Version 3.0, Oct. 2003 Application Note AN-EVALSF2-ICE2B765P2-3 CoolSET 80W 24V Evaluation Board using ICE2B765P2 Author: Rainer Kling Published by Infineon Technologies AG http://www.infineon.com/CoolSET Power Management & Supply N e v e r s t o p t h i n k i n g 80W 24V Demoboard with ICE2B765P2 on Board Table of Contents 1 INTRODUCTION ..................................................................................................................................... 2 Application........................................................................................................................................ 2 CoolSET ........................................................................................................................................ 2 LIST OF FEATURES .............................................................................................................................. 3 POWER SUPPLY SPECIFICATION....................................................................................................... 3 SCHEMATIC ........................................................................................................................................... 4 PCB LAYOUT ......................................................................................................................................... 5 DESCRIPTION ........................................................................................................................................ 6 Introduction....................................................................................................................................... 6 Line Input.......................................................................................................................................... 6 Startup .............................................................................................................................................. 6 Operation Mode................................................................................................................................ 6 Softstart ............................................................................................................................................ 6 Snubber Network.............................................................................................................................. 6 Limitation of primary current............................................................................................................. 6 Output Voltage ................................................................................................................................. 7 Regulation ........................................................................................................................................ 7 EMI Behavior .................................................................................................................................... 7 BILL OF MATERIAL ............................................................................................................................... 8 TRANSFORMER CONSTRUCTION DOCUMENTATION ..................................................................... 9 PERFORMANCE DATA ....................................................................................................................... 10 Efficiency ........................................................................................................................................ 10 No-Load Input Power (Standby)..................................................................................................... 11 Regulation and Power Limiting ...................................................................................................... 11 W AVEFORMS AND SCOPE PLOTS .......................................................................................................... 13 Startup @ Low and High AC Line Input Voltage and Nominal Load ............................................. 13 Drain Source Voltage and Current During Normal Operation........................................................ 13 Load Transient Response (Loadjump from 10% Load until 100% Load) ...................................... 14 AC Output Ripple during Nominal Load and Normal Operation .................................................... 