EVL6591-90WADP

AN2852 Application note EVL6591-90WADP: 90 W AC-DC asymmetrical half-bridge adapter using L6591 and L6563 Introduction This document describes the characteristics and performance of a 90 W wide range input AC-DC adapter based on asymmetrical half-bridge topology (AHB). The converter comprises a two-stage approach: a PFC front-end stage using the L6563 TM PFC controller and a DC-DC stage that implements the asymmetrical half-bridge (AHB) topology driven by the L6591, the new PWM controller dedicated to this architecture. Thanks to the AHB topology, the system offers good electrical performance (EPA 2.0 compliant) with a low-voltage and high-current output (12 V - 7.5 A). The order code for this demonstration board is EVL6591-90WADP. Figure 1. EVL6591-90WADP demonstration board AM01816v1 January 2009 Rev 1 1/35 www.st.com Contents AN2852 Contents 1 Main characteristics and circuit description . . . . . . . . . . . . . . . . . . . . . 4 2 Operating waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 2.1 Asymmetrical half-bridge (AHB) typical waveforms . . . . . . . . . . . . . . . . . . 7 2.2 Low-load operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.3 Short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.4 Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.5 Startup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Electrical performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.1 Efficiency measurement and no-load consumption . . . . . . . . . . . . . . . . . 17 3.2 Harmonic content measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4 Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5 Conducted noise measurements (pre-compliance test) . . . . . . . . . . . 24 6 Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 7 PFC coil specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 8 7.1 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 7.2 Mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AHB transformer specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 8.1 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 8.2 Mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 9 PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2/35 AN2852 List of figures List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Figure 27. Figure 28. Figure 29. Figure 30. Figure 31. Figure 32. Figure 33. Figure 34. Figure 35. EVL6591-90WADP demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 EVL6591-90WADP schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 AHB primary side key waveforms at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Detailed AHB zero-voltage switching at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Detailed AHB zero-voltage switching at half load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 AHB secondary side key waveforms at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Burst mode at no load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Detailed burst mode at no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Load transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Detailed short-circuit behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 HICCUP mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Detailed OVP intervention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 OVP intervention: system is latched . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Complete startup sequence at 115Vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Detailed startup sequence at 115Vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Efficiency vs. O/P power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 No-load consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 EN61000-3-2 measurements at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 JEIDA-MITI measurements at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 EN61000-3-2 measurements at 75 W input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 JEIDA-MITI measurements at 75 W input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 PF vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 THD vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Thermal map at 115Vac - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Thermal map at 230Vac - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 CE peak measure at 115Vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 CE peak measure at 230Vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Bottom view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Windings