Multioutput 30W Evaluation Board for DVD SMPS with ICE2A265 Junyang Luo, Ming Lik Yew and Meng Kiat Jeoh Infineon Technologies Asia Pacific Pte. Ltd. 168 Kallang Way, Singapore 349253 Email: [email protected], [email protected], and [email protected] The board described here was designed as a typical power supply in flyback converter topology with multi output voltage and secondary control. This type of switch mode power supply is particularly suitable as an AC/DC power supply for DVD, VCD and VCR. The PWM controller ICE2A265 chip used for this application is a current-controlled pulse width modulator with integrated CoolMOS™ power switch. ICE2A265 is the second generation CoolSET™ which provides several special enhancements to satisfy the needs for low power standby and protection features. In standby mode frequency reduction is used to lower the power consumption and support a stable output voltage in this mode. In case of failure modes like open loop, overvoltage or overload due to short circuit the device switches in Auto Restart Mode which is controlled by the internal protection unit. By means of the internal precise peak current limitation the dimension of the transformer and the secondary diode can be lower which leads to more cost efficiency. Evaluation board Technical specifications: Input voltage Input frequency Output voltage and current Digital +5V Digital +3.3V Standby +5V Analog +5V Audio +9V Audio -9V Motor +9V VFD display 4.5V Output power Efficiency Switching frequency Standby load condition Standby power 85VAC~265VAC 50Hz, 60Hz 5V 3.3V STB+5V A+5V +9V -9V M+9V -25V Floating 4.5V 23.9W 70% excluding linear regulator 100KHz STB+5V/0.03A only <1W 1.5A 0.7A 0.03A 0.3A 0.2A 0.2A 0.6A 0.03A 0.1A Circuit Description Line Input The AC line input side comprises the input fuse FUSE1 as overcurrent protection. The choke L1, X2capacitors C1 and C2 and Y1-capacitor C8 and C9 as radio interference suppressors. After the bridge rectifier BR1 and the input capacitor C3, a voltage of 80 to 380 VDC depending on input voltage is available. PWM Control and Power Stage The PWM pulse is generated by 8-pin CoolSET™ ICE2A265. ICE2A265 is an integrated power IC which includes both of the current mode PWM controller and power MOSFET with 650V breakdown voltage. The control IC and Power MOS are fabricated by the different optimized chip technologies respectively and no compromise like monolithic approaches is necessary. The control IC is fabricated by the reliable bipolar technology. Moreover, the power stage is handled by evolutionary CoolMOS™ technology. Clamping Network R3, C4 and D1 dissipate the energy of the leakage inductance. Primary Current Sense The primary current is sensed by the external shunt resistor R6. The sense voltage is fed into ICE2A265 and compares to the internal control voltage for PWM control. Output Stage On the secondary side the power is coupled out via a group of fast-acting diodes Df1, D11, D21, D31, D41 and D51. The capacitors Cf1, C11, C21, C31, C41 and C51 provide energy buffering following with the LC filters to reduce the output voltage ripple considerably. Storage Cf1, C11, C21, C31, C41 and C51 are designed to have an internal resistance as small as possible (ESR). This minimizes the output voltage ripple caused by the triangular current characteristic. Q21, Q41 and Q51 are used to cut the current during the standby mode. Two linear regulators are used to provide A+5V and 3.3V with high accuracy. Feedback Loop The output voltage is sensed by the voltage divider of Rc4 and Rc5 and compare to TL431 internal reference voltage. The output voltage of TL431 is transferred to the primary via optocoupler for regulation control. The secondary regulation control is adopted with TL431 and optocoupler. The compensation network Cc1, Cc2, Rc3 constitutes the external circuitry of the error amplifier of TL431. 