14 INPUT CAPACITOR IMPROVEMENT – SLOPE COMPENSATION ................................................................... 15 Input Capacitor Improvement......................................................................................................... 15 Slope Compensation ...................................................................................................................... 15 REFERENCES ...................................................................................................................................... 17 www.Infineon.com/CoolSET Page 1 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Introduction Application This document is an engineering report that describes a universal input power supply designed in a typical off line flyback converter topology that utilizes the ICE2B765P2 CoolSET. The application 1 operates in discontinuous current mode using the frequency reduction during standby condition . The board has one output voltage with secondary regulation. This board demonstrates the basic performance features and the power capability of the F2 CoolSET device ICE2B765P2 of the second generation of CoolSET in a TO220 ISODRAIN package with extended creepage distance for higher electrical strength and isolated tab. CoolSET CoolSET is a current mode control IC and the power MOSFET CoolMOS within one standard package designed for low cost power supplies. CoolSET combines the superior technology of CoolMOS and the optimized technology of the control IC with enhanced protection features and improved standby power concept. The integrated propagation delay compensation (patented by Infineon Technologies) prevents a current overshoot, in combination with the adjustable soft start function, a reduced electrical stress on the MOSFET, the transformer and the output diode will be the 2 3 effect. The 650V / 800V high avalanche rugged CoolMOS eliminates or reduces the need for a heatsink and permits a SMPS design with a simple RCD snubber and a low cost standard transformer design. The lowest area specific Rdson leads to a high efficiency and permits an operation at high ambient temperature. CoolSET permits always a safety operation during any error cases due to the integrated protection features. Figure 1– EVALSF2-ICE2B765P2 This document contains the power supply specification, schematic, bill of material and the transformer construction documentation. Typical operating characteristics are presented at the rear of the report and consist of performance curves and scope waveforms. Note: Design calculations for the components and the transformer are performed in accordance with the application note “AN–SMPS–ICE2AXXX for OFF – Line Switch Mode Power Supplies” and FlyCal, an EXCEL based design software according to the application note AN-SMPS-ICE2AXXX. The application note and FlyCal are available on the Internet: www.Infineon.com/CoolSET 1 POUT = 0W At Tj = 110°C 3 At Tj = 25°C 2 www.Infineon.com/CoolSET Page 2 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board List of Features Feature CoolSET Device ICE2B765P2 External Sense Adjustable Soft Start Modulated Gate Drive Over Load Protection with auto restart Over Current Protection with auto restart Over Temperature Shut Down with auto restart Open Loop Protection with auto restart Under Voltage Lock Out with auto restart 4 Drain Source Voltage 650V Standby Mode: Frequency Reduction (fOSZ = 21 kHz) Internal Leading Edge Blanking 67 kHz operating frequency TO220 ISODRAIN Package with isolated Tab Standby Power according to international Standards Table 1 – List of Features Power Supply Specification Description Input Voltage Line Regulation (85...270V) Input Frequency No Load Input Power (230VAC) Output Voltage AC Output Voltage Ripple Output Current Output Power Peak Power Total Regulation Load Regulation (10...100%) Efficiency (85VAC) @ nominal Load Efficiency (270VAC) @ nominal Load Symbol Min Input Section VACIN 85 f 47 Output Section VOUT 23.75 VRipple IOUT 3.25 POUT 0 POUTmax η η Typ Max Units 115/230 <1 50/60 0.58 270 VAC % Hz W 24 < 0.05 3.3 80 90 ±2 <1 83 89 24.25 64 3.35 85 VDC VP-P ADC W W % % % % Environmental Conducted EMI EN55022B Ambient Temperature TA 0 25 40 °C Thermal Consideration @ VACIN = 85V and Dmax = 50% (∆T @ Ta = 25°C) Transformer 65 °C CoolSET 55 °C Output