protection
During normal operation, the VCC voltage is continuously monitored. When the VCC voltage falls below the
under voltage lock out level (VCC,off) or the VCC voltage increases up to VCC,OVP, 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 V CS 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
30 ms, 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.
Application Note
6
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Protection features
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 3.7 V for a preset period 100 μs, the
IC is latched off.
7.5
Short winding protection
The source current of the MOSFET is sensed via two shunt resistors R4 and R4A in parallel. If the voltage at
the current sensing pin is higher than the preset threshold V CSSW of 1.68 V 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 190 ns 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
7
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Circuit diagram
8
Circuit diagram
Figure 2
Schematic of EVAL ICE2QR2280G-1
Application Note
8
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
PCB layout
9
PCB layout
9.1
Top side
Figure 3
Top side component legend
9.2
Bottom side
Figure 4
Bottom side copper and component legend
Application Note
9
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Component list
10
Component list
Table 3
Bill of materials
No.
Designator
Description
1
BR1
2KBB80R
2
F1
1.6A/250Vac
3
L21
1.5uH
4
R2
2R, SMD
5
R3
32.4k, SMD
6
R4
1.5R
7
R4A
4.7R, SMD
8
R5
4.64k, SMD
9
Rc1
10k, SMD
10
Rc3
10k, SMD
11
Rc4
2.7k
12
Rc5
1K
13
Rc6
68R
14
C1
0.1uF/275V
B32922X2MKP/2H
Epcos
15
C2
68uF/400V
B43501A9686M
Epcos
16
C4
1nF/250V,Y1
17
C5
33uF/50V
B41821
Epcos
18
C6
0.1uF, SMD
19
C7
100pF
20
C8
1nF
21
C21
2200uF/16V
22
C22
2200uF/16V
23
Cc1
0.1uF
24
Cc2
1nF
25
C23
220uF/25V
26
EMI
2 x 27mH, 0.9A
B82732R2901B30
Epcos
27
TR1
1504uH
28
IC2
SFH617A-3
29
IC3
TL431
30
D1
UF4005
UF4005
Vishay
31
D2
1N4148
32
ZD1
22V zener diode
33
ZD2
Zener diode
34
D21
STPS30L45T
Application Note
Part Number
Manufacturer
P6KE200A
10
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Transformer construction
11
Transformer construction
Core and material: EPCOS(N87)or TDK PC44 EF25/13/7
Bobbin: Vertical version
Primary Inductance, Lp=1504 μH( ±10%), measured between pin 4 and pin 5
Start
1
3
7
Stop
2
5
9
No. of turns
12
48
4
Wire size
1XAWG#32
1XAWG#28
3XAWG#25
Layer
Auxiliary
1
/2 Primary
Secondary
6
4
8
3
4
48
3XAWG#25
1XAWG#28
Secondary
1
/2 Primary
Figure 5
Transformer structure
12
Test results
12.1
Efficiency, regulations and output ripple
Table 4
Vin
(VAC)
85
115
230
265
Efficiency, regulation & output ripple
Pin
(W)
Vout
(VDC)
Iout
(A)
Pout
(W)
Efficiency
(%)
0.0207
4.97
0.00
2.4000
4.97
0.40
1.99
82.83
6.1700
12.4500
4.97
1.00
4.97
80.49
4.97
2.00
9.93
79.76
18.9300
4.96
3.00
14.89
78.67
26.0300
4.96
4.00
19.85
76.27
0.0260
4.97
0.00
2.4900
4.97
0.40
1.99
79.84
6.1300
4.97
1.00
4.97
81.01
12.3000
4.97
2.00
9.93
80.73
18.4900
4.96
3.00
14.89
80.54
25.1000
4.96
4.00
19.85
79.09
0.0264
4.97
0.00
2.5700
4.97
0.40
1.99
77.35
6.2500
4.97
1.00
4.97
79.46
12.3000
4.97
2.00
9.93
80.73
18.3500
4.96
3.00
14.89
81.16
24.4300
4.96
4.00
19.85
81.26
0.0308
4.97
0.00
2.5800
4.97