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 limited by the resistor Rc2. Optocoupler IC2 is used for floating transmission of the control signal to the “FB” input of the ICE2A265. The optocoupler meets DIN VDE 884 requirements. Circuit Operation Startup From the DC input voltage, the chip's starting current supply is derived using the resistors R1 and R2. Because of the low current less than 55uA, high-value resistors can be used. Series connection of the resistors is necessary for reasons of insufficient dielectric strength of the individual resistors. The IC remains inactive during the Vcc charge up. When the voltage on Vcc reaches 13.5V (typ.), the IC turn on threshold voltage, the SMPS is going to start. The Soft-Start function is realized by RC charging circuit of an internal resistor and the external capacitor C7. The pulse width is gradually increased during a soft start. Normal Mode Operation After startup, the secondary output voltage is built up. If the Stby input signal is high, the SMPS will go into in normal mode. The switches Q21, Q41 and Q51 are turned on and the IC is working in 100KHz switching frequency. During normal operation, the power supply is provided via a separate transformer winding with associated rectifier D2. Resistor R4 is used to limit the IC supply current. Standby Mode Operation If the Stby input signal is low, the switches Q21, Q41 and Q51 are off and the output voltages of 5V, 3.3V, A+5V, +9V and –9V are dropped to zero. The DVD microcontroller will switch off most of its function blocks and VFD display is inactive. There is almost no current from M+9V because DC motor does not work. During the standby mode, the voltage on the IC FB pin is low due to the negative feedback regulation. Because of the internal frequency course dependence on FB pin voltage, the switching frequency is reduced to 21.5KHz. It will help to lower the standby power due to the switching loss. Protection Features Overload & open loop protection in normal operation The detection of open loop or overload is provided by two comparators. The detection is activated and IC will go to auto-restart mode when the voltage at pin SST exceeds 5.3V and feedback voltage V FB to exceed the threshold of 4.8V. Open loop protection during start-up The above open loop protection is not active in startup with softstart voltage is lower than 5.3V. The open loop protection is realized by Vcc overvoltage protection during startup when Soft-Start voltage is lower than 4.0V and the voltage at pin FB is above 4.8V. If Vcc exceeds 16.5V (typ.), IC will stop and go to auto-restart mode. This protection will help to prevent the extremely high voltages on secondary output in case of startup at no load condition with open loop fault. Current Limiting There is a cycle by cycle current limiting realized by the Current-Limit Comparator to provide the overcurrent detection. The source current of the integrated CoolMOSä is sensed via an external sense resistor Rsense. By means of Rsense the source current is transformed to a sense voltage Vsense. When the voltage Vsense exceeds the internal threshold voltage Vcsth the Current-Limit-Comparator immediately turns off the gate drive. To prevent the Current Limiting from distortions caused by leading edge spikes a Leading Edge Blanking is integrated at the Current Sense. Current overshoot Minimization by propagation delay compensation In case of overcurrent detection by current sense the shut down of CoolMOS™ is delayed due to the propagation delay of the circuit. This delay causes an overshoot of the peak current Ipeak which depends on the ratio of di/dt of the peak current. A propagation delay compensation is integrated to reduce the tolerance of the dependence on di/dt of the internal current limiting at ±5%. Over temperature protection Thermal Shut Down is latched by the Error-Latch when junction temperature Tj of IC is exceeding an internal threshold of 140°C. In that case the IC switches in Auto Restart Mode. Circuit Diagram PCB layout top layer PCB layout Bottom: Component List: Designators BR1 C1 C10 C11 C2 C21 C22 C3 C31 C32 C4 C41 C42 C43 C5 C51 C52 C53 C6 C7 C8 C9 