Diode 65 °C Output Capacitors 40 °C Table 2 – Power Supply Specification 4 VDSBR at Tj = 110°C www.Infineon.com/CoolSET Page 3 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Schematic Figure 2 Power Supply Schematic www.Infineon.com/CoolSET Page 4 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board PCB Layout Figure 3 Board Layout - Component Side www.Infineon.com/CoolSET Page 5 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Description Introduction The EVALSF2-ICE2B765P2 demoboard is a low cost flyback switching power supply using the ICE2B765P2 integrated circuit from the CoolSET-F2 family. The circuit shown in Figure 2 details a 24V, 80W supply that operates from a line input voltage range of 85 up to 265VAC, suitable for applications requiring either an open frame supply or an enclosed adapter. Line Input The AC line input side comprises of an input fuse F1 as line input over current protection as well as choke L5 and the X2 capacitors C8 and C24 as radio interference suppressors. R19 prevents the application against line shut on spikes. After the bridge rectifier BR1 and input capacitor C3, a voltage from 120 to 380 VDC is present. Only a 220µF input capacitor is required due to the wider duty cycle DCMAX of the ICE-F2-family. Startup From the line input voltage, the current supply which is used to charge up the chip supply capacitor C4 is derived by using resistors R7 and rectifier diode D10. Because of the very low start up current of typically 27µA, a high-value resistor can be used to realize the startup. Note: Improve your standby power via increasing R7. Operation Mode During operation, the VCC pin is supplied via a separate transformer winding with associated rectification D2 and buffering C4 and filter capacitor C20. Resistor R8 is used for current limiting during the charging of C4. In order not to exceed the maximum voltage at the VCC pin an external zener diode D7 limits this voltage. During light or no load condition the switching frequency is reduced down to 21kHz in order to reduce the switching losses without audible noise. Note: In order to improve the standby power, set the board in the burst mode during no load condition via increasing the chip supply resistor R8. Softstart In order to minimize the electrical stress, a Soft-Start function is realized by an internal resistor and the adjustable external capacitor C18. Snubber Network Due to the high avalanche rugged CoolMOS inside, a simple RCD snubber protection can be used. The network R10, C12 and D3 clamp the DRAIN voltage spike caused by transformer leakage inductance to a safe value below the drain source break down voltage VDSBR = 650V maximum. Limitation of primary current The CoolMOS drain source current is sensed via external shunt resistors R20 and R21. An accurate value of the shunt improves the peak power limitation shown in the curve peak power limitation in the rear of this report and minimize the electrical stress on the MOSFET, the Transformer and the output rectifier. www.Infineon.com/CoolSET Page 6 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Output Voltage Power is coupled out on the secondary side via a fast-acting diodes D1 and D9 with low forward voltage. Capacitors C5 and C29 performs energy buffering, a following LC - filter C32 and inductor L9 considerably reduces the output voltage ripple. Storage output capacitors C5 and C29 is designed to exhibit a very low ESR in order to minimize the output voltage ripple caused by the triangular current characteristic. The output voltage is set with resistors R1 and R2. The capacitor C33 lower the AC output ripple on the output voltage. Regulation The output voltage is controlled using a type TL431 (IC2) reference diode. This device incorporates the voltage reference as well as the error amplifier and a driver stage. Compensation network C1, C2, R1, R5 constitutes the external circuitry of the error amplifier of IC2. This circuitry allows the feedback to be precisely matched to dynamically varying load conditions, thereby providing stable control. The maximum current through the optocoupler diode and the voltage reference is set by using resistors R3, R4. Optocoupler IC1 is used for floating transmission of the control signal to the “Feedback” input via resistor R9 and capacitor C6 of the ICE2B765P2 control device. The optocoupler