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 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. 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] 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] 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 <100mW@no 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