APPLICATION NOTE (R) 12V-65W WIDE-RANGE INPUT MAINS ADAPTER USING THE L6566B Introduction This note describes the characteristics and the features of a 65 W reference board, wide-range input mains, AC-DC adapter using the L6566B controller. The peculiarities of this design are the low standby input consumption (<200mW@265Vinac), low cost and small size. Figure 1: EVL6566B-65W Adapter demo-board August 2005 1/11 APPLICATION NOTE Main characteristics and circuit description * * * * * * * * * UNIVERSAL INPUT MAINS RANGE: OUTPUT VOLTAGE: MAINS HARMONICS: ST-BY MAINS CONSUMPTION: OVERALL EFFICIENCY: EMI: SAFETY: DIMENSIONS: PCB: 90/264Vac - Frequency 45 / 65Hz 12V@5.42A continuous operation Acc. to EN61000-3-2 Class-D TYP. 0.2 W @265Vac TYP. 83 % @ 230Vac According to EN55022-Class-B According to EN60950 51 x 109.5mm - 25mm maximum height Double layer mixed PTH/SMD technology Circuit description The topology of this converter is the classical Flyback working in continuous and discontinuous conduction mode at fixed frequency. The controller, the new L6566B, is an extremely versatile current mode primary controller ICs. The nominal switching frequency, 80 KHz, has been chosen to get a compromise between the transformer size and the converter efficiency. The input EMI filter is a classical Pi-filter, 2-cells for differential and common mode noise filtering. A NTC limits the inrush current produced by the capacitor charging at plug-in. The MOSFET is a standard and inexpensive 600V-0.75max, TO220FP, needing a heat sink. The transformer is a layer type, using a standard ferrite type EER28L. The reflected voltage is 90 V, providing enough room for the leakage inductance voltage spike with still margin for reliability of the MOSFET. The network D3, R11A, R11B, R11C and C11 clamps the peak of the leakage inductance voltage spike. At power on, the L6566B has an internal high-voltage current source sourcing a current from the DC bus and charging the capacitors C2 and C3 connected to the Vcc pin. Once the turn-on threshold is reached, the HV current source is turned-off. This allows saving power dissipation during normal operation and provides very good circuit efficiency during standby. The divider R4, R10, R45 and R46 senses the input voltage and it is dedicated to the Brownout and Voltage feedforward pins. The AC_OK pin (#16) is dedicated to the brownout protection. When the voltage on this pin is below the internal threshold (0.45V typ.) the IC is disabled. The VFF pin (pin#15), is dedicated to limit the maximum power deliverable according to the input voltage of the converter. As previously mentioned, the control system is Current Mode, so the current flowing in the transformer primary winding is sensed by R7B, R7C and R7D then it is fed into the CS (pin #7). For over voltage protection (OVP), the transformer auxiliary winding is connected to ZCD (pin #11) via the R3 and R9 divider. In case of feedback network failures or open loop operation, if the voltage on ZCD pin rises over its threshold the L6566B is latched. After OVP detection and the following latch, the controller operation can be resumed by disconnecting the mains plug. The switching frequency is programmed by OSC (pin #13) connected to the resistor R18. Furthermore the L6566B has the Soft Start (pin #14), Disable (pin #8) and 5 Volt Reference voltage VREF (pin #10) available. The output rectifier is a dual common-cathode Schottky diode, Q201. A snubber, made up of R19A, R19B and C12, damps the oscillation produced by the diode Q201. A small LC filter has been added on the output in order to reduce the high frequency ripple. The output regulation makes use of a dedicated control IC, the TSM1014, embedding a refernce and an error ampliifer. The output signal of the error amplifier drives the optocoupler OPTO4 transferring the information to primary side with the required insulation of the secondary side. 2/11 APPLICATION NOTE Figure 2: Electrical diagram 3/11 APPLICATION NOTE Test Results Efficiency measurements at full load In table 1 the converter overall efficiency