position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Top view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Topside silk screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Bottomside silk screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Copper traces (bottomside) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3/35 Main characteristics and circuit description 1 AN2852 Main characteristics and circuit description The main characteristics of the SMPS adapter are as follows: ● Input mains range – Vin: 88 ~ 264 Vrms – f: 45 ~ 66 Hz ● Output: 12Vdc ± 2% - 7.5 A ● No-load: Pin below 0.35 W ● Protections ● – Short-circuit – Overload – Ouput overvoltage – Brownout PCB type and size – CEM-1 – Single-side 70 µm – 174 x 78 mm ● Safety: according to EN60065 ● EMI: according to EN50022 - class B The adapter implements a two-stage solution. The front-end PFC uses a boost topology working in transition mode (TM). The IC used is the L6563, advanced TM PFC controller, which integrates all the functions and protection needed to control the stage and an interface with the downstream DC-DC converter. The power stage of the PFC comprises inductor L2, MOSFET Q1, diode D4 and capacitor C9. The PFC circuit is quite standard and already well described in previous ST application notes. Therefore this note will focus on the AHB stage and its controller, the L6591. This DCDC converter comprises a half-bridge (MOSFET Q3 and Q4) connected to the output voltage of the PFC stage that drives the series connection of a DC blocking capacitor (C44) and the primary of the transformer (T1). The transformer has two secondary windings with a center tap connection tied to ground. The other ends are connected to the output diodes D12 and D13. The output inductor is between the common cathode of diodes D12 and D13 and the output. The L6591 includes a current mode PWM controller (fixed-frequency solution), gate drivers for both low and high-side MOSFETs with integrated bootstrap diode and all the functions and protections tailored for this topology. The device is housed in an SO-16 narrow package. This adapter uses the magnetizing current and the output inductor current ripple to obtain the correct primary current direction to achieve zero-voltage switching (ZVS) at turn-on of both MOSFETs. The transformer construction is quite simple as it is a layer type with the primary winding split in two parts (sandwich configuration) and two secondary windings. The primary leakage inductance is about 3% of the magnetizing inductance. The half-bridge is operated at fixed frequency with complementary duty cycles on the two MOSFETs. The high-side FET is on during the D time and the low-side FET is on for the 1-D time. C44 is calculated in order to have a resonance frequency due to Lm and C44 well below the switching frequency (that, in this application, has been set at about 100 kHz). In this way the voltage on C44 is nearly constant and equal to Vin x D where Vin is the high-voltage input 4/35 AN2852 Main characteristics and circuit description bus and D is the duty cycle. For stability reasons related to the topology, the IC limits the maximum duty cycle at 50%. The current in the primary tank circuit is read by the controller thanks to the sense resistors R81 and R82. The self supply is basically obtained thanks to an auxiliary winding on the AHB transformer. A small charge pump on the auxiliary windings of the PFC inductor helps during the startup phase. A pin dedicated to startup sequencing, a spare latched protection (dedicated here to output overvoltage protection), the soft-start function, the overload protection, an interface with the PFC controller and the integrated high-voltage startup generator complete the features of the L6591. All the functions and protections are detailed in the following sections. 5/35 C12 470NF R14 18K R55 0R0 R2 1M2 R1 1M0 R18 56K C22 220PF R26 240K R15 150K C11 10NF C13 1uF C14 100NF 7 6 5 4 3 2 1 C10 1N0 L6563 R27 470 PFC_OK TBO VFF CS MULT COMP INV U1 8 5 1 8 9 10 11 12 13 R89 100K + R20 0R0 R21 27R C15 22uF R100 0R0 C16 1N0 C39 100NF R54 0R0 0R0 R101 R22 0R47 R46 100K Q1 R19 56K STP12NM50FP R23 0R47 + R99 15K C48 6.8NF D27 LL4148 C49 330PF U5B PC817 3 4 C47 2.2NF C5 470NF 400V 4 10NF U3B PC817 C52 100NF 8 7 6 5 3 2 1 R71 10R C17 N.M. D21 1N4148 220PF C41 4N7 D22 LL4148 C40 10NF R70 33R R78 19K6 C43 C45 220K R98 L2 700uH 3 10 5 8 4 14 R80 1K0 PWM_LATCH PWM_STOP RUN ZCD GND GD VCC C3 2N2 - + 88 - 264Vac L1 86A-5163 D29 LL4148 C1 470nF 4 3 D3 1N4005 PFC_STOP COMP VREF OSC