Application Note, V1.2, 12 November 2011 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 © 2007 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. Infineon Technologies components may be used in life-support devices or systems only with 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. Title Revision History: 12 November 2011 Previous Version: V1.1 Page Subjects (major changes since last revision) 12, 13 Revise typo in auxiliary winding turns 36W Evaluation Board with Quasi-Resonant PWM Controller ICE2QS03G License to Infineon Technologies Asia Pacific Pte Ltd Eric Kok [email protected] Wang Zan [email protected] He Yi [email protected] Jeoh Meng Kiat [email protected] We Listen to Your Comments Any information within this document that you feel is wrong, unclear or missing at all? Your feedback will help us to continuously improve the quality of this document. Please send your proposal (including a reference to this document) to: [email protected] V1.2 AN-PS0040 EVALQRS-36W-ICE2QS03G Table of Contents 1 Content................................................................................................................ 5 2 Evaluation Board................................................................................................ 5 3 List of Features .................................................................................................. 5 4 Technical Specifications ................................................................................... 5 5 Circuit Description ............................................................................................. 6 5.1 Mains Input and Rectification .....................................................................................................6 5.2 PWM Control ................................................................................................................................6 5.3 Snubber Network .........................................................................................................................6 5.4 Output Stage ................................................................................................................................6 5.5 Feedback Loop.............................................................................................................................6 6 Circuit Operation................................................................................................ 6 6.1 Startup Operation ........................................................................................................................6 6.2 Normal Mode Operation ..............................................................................................................7 6.3 Digital Frequency Reduction ......................................................................................................7 7 Protection Features ........................................................................................... 7 7.1 Vcc under voltage protection .....................................................................................................7 7.2 Foldback point protection...........................................................................................................7 7.3 Open loop/over load protection..................................................................................................7 7.4 Adjustable output overvoltage protection.................................................................................7 7.5 Short winding protection ............................................................................................................7 8 Circuit diagram................................................................................................... 8 8.1 PCB Topover layer.......................................................................................................................9 8.2 PCB Bottom Layer .....................................................................................................................10 9 Component List................................................................................................ 11 10 Transformer Construction............................................................................... 