measurement at nominal load (5.42 A) and different input voltage are reported. In table 2 the efficiency measurements according to the Energy Star regulation are taken. The average values at both the nominal input mains voltages are reported too, in bold. In all conditions the efficiency measurements are compliant with the current energy saving rules. Table 1: Efficiency measurements at full load Vinac EFFICIENCY 90 [V] 80.47 % 115 [V] 82.52 % (*) 230 [V] 83.91 % (*) 265 [V] 83.64 % (*) Compliant to CEC, EU-COC, regulation Table 2: Energy star ENERGY STAR EFFICIENCY Vinac 1.35 A 2.7 A 4.1 A 5.42 A (25%) (50%) (75%) (100%) 115 [V] 84.24% 84.46% 83.53% 82.52% 83.69% 230 [V] 82.77% 83.92% 84.34% 83.91% 83.74% Average 4/11 APPLICATION NOTE Functional Check Full load operation In figure 3 and 4 some waveforms during steady state operation are reported. It is possible also to note which the working switching frequency is 79 kHz. Figure 3: EVL6566B-65W Waveforms @115V-60Hz - Full load Figure 4: EVL6566B-65W Waveforms @230V-50Hz - Full load CH1: CH2: CH3: CH1: CH2: CH3: Q101 Drain voltage Q101 Gate voltage VCC Q7 Drain voltage Q7 Gate voltage VCC Stand by and No-load operation In figures 5 and 6, some waveforms during no-load condition are captured. As visible, the L6566B works in burst mode achieving the best efficiency. In the pictures even the Vcc value is captured. It is shown that even in worst condition, at maximum input voltage (265Vac), the L6566B is powered correctly with good margin with respect to its maximum turn-off threshold (8 V). This prevents from spurious turn off that could affect the output voltage stability. Figure 5: EVL6566B-65W Burst mode @90V-60Hz - No load operation Figure 6: EVL6566B-65W Burst mode @265V-60Hz - No load operation CH1: CH2: CH1: CH2: Q101 Drain voltage L6566B Vcc (pin #5) Q101 Drain voltage L6566B Vcc (pin #5) 5/11 APPLICATION NOTE In Table 3, the input power consumption at no load is reported: as visible, thanks to the L6566B stand-by functions, the input power remains always below 200mW. Table 3: Input power at no load vs. mains voltage Vin [Vrms] 90 115 230 265 Input power [W] 0.066 0.077 (*) 0.162 (*) 0.200 (*) Compliant to CEC, EU-COC, Energy Star Over Current and Short Circuit Protection (OCP) In figure 7 and 8 it is shown the circuit behaviour in case of an output short circuit: as visible the L6566B stops switching and the Vcc voltage drops till the UVLO threshold. The controller reduces its consumption so increasing the duration of the Off-time and avoiding high dissipation on the secondary side in short conditions. The restart tentative is repeated indefinitely, until the short is removed. Figure 7: EVAL6566B-65W Short circuit at 230Vac-50Hz - Full load Figure 8: EVAL6566B-65W Short circuit at 230Vac-50Hz - No load CH1: CH2: CH1: CH2: Q101 Drain voltage L6566B Vcc (pin #5) Q101 Drain voltage L6566B Vcc (pin #5) 6/11 APPLICATION NOTE Open Loop Protection (OVP) In figure 9 and 10 it is shown the circuit behaviour simulating an open loop condition by opening R17. Once the voltage on ZCD pin connected to the transformer auxiliary winding by a divider rises over its threshold, the L6566B stops switching. To prevent from unlatching the circuit by the Vcc drop, the internal HV current source of the L6566B is periodically reactivated to keep the Vcc voltage above the turn-off threshold. The IC consumption is reduced too. To resume the normal operation the input mains has to be re-cycled. In pictures 9 and 10 the output voltage during Open loop operation has been captured. As visible comparing the two pictures, thanks to the L6566B internal circuitry, the output voltage value in this condition is almost independent by the load. Figure 9: EVAL6566B-65W Open loop at 230Vac-50Hz - Full load Figure 10: EVAL6566B-65W Open loop at 230Vac-50Hz - No load CH1: CH2: CH3: CH2: CH3: Q101 Drain voltage L6566B Vcc (pin #5) VOUT L6566B Vcc (pin #5) VOUT Start up behaviour In the pictures below, the start up behaviour is shown in two different load conditions. The output voltage rising is