used meets DIN VDE 884 requirements for a wider creepage distance. EMI Behavior In order to reduce the conducted EMI behavior, Y – capacitor C7 is set in parallel to the transformer TR1. Note: The value should not exceeds 2.2nF in order to guarantee a safety off line switch mode power supply design. www.Infineon.com/CoolSET Page 7 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Bill of Material Pos. Part Type Number Values Note Ordering Code 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 BR1 C1 [nF] C2 [nF] C3 [µF] C4 [µF] C5 [µF] C6 [nF] C7 [nF] C8 [µF] C12 [nF] C18 [nF] C20 [nF] C24 [µF] C29 [µF] C32 [µF] B380 C5000-3300 470 0.15 220 47 1000 2.2 2.2 0.22 2.2 330 100 0.22 1000 220 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 50V 50V 400V 35V 35V 50V 250V 275V 400V 50V 50V 275V 35V 35V DIOTEC B380C5000-3300 EPCOS B37984M5474K EPCOS B37979G1151J EPCOS B43304B9227M EPCOS B41821A6476M EPCOS B41886S7108M X7R EPCOS B37979G5222J Y1 Cap Röderste WKP2222MCPER X2 Cap EPCOS B81130C1224M MKT EPCOS B32520C6222K X7R EPCOS B37984M5334K X7R EPCOS B37987F5104K X2 Cap EPCOS B81130C1224M Low ESR EPCOS B41886S7108M Low ESR EPCOS B41859A7227M 16 C33 [nF] 470 1 50V EPCOS B37984M5474K 17 D1 MUR1520 1 200V ONS MUR1520 18 19 20 D2 D3 D7 1N4148 1N4937 ZPD18 1 1 1 200V 18V TELEFUNKEN 1N4148 TAP SETRON 1N4937 PHILIPS ZPD18 21 D9 MUR1520 1 200V ONS MUR1520 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 D10 F1 HS1 HS2 HS3 IC1 IC2 IC3 L9 [µH] L5 [µH] 1N4007 Microfuse Heatsink Heatsink TO220 Heatsink TO220 SFH617A-3X006 TL431CLP TO92 ICE2B765P2 1.0 2*27mH R1 [kΩ] 40.0 R2 [kΩ] 4.7 R3 [kΩ] 1.1 R4 [kΩ] 1.6 R5 [kΩ] 180.0 R7 [kΩ] 680 4.3 R8 [Ω] 22.0 R9 [Ω] R10 [kΩ] 33.0 R19 NTC10 R20 [Ω] 0.43 R21 [Ω] 0.39 TR1 SMT19 Haltefed. For Heatsink W1 Wire 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 47 X1, X2 2 Connector 2pol. www.Infineon.com/CoolSET DIOTEC 1N4007 SIBA SICH331 ASSMANN V-7477-X FISCHER FK224 MI P SIP FISCHER FK224 MI P SIP VISHAY SFH617A-3X006 ONS TL431CLP TO92 INFINEON WÜRTHEL 744772010 EPCOS B82734R2172A30 3.15A 6A 1.7A 1% 1% 1% 1% 0.7mm Gap Page 8 from 17 OREGA FISCHER THF104 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Transformer Construction Documentation www.Infineon.com/CoolSET Page 9 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Performance Data Efficiency Efficiency versus AC Line Input Voltage 100 Efficiency [%] 90 80 70 60 50 50 100 150 200 250 300 AC Line Input Voltage [V] Efficiency @ 10W Output Power Figure 4 Efficiency vs. Line Input Voltage Efficiency versus Output power 100 90 80 Efficiency [%] 70 60 50 40 30 20 10 0 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 Output Power[W] Vacin = 85V Vacin = 270V Figure 5 Efficiency vs. Output Power @ Low and High Line 50Hz www.Infineon.com/CoolSET Page 10 from 17 EVALSF2-ICE2B765P2 V3.0 80 80W 24V Demoboard with ICE2B765P2 on Board No-Load Input Power (Standby) Standby versus AC Line Input Voltage 1 0,9 0,8 Input Power [W] 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 50 100 150 200 250 300 AC Line Input Voltage [V] Standby Power Figure 6 Standby Power vs. Line Input Voltage and No Load Condition (Pout = 0W) Regulation and Power Limiting Line Regulation: Vout versus AC Line Input Voltage @ nominal Load 25 24,75 Output Voltage [V] 24,5 24,25 24 23,75 23,5 23,25 23 50 100 150 200 250 300 AC Line Input Voltage [V] Output Voltage Figure 7 Output Voltage Regulation vs. Line Input Voltage www.Infineon.com/CoolSET Page 11 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Load Regulation: Vout versus Load @ Vacin = 230V 25 24,75 Output Voltage [V] 24,5 24,25 24 23,75 23,5 23,25 23 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 Output Power [W] Output Voltage Figure 8 Output Voltage Regulation vs. Load Max. Overload Output Power (Peak Power) versus AC Line Input Voltage 100 98 Max. Overload Output Power [W] 96 94 92 90 88 86 84 82 80 50 100 150 200 250 300 AC Line Input Voltage [V] Peak Power Figure 9 Peak Power (Over Current Shut Off Threshold) vs. Line Input Voltage www.Infineon.com/CoolSET Page 12 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Waveforms and Scope Plots All waveforms and scope plots where recorded with a Tectronix TDS 745D Startup @ Low and High AC Line Input Voltage and Nominal Load Channel 1: Chip Supply Voltage (VCC) Channel 2: Feedback Voltage (VFB) Channel 