12 11 Test Results...................................................................................................... 13 11.1 Efficiency ....................................................................................................................................13 12 References........................................................................................................ 15 Application Note 4 12 November 2011 EVALQRS-36W-ICE2QS03G 1 Content The demo-board described here is a 36W power supply using quasi-resonant flyback converter topology. The PWM controller ICE2QS03G is a second generation quasi-resonant controller IC developed by Infineon Technologies. The typical applications are for TV-sets, DVD-players, Set-top boxes, netbook adapters, home audio and printer applications. In normal operation, the digital frequency reduction with decreasing load 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. In addition, numerous protection functions have been implemented in ICE2QS03G 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 the secondary diode can be lower which leads to more cost effective design. 2 Evaluation Board Figure 1-EVALQRS-36W-ICE2QS03G 3 List of Features 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 undervoltage protection: IC stop operation, recover with softstart VCC overvoltage protection: IC stop operation, recover with softstart Openloop/Overload protection: Auto Restart after fixed blanking time Output overvoltage protection: Latch-off with adjustable threshold Short-winding protection: Latch-off 4 Technical Specifications Application Note 5 12 November 2011 EVALQRS-36W-ICE2QS03G Input voltage Input frequency Output voltage and current Output power Efficiency Minimum switching frequency at full load, minimum input voltage 5 85VAC~265VAC 50Hz, 60Hz 12V 3A 36W >88% at full load 38kHz 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,and Choke L1 forms a main filter to minimize the feedback of RFI into the main supply. After the bridge rectifier BR1, together with a smoothing capacitor C3, provide a voltage of 80VDC to 380 VDC depending on mains input voltage. 5.2 PWM Control The PWM pulse is generated by the 8-pin Quasi Resonant PWM curremt-mode Controller ICE2QS03G. It comprises the complete control for quasi-resonant flyback switch mode power supply especially in netbook adapter, home audio and printer applications. 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. ICE2QS03G 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 D1 and D5 dissipate the energy of the leakage inductance and to suppress ringing on the SMPS transformer. The Transient voltage suppression diode D5 absorbs the voltage spike larger than 207V. 5.4 Output Stage On the secondary side, 12V output, the power is coupled out via a dual schottky diode D2. The capacitors C12 and C13 provide energy buffering followed by the L-C filters to reduce the output ripple and prevent interference between SMPS switching frequency and line frequency considerably. Storage capacitors C12, C13 are designed to have an internal resistance as small as possible (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 R16, R17 and R18 and compared to TL431 internal reference voltage. C15, C16 and R19 comprise the compensation network. The output voltage of TL431 is converted to the current signal via Optocoupler and two resistors R20 and R21 are for regulation control. 