monotonic and doesn't show any overshoot Figure 11: EVAL6566B-65W Start up behaviour at 230Vac-50Hz - Full load Figure 12: EVAL6566B-65W Start up behaviour at 230Vac-50Hz - No load CH1: CH2: CH3: CH1: CH2: CH3: L6566B Soft Start (pin#14) L6566B Vcc (pin #5) VOUT L6566B Soft Start (pin#14) L6566B Vcc (pin #5) VOUT 7/11 APPLICATION NOTE Bill of material Table 4: EVAL6566B-65W: Bill of Material Reference Part name BR1 C2 C3 C4 C5 C7 C8 C9 C10 C11 C12 C13 C16 C18 C19 C214 CN1 CX1 CX2 CY3 D1 D2 D3 D105 F1 HS1 HS2 L1 LF1 LF2 OPTO4 Q101 Q201 R1 R1A R1B R2 R3 R4 R6 R7 R7B R7C R7D R8 R9 R10 DB 4A 600V 100uF - 25V 100nF 470u - 25V 470u - 25V 470u - 16V 2.2nF 100nF 100nF 3nF - 1kV 470pF 0R0 1nF 100nF 120u - 400V 330nF CON2-IN 100nF 100nF 3.3nF LL4148 STTH108 STTH108 LL4148 FUSE 2A HEAT-SINK HEAT-SINK 2.2uH CHOKE-D15x10 CHOKE-D15x10 SFH617A-4_0 STP10NK60ZFP STPS20H100FP 33R 510K 510K 200K 10K 12K 100K 15K 1R2 1R2 1R2 470R 36K 62K Description SINGLE PHASE BRIDGE RECTIFIER 25V - ALUMINIUM ELCAP - 105C 50V CERCAP - GENERAL PURPOSE 25V - ALUMINIUM ELCAP - 105C 25V - ALUMINIUM ELCAP - 105C 16V - ALUMINIUM ELCAP - 105C 50V CERCAP - GENERAL PURPOSE 50V CERCAP - GENERAL PURPOSE 50V CERCAP - GENERAL PURPOSE 100V CERCAP - GENERAL PURPOSE SMD FILM RES - 1/8W - 5% - 250ppm/C 50V CERCAP - GENERAL PURPOSE 50V CERCAP - GENERAL PURPOSE 400V - ALUMINIUM ELCAP - 85C 50V CERCAP - GENERAL PURPOSE TWO WIRES CONNECTOR X2 - FLM CAP - 250V X2 - FLM CAP - 250V Y1 - SAFETY CAP. - 250V FAST SWITCHING DIODE HIGH VOLTAGE ULTRAFAST RECTIFIER HIGH VOLTAGE ULTRAFAST RECTIFIER FAST SWITCHING DIODE FUSE T2A HEAT-SINK HEAT-SINK 2u2 - RADIAL INDUCTOR - 6A INPUT EMI FILTER INPUT EMI FILTER OPTOCOUPLER N-CHANNEL POWER MOSFET COMMON CATHODE SCHOTKY DIODE SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/4W - 1% - 100ppm/C SMD FILM RES - 1/4W - 1% - 100ppm/C SMD FILM RES - 1/4W - 1% - 100ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C 0805 0805 0805 0805 1206 0805 0805 0805 0805 SOD-80 DO41 DO41 SOD-80 TO-220FP TO-220FP 0805 1206 1206 0805 0805 0805 0805 0805 1206 1206 1206 0805 0805 0805 8/11 APPLICATION NOTE R11A R11B R11C R14 R15 R17 R18 R19 R19A R19B R22 R23 R45 R46 T1 TH1 U1 U5 U4 300K 300K 300K 10R 12K 23K4 27K 6K2 100R 100R 2K7 22K 3M 3M ERL28-12PIN NTC 10R TSM1014AIDT L6566B TS2431ILT SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/8W - 1% - 100ppm/C SMD FILM RES - 1/8W - 1% - 100ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/8W - 1% - 100ppm/C SMD FILM RES - 1/8W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C SMD FILM RES - 1/4W - 5% - 250ppm/C POWER TRANSFORMER NTC RESISTOR LOW CONSUMPTION CC/CV CONTROLLER ADVANCED PWM CONTROLLER VOLTAGE REFERENCE 1206 1206 1206 0805 0805 0805 0805 0805 1206 1206 0805 0805 1206 1206 MINI SO-8 SO-16 SOT-23 9/11 APPLICATION NOTE TRANSFORMER specification PIN DISTANCE: 5.08 mm PIN ROW DISTANCE: 30.5 mm PINS #7, 8, 12 are removed - Pin 3, 9 are for insertion polarity key. MECHANICAL ASPECT AND PIN NUMBERING 30.5 mm 5.08 mm 1 12 2 11 3 10 28.5 mm 4 9 5 8 6 7 37.5 mm TOP VIEW Transformer specification General description and characteristics * * * * APPLICATION TYPE: TRANSFORMER TYPE: WINDING TYPE COIL FORMER: Consumer, Home Appliance Open Layer Horizontal type, 6+6 pins * * MAX. TEMP. RISE: MAX. OPERATING AMBIENT TEMP.: 45 C 60 C Electrical characteristics * * CONVERTER TOPOLOGY: CORE TYPE: Flyback, CCM/DCM Mode EER28L - PC40 * * * * MIN. OPERATING FREQUENCY: TYPICAL OPERATING FREQ: PRIMARY INDUCTANCE: LEAKAGE INDUCTANCE: 80 KHz 480 H 5% @1KHz - 0.25V 5.12 H @ 100KHz - 0.25V [1] [1]-[2] [1]: Measured between pins 4-6 [2]: Measured between pins 4-6 with all secondary windings shorted 10/11 APPLICATION NOTE Electrical diagram and winding characteristics PINS: WINDING NUMBER OF TURNS WIRE TYPE 6-2 PRIMARY - B 28 G2- 2 x 0.45 mm 21mm x 0.1mm Copper Shielding connected to pin 5 10-11 12V 8 G2 - 4 x 0.4 mm 21mm x 0.1mm Copper Shielding connected to pin 5 2-4 PRIMARY - A 28 G2 - 2 x 0.45 mm 1-5 AUX 12 G2 - 0.3 mm PRIMARY A 12 V SHIELDING PRIMARY B AUX COIL FORMER NOTE: PRIMARIES A & B ARE IN SERIES 11/11