3: Soft Start Voltage (VSS) Channel 4: Output Voltage (VOUT) Channel 1: Chip Supply Voltage (VCC) Channel 2: Feedback Voltage (VFB) Channel 3: Soft Start Voltage (VSS) Channel 4: Output Voltage (VOUT) Figure 10 Startup @ Vacin = 85V and nom. Load Figure 11 Startup @ Vacin = 270V and nom.Load Drain Source Voltage and Current During Normal Operation Channel 1: Drain Current (ID) Channel 4: Drain Source Voltage (VDS) Dmax = 50% / VRsense = 890mV Channel 1: Drain Current (ID) Channel 4: Drain Source Voltage (VDS) Dmax = 11% / VRsense = 880mV Figure 12 Operation @ Vacin = 85V and nom. Load Figure 13 Operation @ Vacin = 270V and nom.Load www.Infineon.com/CoolSET Page 13 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Load Transient Response (Loadjump from 10% Load until 100% Load) Channel 2: Feedback Voltage (VFB) Channel 2: Feedback Voltage (VFB) Figure 14 Loadjump @ Vacin = 85V and nom. Load Figure 15 Loadjump @ Vacin = 270V and nom.Load AC Output Ripple during Nominal Load and Normal Operation AC Output Voltage Ripple High Frequency Probe Coupling Channel 1: AC Output Ripple (VACOUT) VACOUTmax = ± 10mV Details of AC output voltage ripple measurements. The probe GND should be as short as possible to minimize the high frequency probe coupling. Figure 16 AC Output Voltage Ripple at nom. Load Figure 17 AC Ripple Measurement Technique www.Infineon.com/CoolSET Page 14 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board Input Capacitor Improvement – Slope Compensation Input Capacitor Improvement In case you are using a smaller input capacitor (100µF instead of 220µF), the maximum duty cycle increases. To make sure, that the board is not working in the continuous conduction mode, a different transformer is necessary; otherwise, you have to assemble slope compensation on board. Slope Compensation Any kind of current mode controller needs to have slope compensation in case the application is designed for the continuous conduction mode (CCM) and the maximum duty cycle exceeds the 50% threshold. Below you see the impact on the system in case of an input capacitor reduction; with the 220µF bulk works the board in the discontinuous conduction mode (DCM) and a Dmax < 50% (Figure 18); with the smaller 100µF bulk (1.25µF/W), the board is running in the continuous conduction mode (CCM) and Dmax > 50% (Figure 19). Channel 1: Drain Current (ID) Channel 4: Drain Source Voltage (VDS) CIN = 220µF / Dmax = 50% / Pout = 80W / VACIN = 85V Channel 1: Drain Current (ID) Channel 4: Drain Source Voltage (VDS) CIN = 100µF / Dmax = 71% / Pout = 80W / VACIN = 85V Figure 18 DCM – Operation with Dmax < 50% Figure 19 CCM – Operation with Dmax > 50% To prevents an instability of the regulation loop, in case of CCM and Dmax > 50%, assemble just three more components (2 ceramic capacitors C17 / C18 and one resistor R19) as shown in the circuit diagram below. Figure 20 Circuit Diagram Switch Mode Power Supply with Slope Compensation www.Infineon.com/CoolSET Page 15 from 17 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board More information regarding how to calculate the components of the Slope Compensation see the application note AN_SMPS_16822CCM_V10. For the calculation of the additional components of a SMPS, see in the application note AN_SMPS_ICE2xXXX – available on the internet: www.infineon.com/CoolSET CoolSET F2. Note: The built-in transformer does not comply with EN60950 safety requirements in respect of electrical isolation. Change service Issue status 1.0 2.1 2.2 2.3 3.0 Changes First issue BOM Update Performance Data BOM Update Update: ! Update Boardlayout ! Update BOM ! Different Transformer construction Additional: ! Slope Compensation www.Infineon.com/CoolSET Page 16 from 17 Date 02.05.2002 02.08.2002 27.08.2002 08.11.2002 Oct. 2003 EVALSF2-ICE2B765P2 V3.0 80W 24V Demoboard with ICE2B765P2 on Board References [1] ICE2AXXX for OFF-Line Switch Mode Power Supplies Application Note, Infineon Technologies [2] CoolSET -II Off-line SMPS Current Mode Controller with High Voltage CoolMOS on Board Datasheet, Infineon Technologies Revision History Application Note AN-EVALSF2-ICE2B765P2-3 Actual Release: 3.0 Date: 2003-10-22 Previous Release: V2.3 Page of actual Rel. -- Page of Subjects changed since last release prev. Rel. -- See change service www.Infineon.com/CoolSET Page 17 from 17 EVALSF2-ICE2B765P2 V3.0