6 Circuit Operation 6.1 Startup Operation When VCC reaches the turn on voltage threshold 18V, the IC begins with a soft start which is realized internally with a built-in digital block. The maximum soft start time is 12ms. During this period, feedback voltage will be generated internally, which is 1.76V at the first step and increases step by step with preset voltage at a time interval of 4ms. In such a way, the primary peak current and the gate drive pulse width are both gradually increased during the soft start. Application Note 6 12 November 2011 EVALQRS-36W-ICE2QS03G 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 C15, C16 and R19 constitutes the external circuitry of the error amplifier of TL431. This circuitry allows the ouput voltage to be precisely controlled to dynamically varying load conditions, therefore providing stable control. 6.3 Digital Frequency Reduction During normal operation, the switching frequency for ICE2QS03G 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 n th. 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. 7 Protection Features 7.1 Vcc under voltage protection During normal operation, the VCC voltage is continuously monitored. When the Vcc voltage falls below the under voltage lock out level (VCCoff), the IC is off and gate signal is disabled. 7.2 Foldback point protection For a quasi-resonant flyback converter, the maximum possible output power will increas when a constant current limit value is used for all the mains input voltage range. This is usually not desired as it will increase additional cost on transformer and output diode incase 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. Resistor R2 determines the foldback point by setting the current flowing out the ZC pin. 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, the IC enters Auto restart mode. In case of secondary short-circuit or overload, regulation voltage VFB will also be pulled up, same protection will be applied and IC will enters Auto restart mode. 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, the IC is latched off. R4 and R2 constitute the voltage divide network.R2 is determined by the foldback point correction voltage. After R2 is determined, R4 can be determined by the over voltage protection point according to the threshold of Vzc OVP voltage. 7.5 Short winding protection The source current of the MOSFET is sensed via shunt resistors R10. 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 implements a short winding protection. To avoid an accidental latch off, a spike blanking time of 190ns is integrated in the output of internal comparator. Application Note 7 12 November 2011 EVALQRS-36W-ICE2QS03G 8 Circuit diagram T1 4 3 P6KE150A 25V 1000uF D1 UF4005 100uF/400V 4 1M IPP60R600CP R22 Q1 1 2 C14 12 4 CON2 470uF 25V 1000uF 25V 6 Com C6 1 275V Np:Ns:Naux=40:5:8 600uH 3 10k R10 0.5R/0.5W R3 0.1uF 33uF/35V C10 39pF 1 7 Vcc 2R R16 39k, 1% 5 HV IC1 4 Gate 4 R20 1.2k 1 3 CS C16 2 R17 6.8k 3 2 FB 2 8 2.2nF 110 1N4148 1 ZC ICE2QS03G 8 Gnd C5 D3 2 C11 R4 8.2k 47K R2 1nF 4 1 3 2 IC2 36W(12V X 3A) SMPS Demo Board using ICE2QS03G and IPP06N600CP(V 1.0) SFH617A-3 100pF R21 680R R19 22k 1 C8 5 C9 2 7 1 3 C15 100nF 3 IC3 TL431 2 22VZD1 R18 12k, 1% Figure 2 – Schematics Application Note J2 2 + C13 1 R13 C12 47pF/1kV 2 1 12V/3A L2 1.5uH D2 VF30100SG 2 N C1 7 C3 BR1 - 800V 2A ~ 1 2 9 D5 3 CON1 1 1 85V ~ 265 V 2A J1 1M R12 2*27mH0.9A L1 2 ~ F1 L 1 2 305V 0.47uF 8 12 November 2011 EVALQRS-36W-ICE2QS03G 8.1 PCB Topover layer Figure 3 – Component side Component Legend – View from Topside Application Note 9 12 November 2011 EVALQRS-36W-ICE2QS03G 8.2 PCB Bottom Layer Figure 4 Solder side copper – View from Topside Application Note 10 12 November 2011 EVALQRS-36W-ICE2QS03G 9 Component List Items Circuit code 1 BR1 2 Description Part No. Manufacturer Bridge rectifier, 2A 800V 2KBB80R C1 X-cap, 0.47uF 305V B32922C3474K 3 C10 39pF, 50V NPO SMD 0805 39pF, 50V, NPO, SMD 0805 4 C11 1nF, 50V NPO SMD 0805 1nF, 50V NPO SMD 0805 5 C12 1000uF/25V KZE 12.5x20 1000uF/25V KZE 12.5x20 6 C13 1000uF/25V KZE 12.5x20 1000uF/25V KZE 12.5x20 7 C14 470uF/25V KZE 8x20 470uF/25V KZE 8x20 8 C15 100nF 50V X7R 0805 100nF 50V X7R 0805 9 C16 100pF 50V NPO 0805 100pF 50V NPO 0805 10 C3 100uF/400V18x26 100uF/400V18x26 11 C5 Y2 cap. 2.2nF/250V Y2 cap. 2.2nF/250V 12 C6 47pF/1kV SL DEA1X3A470JC1B Murata 13 C8 33uF/35V 5x11 B41851A7336M000 Epcos 14 C9 