0.40
1.99
77.05
6.3200
4.97
1.00
4.97
78.58
12.3600
4.97
2.00
9.93
80.34
18.4300
4.96
3.00
14.89
80.80
24.5000
4.96
4.00
19.85
81.03
Application Note
11
Average Efficiency
(%)
78.79
80.34
80.65
80.19
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
Test results
Figure 6
Efficiency vs AC line input voltage
Figure 7
Efficiency vs output power @ 115 VAC and 230 VAC line
Application Note
12
Revision 1.1, 2015-04-02
20 W 5 V SMPS Evaluation Board with
Quasi-Resonant CoolSET™ ICE2QR2280G-1
References
12.2
Standby power
Figure 8
Standby power vs AC line input voltage (measured by Yokogawa WT210 power meter integration mode)
13
References
[1]
ICE2QR2280G-1 data sheet, Infineon Technologies AG
[2]
ICE2QRxx65/80x Quasi- Resonant CoolSET™ Design Guide. [ANPS0053]
Revision History
Major changes since the last revision
Page or Reference
Description of change
--
Name change to EVAL
Application Note
13
Revision 1.1, 2015-04-02
Trademarks of Infineon Technologies AG
AURIX™, C166™, CanPAK™, CIPOS™, CIPURSE™, CoolMOS™, CoolSET™, CORECONTROL™, CROSSAVE™, DAVE™, DI-POL™, EasyPIM™, EconoBRIDGE™,
EconoDUAL™, EconoPIM™, EconoPACK™, EiceDRIVER™, eupec™, FCOS™, HITFET™, HybridPACK™, I²RF™, ISOFACE™, IsoPACK™, MIPAQ™, ModSTACK™,
my-d™, NovalithIC™, OptiMOS™, ORIGA™, POWERCODE™, PRIMARION™, PrimePACK™, PrimeSTACK™, PRO-SIL™, PROFET™, RASIC™, ReverSave™,
SatRIC™, SIEGET™, SINDRION™, SIPMOS™, SmartLEWIS™, SOLID FLASH™, TEMPFET™, thinQ!™, TRENCHSTOP™, TriCore™.
Other Trademarks
Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, KEIL™, PRIMECELL™, REALVIEW™, THUMB™, µVision™ of ARM
Limited, UK. AUTOSAR™ is licensed by AUTOSAR development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT Forum. COLOSSUS™,
FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™ of Epcos AG. FLEXGO™ of Microsoft Corporation. FlexRay™ is
licensed by FlexRay Consortium. HYPERTERMINAL™ of Hilgraeve Incorporated. IEC™ of Commission Electrotechnique Internationale. IrDA™ of Infrared
Data Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. MATLAB™ of MathWorks, Inc. MAXIM™ of Ma xim
Integrated Products, Inc. MICROTEC™, NUCLEUS™ of Mentor Graphics Corporation. MIPI™ of MIPI Alliance, Inc. MIPS™ of MIPS Technologies, I nc., USA.
muRata™ of MURATA MANUFACTURING CO., MICROWAVE OFFICE™ (MWO) of Applied Wave Research Inc., OmniVision™ of OmniVision Technologies, Inc.
Openwave™ Openwave Systems Inc. RED HAT™ Red Hat, Inc. RFMD™ RF Micro Devices, Inc. SIRIUS™ of Sirius Satellite Radio Inc. SOLARIS™ of Sun
Microsystems, Inc. SPANSION™ of Spansion LLC Ltd. Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden Co. TEAKLITE™ of CEVA, Inc.
TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA. UNIX™ of X/Open Company Limited. VERILOG™, PALLADIUM™ of Cade nce Design
Systems, Inc. VLYNQ™ of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of Diodes Zetex Limited.
Last Trademarks Update 2011-11-11
www.infineon.com
Edition 2015-04-02
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2015 Infineon Technologies AG.
All Rights Reserved.
Do you have a question about any
aspect of this document?
Email: [email protected]
Document reference
ANEVAL_201501_PL21_007
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