FAN6862

FAN6862 — Highly Integrated Green-Mode PWM Controller January 2010 FAN6862 Highly Integrated Green-Mode PWM Controller Features Low Startup Current: 8µA Low Operating Current in Green Mode: 3mA Peak-Current Mode Operation with Cycle-by-Cycle Current Limiting PWM Frequency Continuously Decreasing with Burst Mode at Light Loads VDD Over-Voltage Protection (OVP) Constant Output Power Limit (Full AC Input Range) Internal Latch Circuit for OVP, OTP Fixed PWM Frequency (65KHz) with Frequency Hopping Feedback Open-Loop Protection with 56ms Delay Soft Start Time: 4ms 400mA Driving Capability Description A highly integrated PWM controller, FAN6862 provides several features to enhance the performance of flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode, which completely shuts off PWM output. Output restarts just before the supply voltage drops below the UVLO lower limit. This green-mode function enables power supplies to meet international power conservation requirements. The FAN6862 is designed for SMPS and integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters. The built-in synchronized slope compensation is proprietary sawtooth compensation for constant output power limit over universal AC input range. The gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. Other protection functions include VDD over-voltage protection and over-temperature protection. For overtemperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When VDD OVP or OTP is activated, an internal latch circuit latches off the controller. Applications General-purpose switch-mode power supplies and flyback power converters, including: Power Adapters Open-Frame SMPS SMPS with Surge-Current Output, such as for Printers, Scanners, and Motor Drivers Part Number FAN6862TY FAN6862NY OVP Latch Latch OTP Latch Latch OLP Auto Restart Auto Restart Ordering Information Part Number FAN6862TY FAN6862NY Operating Temperature Range -40 to +105°C -40 to +105°C Eco Status Green Green Package 6-Pin SSOT-6 8-Pin Dual In-Line Package (DIP) Packing Method Tape & Reel Tube For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com FAN6862 — Highly Integrated Green-Mode PWM Controller Typical Application Figure 1. Typical Application Block Diagram Figure 2. Block Diagram © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 2 FAN6862 — Highly Integrated Green-Mode PWM Controller Marking Information ABx: TT: : _ _ _: ABD: FAN6862TY Wafer Lot Code Year Code Week Code F – Fairchild Logo Z – Plant Code X – 1-Digit Year Code Y – 1-Digit Week Code TT – 2-Digit Die Run Code T – Package Type (N:DIP) P – Y: Green Package M – Manufacture Flow Code Figure 3. Top Mark Pin Configuration Figure 4. SSOT-6 Figure 5. DIP-8 Pin Definitions Pin # DIP8 8 Pin # SSOT-6 1 Name GND Ground. Description 7 2 FB Feedback. The FB pin provides the output voltage regulation signal. It provides feedback to the internal PWM comparator, so that the PWM comparator can control the duty cycle. This pin also provide for OLP: if VFB is larger than the trigger level and delays for a long time, the controller stops and restarts. No Connect Pin Temperature Detection. An external NTC thermistor is connected from this pin to GND for over-temperature protection. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT pin drops below a threshold, PWM output is disabled. Current Sense. This pin senses the voltage across a resistor. When the voltage reaches the internal threshold, PWM output is disabled. This activates over-current protection. This pin also provides current amplitude information for current-mode control. No Connect Pin Power Supply. Driver Output. The totem-pole output driver for driving the power MOSFET. 