Cc1 Cc2 Cf1 Cf2 Connector Copt1 Copt2 D1 D11 D2 D21 D31 D41 D51 Df1 FUSE Holder FUSE1 HK1 HK2 HK3 IC1 IC2 IC3 IC4 IC5 JP1 JP2 Type RS204 0.1uF/275V, X2 Not connected 100uF/50V 0.1uF/275V, X2 220uF/16V 100uF/16v 47uF/400 470uF/16V 220uF/16V 10nF/630V 470uF/16V 220uF/16V 220uF/10V 47uF/25V 2200/10 1000uF 470uF/10V 2.2nF 1uF 2200p/250, Y2 2200p/250, Y2 0.1uF 6.8nF 100uF/25V 47uF/25V 4.7nF/250V, Y2 4.7nF/250V, Y2 UF4006 UF4003 1N4148 UF4002 UF5401 UF5401 MBR760 UF4001 1A Heat Sink Heat Sink Heat Sink ICE2A265 SFH617A-3 TL431 L7805 LM1117 Jumper Jumper Qty 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 9 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 JP3 JP4 L1 L2 L21 L31 L41 L51 Lf1 M3 Nut M3 Screw Q21 Q22 Q41 Q42 Q51 R1 R2 R21 R22 R23 R24 R3 R4 R41 R42 R43 R44 R5 R6 Rc1 Rc2 Rc3 Rc4 Rc5 Rf1 RT1 T1 VR1 ZDf1 Jumper Jumper Common mode choke, 50mH Ferrite Bead 20uH 20uH 20uH 20uH 20uH BC639 BC558 BC640 BC548 IPP15N03L 470k, 1/2W 470k, 1/2W 10k 4.7k 10k 1k 82k, 2W 8.2 6.8k 330 4.7k 4.7k 22 0.51ohm, 1/2W 680 1k 10k 2.4k, 1% 2.4k, 1% 10 S235/5 ER28 Transformer S07K275 5V1 1 1 1 1 1 1 1 1 1 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Transformer construction: Layer No. 9 8 7 6 5 4 3 2 1 Start 7 12 14 14 15 16 18 2 5 Stop 9 11 10 13 14 17 17 1 7 No. of Turns 22 3 11 5 5 5 3 8 22 Core Inside Wire Size 1 x Φ0.28mm 1 x Φ0.28mm 1 x Φ0.28mm 3 x Φ0.28mm 3 x Φ0.28mm 3 x Φ0.28mm 8 x Φ0.28mm 1 x Φ0.28mm 1 x Φ0.28mm Core: ER28/N67 Primary Inductance, Lp=269µH, measured between pin 5 and pin 9 (Gapped to Inductance) Primary Secondary Primary 265 220 110 85 32.8 17.3 7.8 31.2 16.9 7.6 29.8 16.4 7.9 29.9 16.5 8.2 Pin(w) Vo1 SMPS Total (+5V) Po(W) Po(w) (Excluding (Including Regulators) Regulators ) 22.87 20.53 4.92 12.46 11.01 4.97 5.77 5.07 5 22.86 20.53 4.92 12.44 11.00 4.97 5.78 5.07 5 22.90 20.55 4.92 12.49 11.03 4.97 5.78 5.07 5.01 22.92 20.57 4.92 12.47 11.02 4.97 5.78 5.07 5.01 3.26 3.27 3.28 3.26 3.27 3.28 3.26 3.27 3.28 3.26 3.27 3.29 Vo2 (+3.3V) 4.92 4.92 4.93 4.92 4.92 4.93 4.92 4.92 4.93 4.92 4.92 4.93 Vo3 (A+5V) 8.85 8.78 8.56 8.83 8.68 8.58 8.86 8.8 8.6 8.88 8.8 8.6 Vo4 (+9V) 9 8.9 9.5 9 8.9 9.5 9 8.9 9.6 9 8.9 9.7 Vo5 (M+9V) -9.22 -9.16 -8.7 -9.22 -9.16 -8.72 -9.25 -9.2 -8.7 -9.28 -9.17 -8.7 Vo6 (-9V) -25.51 -23.41 -21.75 -25.58 -23.49 -21.79 -25.97 -23.65 -21.66 -26.08 -23.46 -21.64 4.42 4.16 3.84 4.43 4.16 3.84 4.46 4.20 3.81 4.49 4.18 3.79 4.96 4.99 5 4.96 4.99 5 4.96 4.99 5.01 4.96 4.99 5.01 Vo7 Vo8 Vo9 (-25V) (F4.5V) (STB+5V) 5V/1.3A, 3.3V/0.7A, A+5V/0.3A, +9V/0.2A, M+9V/0.6A, -9V/0.2A, -25V/0.03A, F+4.5V/0.1A, STB+5V/0.03A 5V/0.6A, 3.3V/0.4A, A+5V/0.2A, +9V/0.1A, M+9V/0.3A, -9V/0.1A, -25V/0.03A, F+4.5V/0.1A, STB+5V/0.03A 5V/0.2A, 3.3V/0.2A, A+5V/0.1A, +9V/0.1A, M+9V/0A, -9V/0.1A, -25V/0.03A, F+4.5V/0.1A, STB+5V/0.03A full load med load light load full load med load light load full load med load light load full load med load light load Load Test Vin(V) full load med load light load Test report: 70% 72% 74% 73% 74% 76% 77% 76% 73% 77% 76% 70% SMPS Efficiency (Excluding Regulators) 63% 64% 65% 66% 65% 67% 69% 67% 64% 69% 67% 62% Total Efficiency (Including Regulators) 265 220 110 85 stby load stby load stby load stby load 0.9 0.8 0.5 0.5 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0 0 0 0 0 0 0 0 0 0 0 0 Standby Test: stby load: STB+5V/0.03A only Vo2 Vo3 Vin(V) Pin(w) SMPS Po(W) Total Po(w) Vo1 (Including (+5V) (+3.3V) (A+5V) (Excluding Regulators) Regulators) 0 0 0 0 Vo4 (+9V) 9.3 9.3 9.1 9.1 Vo5 (M+9V) 0 0 0 0 Vo6 (-9V) -24.42 -24.64 -23.71 -23.87 6.54 6.68 6.30 6.40 5.11 5.11 5.05 5.04 Vo7 Vo8 Vo9 (-25V) (F4.5V) (STB+5V) 18% 20% 32% SMPS Efficiency (Excluding Regulators) 32% 18% 20% 32% Total Efficiency (Including Regulators) 32% Conducted EMI spectrum at 240VAC input References:  Harald Zöllinger and Rainer Kling, ICE2AXXX for OFF-Line Switch Mode Power Supplies (SMPS), Application Note, Infineon Technologies.  CoolSETä-II Off-line SMPS Current Mode Controller with High Voltage 650V/800V CoolMOSä on Board Datasheet, Infineon Technologies.