SS ISEN DIS LINE U2 L6591 R84 220R Vcc LVG GND N.C. FGND HVG BOOT 9 10 11 12 13 14 15 R9 82K 2 N.M. + C51 22uF R77 56R D24 LL4148 R75 56R D23 LL4148 R72 10R R74 10R + R53 0R0 R3 680K Q3 STP12NM50FP C57 100uF D26 STPS1L60A R81 0R82 R79 100K R17 0R0 R82 0R82 C44 220NF Q4 250V STP12NM50FP R73 100K R28 24K9 R13 8.2K R12 3M0 R8 680K R10 15K R11 3M0 R7 680K R69 3 R90 0R0 C50 100NF C42 100NF + D20 N.M. Q9 NM C9 47uF 450V 16 2R5 R6 HVSTART D4 STTH2L06 U3A PC817 6 5 4 14 12 10 9 R95 47R R83 6K8 T1 AHB Traf o 2 R94 12R 2N2 C21 2N2 C20 1 2 C53 N.M. U4 TS3431 1 75K R91 R88 2K2 R85 220K R93 3K3 1uF C54 C59 470PF D13 STPS30100ST JP9 N.M. D12 STPS16L40CT C58 1N8 L3 3.3uH R86 33K C55 N.M. R87 N.M. D25 C61 N.M. R97 N.M. + C46 1000uF 25V C62 N.M. + R96 470 D28 R25 4.7K U5A PC817 + D1 GBU6J 1 BZV55-B13 1 2 3 C4 470NF 1 2 C2 2N2 C56 100NF 1 R24 1.8K BZV55-B11 F1 T4A 2 3 J2 1 R29 100K 12V-7.5A Output connector 2 1 Q10 BC847C 3 2 6/35 R30 2K2 Q11 BC847C 3 Figure 2. 2 J1 Input connector Main characteristics and circuit description AN2852 EVL6591-90WADP schematic AM01817v1 AN2852 Operating waveforms 2 Operating waveforms 2.1 Asymmetrical half-bridge (AHB) typical waveforms As mentioned before, this application note focuses on the AHB stage. This DC-DC converter has the 400 V PFC bus as input and delivers 12 V at the output. In Figure 3 the primary side key waveforms with full load applied are shown. Figure 4 shows the detail of the two transitions during one switching cycle. When the LVG signal goes down, the current is negative and so the half-bridge node (that has a certain capacitance value due to the Coss of the MOSFETs and the stray capacitance of the circuit) is charged up to 400 V. After the deadtime has elapsed the high-side driver is turned on with zero volts across the high-side MOSFET drain-source pins. The driver activation is visible on the HVG signal when there is the small voltage step on the high part of the waveform. When the high-side driver is turned off, the primary current is positive, so the half-bridge node is discharged down to zero volts and the body diode of Q4 is activated. After the deadtime the LVG turns on in ZVS condition. Figure 3. AHB primary side key waveforms at full load Ch1: LVG pin voltage (yellow) Ch3: HVG pin voltage (purple) Ch4: primary winding current (green) AM01818v1 Typically, in the AHB topology, the most critical transition is the one between LVG turn-off and HVG turn-on. In fact it is visible that the current available to move the half-bridge point is less with respect to the other transition. This is due to the magnetizing current that is not symmetrical with an average value of zero amps but has a certain offset due to the asymmetrical driving of the tank circuit. The fast current variation during transitions is due to the reversal of the current direction in the secondary windings. The effort in this design was to maintain a negative current after 7/35 Operating waveforms AN2852 the positive variation at LVG turn-off. This was done by a correct design of the magnetizing current, output inductor current ripple and choice of turns ratio. Figure 4. Detailed AHB zero-voltage switching at full load Ch1: LVG pin voltage (yellow) Ch3: HVG pin voltage (purple) Ch4: primary winding current (green) AM01819v1 The ZVS condition is harder to meet as the load increases, so full load is the worst condition to have for a correct ZVS operation. In Figure 5 the same waveforms are shown with half load. Since the output current is reduced, the fast primary side current variations are also reduced and so the magnetizing current (that remains basically the same if the load changes) becomes proportionally higher. The result is that there is more current available for moving the half-bridge node. 8/35 AN2852 Operating waveforms Figure 5. Detailed AHB zero-voltage switching at half load Ch1: LVG pin voltage (yellow) Ch3: HVG pin voltage (purple) Ch4: primary winding current (green) AM01820v1 The key waveforms at the secondary side are shown in Figure 6. It is interesting to note that, while the current is swapped between the two diodes, the voltage at their cathode is nearly zero. Figure 6. AHB secondary side key waveforms at full load Ch1: D12 and D13 common cathode voltage (yellow) Ch2: diode D12 current (blue) Ch3: FGND pin voltage (purple) Ch4: diode D13 current (green) AM01821v1 9/35 Operating waveforms AN2852 Another peculiarity of this topology is that, since it is asymmetrical, the diode D13 has to carry higher average and RMS current and sustain higher reverse voltage with respect to diode D12. This implies that D13 dissipates a lot more than D12 and makes sense, in order to improve efficiency and save money, to have a synchronous rectification only on D13. 