0.1uF 50V X7R, 1206 0.1uF 50V X7R, 1206 15 D1 Ultra-fast diode UF4005 UF4005 Vishay 16 D2 Schottky diode 30A 100V VF30100SG Vishay 17 D3 Mini MELF diode LL4148 LL4148 18 D5 TVS 150V 600W P6KE150A 19 F1 372-2A 20 IC1 ICE2QS03G Infineon 21 IC2 Fuse 2A 250V TR5/372 Quasi-Resonant controller ICE2QS03G (SO-8) Opto-coupler SFH617A-3 SFH617A-3 Vishay 22 IC3 Error Amp regulator TL431 SOT89 TL431 SOT89 23 L1 Input CMC 2*27mH 0.9A B82732F2901B001 Epcos 24 L2 O/P filter 1.5μH 6.3A 13R152C Epcos 25 Q1 CoolMOS 60A 600V IPP60R600CP IPP60R600CP 26 R10 0.5Ω / 0.5W (SMD 2010) WSL2010R5000FEA 27 R12 1MΩ SMD 1206 1MΩ SMD 1206 28 R13 1MΩ SMD 1206 1MΩ SMD 1206 29 R16 39kΩ, 1% SMD 0805 39kΩ, 1% SMD 0805 30 R17 6.8kΩ 1% SMD 0805 6.8kΩ 1% SMD 0805 31 R18 12kΩ, 1% SMD 0805 12kΩ, 1% SMD 0805 32 R19 22kΩ SMD 0805 22kΩ SMD 0805 33 R2 47KΩ SMD 0805 47KΩ SMD 0805 34 R20 1.2kΩ SMD 0805 1.2kΩ SMD 0805 35 R21 680Ω SMD 0805 680Ω SMD 0805 36 R22 10kΩ SMD 0805 10kΩ SMD 0805 37 R3 0Ω SMD 0805 0Ω SMD 0805 38 R4 8.2kΩ SMD 0805 8.2kΩ SMD 0805 Application Note 11 Epcos Vishay Infineon Vishay 12 November 2011 EVALQRS-36W-ICE2QS03G 39 T1 40 ZD1 Lp=0.6mH (N87 RM10) core : B65814N1012D1 22V zener diode mini MELF BZV55B22/TZM525113/ZLL5225 EPCOS Table 1– Component List 10 Transformer Construction Core and material: RM10, N87 Bobbin: 8 pin Version (vertical bobbin) Primary Inductance, Lp=600μH, measured between pin 1 and pin 12 (Gapped to Inductance) Pin 10 8 turns 1 x AWG#29 (Aux.) Pin 3 Pin 12 : not solder to the pin but 38mm length with tubing 10 turns 2 x AWG#28 (Prim.) Pin 12 Pin 7 5 turns 2 x TRIPLE Ø0.45 (Sec.) Pin 6 b Pin 9 Pin 4 Pin 1 Pin 1 : not solder to the pin but 20mm length with tubing c 10 turns 2 x AWG#28 (Prim.) 10 turns 2 x AWG#28 (Prim.) 5 turns 2 x TRIPLE Ø0.45 (Sec.) a 10 turns 2 x AWG#28 (Prim.) Figure 5 – Transformer structure Botom view Top view Figure 6 – Transformer complete – bottom and top view Application Note 12 12 November 2011 EVALQRS-36W-ICE2QS03G Start 3 Stop 10 No. of turns 8 Wire size 1XAWG#29 Layer Auxiliary c 12 10 2XAWG#28 1/4 Primary 6 7 5 2Xtriple wireΦ 0.65 Secondary b c (not broken) 10 2XAWG#28 1/4 Primary a b (not broken) 10 2XAWG#28 1/4 Primary 4 9 5 2Xtriple wireΦ 0.65 Secondary 1 a (not broken) 10 2XAWG#28 1/4 Primary Table 2 Wire size requirement 11 Test Results 11.1 Efficiency Table 3 – Efficiency vs. Load Vin(AC) 115 230 Application Note Load Pin(W) Vout(V) Iout(A) Pout(W) Efficiency 100% load 40.9896 12.003 3.0015 36.027 87.9% 75% load 30.468 12.005 2.2493 27.00285 88.6% 50% load 20.2398 12.007 1.499 17.99849 88.9% 25% load 10.0968 12.009 0.7506 9.013955 89.3% 100% load 40.1994 12.003 3.0012 36.0234 89.6% 75% load 30.1722 12.005 2.249 26.99925 89.5% 50% load 20.1534 12.007 1.499 17.99849 89.3% 25% load 10.284 12.009 0.7509 9.017558 87.7% 13 12 November 2011 EVALQRS-36W-ICE2QS03G Efficiency Vs Load 90.0% 89.6% 89.5% 89.5% 89.3% 89.3% 88.9% 89.0% Efficiency 88.6% 88.5% 87.9% 88.0% 87.5% 87.7% 230Vac 87.0% 115Vac 86.5% 25% 50% 75% 100% Load Figure 7 – Active Load Efficiency 1) No load input power Vs line voltage 45 40.446 40 35 30.858 30 31.994 32.898 34.044 29.058 25 20 90 115 150 180 230 265 Input Line Voltage(Vac) Figure 8 No Load Input Power Vs Line Voltage 1) input discharge resistor R12 and R13 not included Application Note 14 12 November 2011 EVALQRS-36W-ICE2QS03G 12 References [1] ICE2QS03G datasheet, Infineon Technologies AG, 2009 [2] ICE2QS03G design guide, Infineon Technologies, 2010. [ANPS0045] [3] Design tips for flyback converters using the Quasi-Resonant PWM controller ICE2QS01, Infineon Technologies, 2006. [ANPS0005] [4] Converter design using the quasi-resonant PWM controller ICE2QS01, application notes, Infineon Technologies, 2006. [ANPS0003] [5] Determine the switching frequency of Quasi-Resonant flyback converters designed with ICE2QS01, Infineon Technologies, 2006. [ANPS0004] [6] ICE2QRxx65/80x design guide, Infineon Technologies, 2011. [ANPS0053] [7] CoolMOS IPP60R600CP datasheet Rev 2, Infineon Technologies AG, 2008 Application Note ® 15 12 November 2011