2.2 Low-load operation At light loads (and no-load) conditions the system enters a controlled burst mode operation, allowing input power reduction. The burst mode is activated according to the COMP pin level. In Figure 7 and Figure 8 the burst mode operation with no load is shown. Under a certain load also the PFC stage works in burst mode operation (specifically the PFC enters in burst mode for a load value higher than the one for the AHB). Using the PFC_STOP pin of the L6591 and the PFC_OK pin of the L6563, a simple interface is built in order to keep the burst modes of the two ICs synchronized. This operation allows fast response to a heavy load transition since the PFC is already on when the power is needed. This avoids output voltage dips. The load transition from 0 to 100% and vice versa can be seen in Figure 9. Figure 7. Burst mode at no load Ch1: LVG pin voltage (yellow) Ch2: Q1 (PFC MOSFET) gate (blue) Ch3:PFC output voltage Ch4: COMP pin voltage (green) 10/35 AM01822v1 AN2852 Operating waveforms Figure 8. Detailed burst mode at no load Ch1: LVG pin voltage (yellow) Ch2: Q1 (PFC MOSFET) gate (blue) Ch3:PFC output voltage Ch4: L6563 PFC_OK pin voltage (green) Figure 9. AM01823v1 Load transitions Ch2: output voltage (blue) Ch4: output current (green) AM01824v1 11/35 Operating waveforms 2.3 AN2852 Short-circuit protection A short-circuit at the output activates the overload protection (OLP). Figure 10 shows the pins involved in this function. When the short-circuit is applied, the COMP pin saturates high. The IC detects this condition and starts charging the SS capacitor. When the SS voltage reaches 5 V, the system shuts down. Diode D29 allows the SS voltage to be clamped at about 5.4 V and the protection has an auto-restart behavior. If the short circuit is not removed, the IC enters the HICCUP mode (Figure 11). When the IC is stopped by the OLP, the high-voltage startup generator is invoked only when Vcc falls to 5 V (VCCrestart). Thanks to this approach, the period between two restart trials is quite long which reduces the stress on power components. Figure 10. Detailed short-circuit behavior Ch1: SS pin voltage (yellow) Ch2: COMP pin voltage (blue) Ch3: FGND pin voltage (purple) Ch4: PFC_STOP pin voltage (green) 12/35 AM01825v1 AN2852 Operating waveforms Figure 11. HICCUP mode Ch1: SS pin voltage (yellow) Ch2: COMP pin voltage (blue) Ch3: FGND pin voltage (purple) Ch4: PFC_STOP pin voltage (green) 2.4 AM01826v1 Overvoltage protection Since it is impossible to sense the output voltage from the primary side in all load conditions, the OVP senses such voltage directly on the output. A Zener diode (D25) is used as the threshold to activate the protection. The information is passed to the controller using optocoupler U5 that increases the disable pin voltage over the intervention threshold of 4.5 V. In Figure 12 a loop failure is simulated by shorting R93. The overvoltage protection is invoked and the output voltage reaches a maximum voltage of 14.8 V. Since this protection uses the disable pin, it is latched. Hence, after PWM is stopped, the HV generator is invoked to keep Vcc voltage between 14 V and 13.5 V. Diode D27 brings the PFC_OK pin voltage over 2.5 V, so the L6563 is also shut down and its consumption goes almost to the startup level. The PWM_LATCH goes high which also keeps the disable pin high. The latched operation is shown in Figure 13. 13/35 Operating waveforms AN2852 Figure 12. Detailed OVP intervention Ch1: output voltage (yellow) Ch2: Vcc pin voltage (blue) Ch3: FGND pin voltage (purple) Ch4: DISABLE pin voltage (green) AM01827v1 Figure 13. OVP intervention: system is latched Ch2: Vcc pin voltage (blue) Ch4: DISABLE pin voltage (green) 14/35 AM01828v1 AN2852 2.5 Operating waveforms Startup sequence In this converter the startup sequence is quite particular and merits a detailed explanation. When the mains is plugged in, the rectified input voltage is present on bulk capacitor C9. Since this value is greater than 80 V, the HV startup generator of the L6591 is turned on and Vcc capacitors are charged with a constant current of about 0.75 mA. This charge time is therefore independent of input voltage level. The L6563 has a turn-on threshold lower than that of L6591, so the PFC controller starts first. The HV startup current is insufficient to power the L6563, so a small charge pump (R70, C40, D21 and D22) is connected to the PFC inductor auxiliary winding. With this circuit, when the L6563 starts, both Vcc voltage and PFC output voltage increase. Once Vcc > 14 V and line pin voltage is greater than 1.25 V, the L6591 also turns on. At this point the charge pump is insufficient to sustain Vcc current of both ICs and so an auxiliary winding on the AHB transformer is used to provide, together with the charge pump, the power requested by the devices. The complete sequence is shown in Figure 14, while the details of the turn-on of both ICs are shown in Figure 15. Both figures show the startup at 115Vac mains input. The startup at 230Vac is very similar, the only difference is that the Vcc voltage during steady state operation is a little higher since the charge pump delivers more current. Figure 14. Complete startup sequence at 115Vac and full load Ch1: LVG voltage (yellow) Ch2: Vcc pin voltage (blue) Ch3: PFC output voltage (purple) Ch4: output voltage (green) AM01829v1 15/35 Operating waveforms AN2852 Figure 15. Detailed startup sequence at 115Vac and full load Ch1: LVG voltage (yellow) Ch2: Vcc pin voltage (blue) Ch3: PFC output voltage (purple) Ch4: output voltage (green) 16/35 AM01830v1 AN2852 Electrical performance 3 Electrical performance 3.1 Efficiency measurement and no-load consumption Table 1 and 2 give the efficiency measurements taken at the two nominal voltages. Table 1. Efficiency at 115Vrms Load [%] Iout [A] Vout [V] Pout [W] Pin [W] Eff [%] 5% 0.3746 12.12 4.54 6.80 66.77% 10% 0.7507 12.11 9.09 12.10 75.13% 20% 1.5037 12.10 18.19 21.98 82.78% 25% 1.8787 12.09 22.71 26.83 84.66% 40% 3.0037 12.09 36.31 41.49 87.53% 50% 3.7537 12.08 45.34 51.41 88.20% 60% 4.5037 12.08 54.40 61.44 88.55% 75% 5.6287 12.07 67.94 76.67 88.61% 80% 6.0037 12.07 72.46 81.77 88.62% 100% 7.5037 12.06 90.49 102.48 88.30% Table 2. Efficiency at 230Vrms Load [%] Iout [A] Vout [V] Pout [W] Pin [W] Eff [%] 5% 0.3746 12.12 4.54 6.58 68.97% 10% 0.7507 12.11 9.09 12.41 73.26% 20% 1.5037 12.10 18.19 22.30 81.59% 25% 1.8787 12.09 22.71 27.02 84.06% 40% 3.0037 12.08 36.28 41.37 87.71% 50% 3.7537 12.08 45.34 51.05 88.82% 60% 4.5037 12.07 54.36 60.83 89.36% 75% 5.6287 12.07 67.94 75.60 89.87% 80% 6.0037 12.07 72.46 80.56 89.95% 100% 7.5037 12.06 90.49 100.55 90.00% 17/35 Electrical performance AN2852 The efficiency taken at 25%, 50%, 75% and 100% of rated load allows calculating the average efficiency required by the ENERGY STAR® specification. Table 3. Average efficiency for EPA Vin [Vrms] Average efficiency for EPA 115 87.44% 230 88.19% Table 4 shows the no-load consumption. The adapter has good values (about 300 mW at 230Vac), considering that it is a two-stage system with the PFC stage always on. Table 4. No-load consumption Vin [Vac] 90 115 135 180 230 264 Pin [W] 0.215 0.225 0.235 0.255 0.290 0.315 This adapter meets the two conditions required by ENERGY STAR® specification version 2.0 (average efficiency > 87% and no-load input power < 0.5 W) for an external power supply (EPS). Therefore this SMPS is EPA 2.0 compliant. Figure 16 shows the graph of the efficiency vs. output power while Figure 17 shows the graph of the input power vs. input voltage with no load applied. Figure 16. Efficiency vs. O/P power Efficiency 92.00% 90.00% 88.00% 86.00% 84.00% 82.00% 80.00% 78.00% 76.00% 74.00% 72.00% 70.00% 68.00% 66.00% 115Vac 230Vac 0 20 40 60 80 100 Output power [W] AM01831v1 18/35 AN2852 Electrical performance Figure 17. No-load consumption 0.350 Input power [W] 0.300 0.250 0.200 0.150 0.100 0.050 0.000 50 100 150 200 250 300 Input voltage [Vac] AM01832v1 Some measurements with low output loads were also taken, refer to Table 5 and Table 6. Table 5. Low-load efficiency at 115Vrms Pout [W] Iout [mA] Vout [V] Pin [W] Eff [%] 1.50 124.50 12.12 2.696 55.97% 1.00 82.50 12.12 1.883 53.10% 0.50 42.02 12.12 1.076 47.31% 0.25 21.05 12.11 0.654 38.98% Table 6. Low-load efficiency at 230Vrms Pout [W] Iout [mA] Vout [V] Pin [W] Eff [%] 1.50 124.50 12.12 2.598 58.08% 1.00 82.50 12.12 1.802 55.49% 0.50 42.02 12.12 1.087 46.83% 0.25 21.05 12.11 0.704 36.21% 19/35 Electrical performance 3.2 AN2852 Harmonic content measurement The front-end PFC stage provides the reduction of the mains harmonic, allowing meeting European EN61000-3-2 and Japanese JEIDA-MITI standards for class D equipment. Figure 18 and 19 show the harmonic contents of the mains current at full load. A measure has been done also with 75 W input power which is the lower limit for using harmonic reduction techniques. Figure 18. EN61000-3-2 measurements at full load Figure 19. JEIDA-MITI measurements at full load 10 1 Measurements @ 230Vac Full load Measurements @ 100Vac Full load EN61000-3-2 class D limits JEIDA-MITI class D limits 1 Harmonic current (A) Harmonic current (A) 0.1 0.01 0.1 0.01 0.001 0.001 0.0001 0.0001 1 3 5 7 1 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 3 5 7 Harmonic order (n) 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 Harmonic order (n) AM01833v1 AM01834v1 Figure 20. EN61000-3-2 measurements at 75 W Figure 21. JEIDA-MITI measurements at 75 W input input 1 1 Measurements @ 230Vac 75W in EN61000-3-2 class D limits Measurements @ 100Vac 75W in 0.1 Harmonic current (A) Harmonic current (A) 0.1 JEIDA-MITI class D limits 0.01 0.001 0.01 0.001 0.0001 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 Harmonic order (n) AM01835v1 20/35 0.0001 1 Harmonic order (n) AM01836v1 AN2852 Electrical performance To evaluate the performance of the PFC stage also, the PF and THD vs. input voltage graphs are shown in Figure 22 and 23 at full load and 75 W input power. Figure 22. PF vs. input voltage 1.000 0.975 0.950 0.925 PF 0.900 Full load 75 W in 0.875 0.850 80 120 160 200 240 280 Vin [Vrms] AM01837v1 Figure 23. THD vs. input voltage 9.00 8.00 7.00 6.00 5.00 THD [%] 4.00 3.00 Full load 75 W in 160 200 2.00 1.00 0.00 80 120 240 280 Vin [Vrms] AM01838v1 21/35 Thermal measurements 4 AN2852 Thermal measurements A thermal analysis of the board was performed using an IR camera, refer to Figure 24 and 25. Figure 24. Thermal map at 115Vac - full load 90.0 °C 81.9 73.8 65.6 57.5 49.4 41.3 33.1 25.0 AM01839v1 Figure 25. Thermal map at 230Vac - full load 90.0 °C 81.9 73.8 65.6 57.5 49.4 41.3 33.1 25.0 AM01840v1 Temperature of key components (Tamb = 25 °C, emissivity = 0.95 for all points) Table 7. 22/35 Point Reference T [°C] at 115Vac T [°C] at 230Vac A D1 (Input bridge) 49.5 39.5 B Q1 (PFC MOSFET) 46.4 37.9 C D4 (PFC diode) 56.8 49.1 D R6 (NTC) 55.9 47.1 E L2 (PFC coil) 38.1 35.7 F Q4 (AHB low-side MOSFET) 43.8 39.2 AN2852 Thermal measurements Table 7. Temperature of key components (Tamb = 25 °C, emissivity = 0.95 for all points) (continued) Point Reference T [°C] at 115Vac T [°C] at 230Vac G Q3 (AHB high side MOSFET) 40.2 39.3 H T1 (AHB transformer ferrite) 64.8 63.4 I T1 (AHB transformer winding) 81.2 80.1 J D13 (AHB output diode) 83.1 81.8 K D12 (AHB output diode) 73.7 72.8 L L3 (Output inductor) 58.7 57.9 23/35 Conducted noise measurements (pre-compliance test) 5 AN2852 Conducted noise measurements (pre-compliance test) Figure 26 and 27 show the conducted noise measurements performed at the two nominal voltages with peak detection and considering only the worst phase. Both measures are well below the average limit (taken from EN55022 CLASS B norm). Figure 26. CE peak measure at 115Vac and full load AM01841v1 Figure 27. CE peak measure at 230Vac and full load AM01842v1 24/35 AN2852 Bill of material 6 Bill of material Table 8. EVL6591-90WADP bill of materials Ref Value Description Manufacturer C1 470 NF Polypropylene X2 capacitor - R46 KI 3470--02 M Arcotronics C10 1N0 SMD ceramic capacitor X7R - 50 V AVX C11 10 NF SMD ceramic capacitor X7R - 50 V AVX C12 470 NF SMD ceramic capacitor X7R - 25 V AVX C13 1 µF SMD ceramic capacitor X7R - 25 V AVX C14 100 NF SMD ceramic capacitor X7R - 50 V AVX C15 22 µF Electrolytic capacitor YXF - 50 V Rubycon C16 1N0 SMD ceramic capacitor X7R - 50 V AVX C17 N.M. Electrolytic capacitor C2 2N2 Ceramic Y1 capacitor - DE1E3KX222M Murata C20 2N2 Ceramic Y1 capacitor - DE1E3KX222M Murata C21 2N2 Ceramic Y1 capacitor - DE1E3KX222M Murata C22 220 PF SMD ceramic capacitor NP0 - 50 V AVX C3 2N2 Ceramic Y1 capacitor - DE1E3KX222M Murata C39 100 NF SMD ceramic capacitor X7R - 50 V AVX C4 470 NF Polypropylene X2 capacitor - R46 KI 3470--02 M Arcotronics C40 10 NF Ceramic capacitor X7R - 50 V AVX C41 4N7 SMD ceramic capacitor X7R - 50 V AVX C42 100 NF SMD ceramic capacitor X7R - 50 V AVX C43 10 NF SMD ceramic capacitor X7R - 50 V AVX C44 220 NF Polypropylene capacitor - B32652A3224J EPCOS C45 220 PF SMD ceramic capacitor NP0 - 50 V AVX C46 1000 µF Electrolytic capacitor ZL - 25 V Rubycon C47 2.2 NF SMD ceramic capacitor X7R - 50 V AVX C48 6.8 NF SMD ceramic capacitor X7R - 50 V AVX C49 330 PF SMD ceramic capacitor NP0 - 50 V - 2% AVX C5 470 NF Polypropylene capacitor - PHE426KD6470JR06L2 EVOX-RIFA C50 100 NF SMD ceramic capacitor X7R - 50 V AVX C51 22 uF Electrolytic capacitor YXF - 50 V Rubycon C52 100 NF SMD ceramic capacitor X7R - 50 V AVX C53 N.M. SMD ceramic capacitor X7R - 50 V C54 1 uF SMD ceramic capacitor X7R - 25 V AVX 25/35 Bill of material Table 8. 26/35 AN2852 EVL6591-90WADP bill of materials (continued) Ref Value Description Manufacturer C55 N.M. SMD ceramic capacitor X7R - 50 V C56 100 NF SMD ceramic capacitor X7R - 50 V AVX C57 100 µF Electrolytic capacitor YXF - 35 V Rubycon C58 1N8 SMD ceramic capacitor X7R - 50 V AVX C59 470 PF SMD ceramic capacitor X7R - 50 V AVX C61 N.M. Electrolytic capacitor C62 N.M. Electrolytic capacitor C9 47 µF Electrolytic capacitor - 450 V - EEUED2W470 Panasonic D1 GBU6J Bridge rectifier Vishay D12 STPS16L40CT Power Schottky rectifier STMicroelectronics D13 STPS30100ST Power Schottky rectifier STMicroelectronics D20 N.M. Zener diode D21 1N4148 Diode D22 LL4148 SMD diode D23 LL4148 SMD diode D24 LL4148 SMD diode D25 BZV55-B13 Zener diode - 2% Vishay D26 STPS1L60A SMD Schottky diode STMicroelectronics D27 LL4148 SMD diode D28 BZV55-B11 Zener diode - 2% D29 LL4148 SMD diode D3 1N4005 Diode Vishay D4 STTH2L06 Ultrafast diode STMicroelectronics F1 T4 A PCB fuse TR5 Wickmann J1 IN connector Screw connector - MKDS 1,5/3-5.08 Phoenix Contact J2 OUT connector Screw connector - MKDS 1,5/2-5.08 Phoenix Contact JP9 N.M. Wire jumper L1 2x25 mH Input EMI filter - HF2826-253Y1R2-T01 TDK L2 700 µH PFC inductor - 1825.0001 Magnetica L3 3.3 µH Power inductor - PCV-0-332-10L Coilcraft Q1 STP12NM50FP Power MOSFET STMicroelectronics Q10 BC847C Small signal BJT Q11 BC847C Small signal BJT Q3 STP12NM50FP Power MOSFET STMicroelectronics Q4 STP12NM50FP Power MOSFET STMicroelectronics Vishay AN2852 Table 8. Bill of material EVL6591-90WADP bill of materials (continued) Ref Value Description Manufacturer Q9 N.M. Small signal BJT R1 1M0 SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R10 15 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R100 0R0 SMD film resistor - 1206 Vishay R101 0R0 SMD film resistor - 1206 Vishay R11 3M0 Film resistor - 1% - 100 ppm/°C - 0.4W Vishay R12 3M0 Film resistor - 1% - 100 ppm/°C - 0.4W Vishay R13 8.2 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R14 18 kΩ SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R15 150 kΩ SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R17 0R0 SMD film resistor - 1206 Vishay R18 56 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R19 56 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R2 1M2 SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R20 0R0 SMD film resistor - 1206 Vishay R21 27 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R22 0R47 Film resistor – 5% – 250 ppm/°C - 0.4W Vishay R23 0R47 Film resistor – 5% – 250 ppm/°C - 0.4W Vishay R24 1.8 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R25 4.7 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R26 240 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R27 470 SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R28 24K9 SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R29 100 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R3 680 kΩ Film resistor - 1% - 100 ppm/°C - 1206 Vishay R30 2K2 SMD film resistor - 1% - 100 ppm/°C - 1206 Vishay R46 100 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R53 0R0 SMD film resistor - 1206 Vishay R54 0R0 SMD film resistor - 1206 Vishay R55 0R0 SMD film resistor - 1206 Vishay R6 2R5 NTC resistor S237 - B57237S0259M000 EPCOS R69 N.M. SMD resistor - 0805 Vishay R7 680 kΩ Film resistor - 1% - 100 ppm/°C - 0.4 W Vishay R70 33 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R71 10 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay 27/35 Bill of material Table 8. 28/35 AN2852 EVL6591-90WADP bill of materials (continued) Ref Value Description Manufacturer R72 10 Ω SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R73 100 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R74 10 Ω SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R75 56 Ω SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R77 56 Ω SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R78 19K6 SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R79 100 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R8 680 kΩ Film resistor - 1% - 100 ppm/°C - 0.4 W Vishay R80 1K0 SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R81 0R82 SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R82 0R82 SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R83 6K8 SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R84 220 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R85 220 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R86 33 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R87 N.M. SMD resistor - 0805 Vishay R88 2K2 SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R89 100 kΩ SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R9 82 kΩ SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R90 0R0 SMD film resistor – 0805 Vishay R91 75 kΩ SMD film resistor - 5% - 250 ppm/°C - 0805 Vishay R93 3K3 SMD film resistor - 1% - 100 ppm/°C - 0805 Vishay R94 12 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R95 47 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R96 470 SMD film resistor - 1% - 100 ppm/°C - 1206 Vishay R97 N.M. SMD resistor - 1206 Vishay R98 220 Ω SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay R99 15 kΩ SMD film resistor - 5% - 250 ppm/°C - 1206 Vishay T1 Transformer AHB transformer 1754.0004 Magnetica U1 L6563 Advanced TM PFC controller STMicroelectronics U2 L6591 PWM controller for ZVS half-bridge STMicroelectronics U3 PC817 Optocoupler - PC817X1J000F Sharp U4 TS3431AILT SMD voltage reference - 1% STMicroelectronics U5 PC817 Optocoupler - PC817X1J000F Sharp AN2852 PFC coil specifications 7 PFC coil specifications 7.1 Note: ● Application type: consumer, IT ● Transformer type: open ● Coil former: vertical type, 6+6 pins ● Max. temp. rise: 45°C ● Max. operating ambient temp.: 60°C ● Mains insulation: N.A. Electrical characteristics 1 ● Converter topology: boost, transition mode ● Core type: RM14 - N87 or equivalent ● Min. operating frequency: 20 kHz ● Primary inductance: 700 µH 10% at 1 kHz - 0.25 V (see Note 1) ● Peak primary current: 3.5 Apk ● RMS primary current: 1.25 ARMS. measured between pins 3-5 Figure 28. Electrical diagram 8 3 PRIM AUX 10 5 AM01843v1 Table 9. Winding characteristics Pins Winding RMS current Nr. of turns Wire type 3–5 Primary 1.25 ARMS 53 Stranded 7 x Ø 0.28 mm – G2 (1) 0.05 ARMS 4 spaced Ø 0.28 mm – G2 8 – 10 AUX 1. Auxiliary winding is wound on top of primary winding 29/35 PFC coil specifications 7.2 AN2852 Mechanical aspect and pin numbering ● Maximum height from PCB: 22 mm ● Coil former type: vertical, 6+6 pins ● Pin distance: 5.08 mm ● Row distance: 35.56 mm ● Pins removed: # 1, 4, 6, 7, 9, 11, 12 ● External copper shield: bare, wound around the ferrite core including the windings and coil former. Height is 7 mm. Connected by a solid wire soldered to pin 10 ● Manufacturer: Magnetica ● P/N: 1825.0001. Figure 29. Bottom view 6 7 1 12 AM01844v1 30/35 AN2852 AHB transformer specifications 8 AHB transformer specifications 8.1 Note: ● Application type: consumer, IT ● Transformer type: open ● Coil former: horizontal type, 7+7 pins ● Max. temp. rise: 45°C ● Max. operating ambient temp.: 60°C ● Mains insulation: compliance with EN60950. Electrical characteristics ● Converter topology: asymmetrical half-bridge ● Core type: ETD34 - N87 or equivalent ● Operating frequency: 100 kHz ● Primary inductance: 400 µH 10% at 1 kHz - 0.25 V (see Note 1) ● Air gap: 2.32 mm on central leg ● Leakage inductance: 10 µH max. at 100 kHz - 0.25 V (see Note 2) ● Primary capacitance: 6 pF typ. (see Note 3) ● Max. peak primary current: 1.93 Apk ● RMS primary current: 0.75 ARMS 1 measured between pins 2-4 2 measured between pins 2-4 with secondaries and auxiliary windings shorted 3 calculated considering primary inductance and resonance frequency Figure 30. Electrical diagram 2 9 SEC. PRIM. 4 10 5 12 SEC. AUX 6 14 AM01845v1 31/35 AHB transformer specifications Table 10. Note: AN2852 Winding characteristics Pins Winding RMS current Nr. of turns Wire type 2–3 Primary A 0.75 ARMS 35 Ø 0.355 mm – G2 9 – 10 Secondary 1 3.81 ARMS 4 Stranded 90 x Ø 0.1 mm – G1 12 – 14 Secondary 2 6.57 ARMS 7 Stranded 135 x Ø 0.1 mm – G1 3–4 Primary B 0.75 ARMS 35 Ø 0.355 mm – G2 5–6 Auxiliary 0.05 ARMS 3 spaced Ø 0.355 mm – G2 Primaries A and B are in series Cover wires ends with silicon sleeve Figure 31. Windings position 3mm 3mm AUX PRIMARY - B COIL FORMER INSULATING TAPE SECONDARY 2 SECONDARY 1 PRIMARY- A 8.2 AM01846v1 Mechanical aspect and pin numbering ● Maximum height from PCB: 30 mm ● Coil former type: vertical, low profile, 7+7 pins, NORWE ETD34lr/h14/-1/rtg ● Pin distance: 5.08 mm ● Row distance: 25.4 mm ● Pin removed: # 7 ● Manufacturer: Magnetica ● P/N: 1754.0004 Figure 32. Top view 32/35 1 14 7 8 AM01847v1 AN2852 9 PCB layout PCB layout Figure 33. Topside silk screen AM01848v1 Figure 34. Bottomside silk screen AM01849v1 Figure 35. Copper traces (bottomside) AM01850v1 33/35 Revision history 10 AN2852 Revision history Table 11. 34/35 Document revision history Date Revision 28-Jan-2009 1 Changes Initial release AN2852 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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