6 NC 5 3 RT 4 3 2 1 4 SENSE NC 5 6 VDD GATE © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 3 FAN6862 — Highly Integrated Green-Mode PWM Controller Absolute Maximum Ratings Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. All voltage values, except differential voltages, are given with respect to GND pin. Symbol VDD VL PD ΘJC TJ TSTG TL ESD Supply Voltage Parameter Input Voltage to FB, SENSE, RT Pin Power Dissipation at TA51% Duty=0% Duty=DCYMAX 360 0.5 0.44 0.273 4 Oscillator Section VFB>VFB-N VFB≥VFB-N VFB=VFB-G VFB≥VFB-N VFB=VFB-G 62 65 ±4.2 ±2.9 4.4 11.5 22.5 2.2 2.1 1.7 VDD=11.5V to 20V TA= -40 to +105°C 0 0.02 2.00 2 ms ms kHz V V V % % 68 kHz fOSC Normal PWM Frequency Hopping Range Hopping Range Hopping Period 1 Hopping Period 3 Green Mode Minimum Frequency FB Threshold Voltage For Frequency Reduction FB Voltage at fOSC-G FB Threshold Voltage for Zero Duty Frequency Variation vs. VDD Deviation Frequency Variation vs. Temperature Deviation thop-1 thop-3 fOSC-G VFB-N VFB-G VFB-ZDC fDV fDT Continued on the following page… © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 5 FAN6862 — Highly Integrated Green-Mode PWM Controller Electrical Characteristics (Continued) VDD = 15V and TA = 25°C unless otherwise noted. Symbol PWM Output Section DCYMAX VOL VOH tR tF VCLAMP IRT VOTP tDOTP VOTP2 tDOTP2 Parameter Maximum Duty Cycle Output Voltage Low Output Voltage High Rising Time Falling Time Gate Output Clamping Voltage Output Current of RT Pin Threshold Voltage for Over-Temperature Protection Over-Temperature Debounce Time 2 Threshold Voltage for Over-Temperature Protection 2 nd nd Test Condition Min. Typ. 70 Max. Unit % VDD=15V, IO=50mA VDD=8V, IO=50mA CL=1nF CL=1nF VDD=20V 15.0 6 150 35 16.5 100 TA=25°C VFB=VFB-N VFB=VFB-G TA=25°C 0.60 0.95 1.00 17 51 0.70 100 1.5 200 18.0 V V ns ns V μA Over-Temperature Protection (OTP) Section 1.05 V ms 0.75 V μs Over-Temperature Debounce Time © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 6 FAN6862 — Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics 17 9.5 16.6 9.1 16.2 VDD-OFF (V) -40 -30 -15 0 25 50 75 85 100 125 VDD-ON (V) 8.7 15.8 8.3 15.4 7.9 15 7.5 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 6. Turn-on Threshold Voltage (VDD-ON) vs. Temperature Figure 7. Turn-off Threshold Voltage (VDD-OFF) vs. Temperature 4.5 26 4.1 25.6 IDD-OP (mA) 3.7 VDD-OVP (V) -40 -30 -15 0 25 50 75 85 100 125 25.2 3.3 24.8 2.9 24.4 2.5 24 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 8. Operating Current (IDD-OP) vs. Temperature Figure 9. VDD Over-Voltage Protection (VDD-OVP) vs. Temperature 68 67 66 2.2 2.12 fOSC (KHz) VFB-N (V) 2.04 65 64 63 62 -40 -30 -15 0 25 50 75 85 100 125 1.96 1.88 1.8 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 10. Center Frequency (fOSC) vs. Temperature Figure 11. FB Threshold Voltage for Frequency Reduction (VFB-N) vs. Temperature © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 7 FAN6862 — Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics (Continued) 2.2 4.9 2.12 4.8 2.04 VFB-OLP (V) -40 -30 -15 0 25 50 75 85 100 125 VFB-G (V) 4.7 1.96 4.6 1.88 4.5 1.8 4.4 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 12. FB Voltage at fOSC-G (VFB-G) vs. Temperature Figure 13. Threshold Voltage for Open-Loop Protection (VFB-OLP) vs. Temperature 59 58 57 56 55 54 53 -40 -30 -15 0 25 50 75 85 100 125 0.6 0.56 tD-OLP (ms) VSTHFL (V) 0.52 0.48 0.44 0.4 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 14. Open-Loop Protection Delay Time (tD-OLP) vs. Temperature Figure 15. Flat Threshold Voltage for Current Limit (VSTHFL) vs. Temperature 0.55 5 0.51 4 0.47 tSOFT-START (ms) -40 -30 -15 0 25 50 75 85 100 125 VSTHVA (V) 3 0.43 2 0.39 1 0.35 0 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 16. Valley Threshold Voltage for Current Limit (VSTHVA) vs. Temperature Figure 17. Period during Startup (tSOFT-START) vs. Temperature © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 8 FAN6862 — Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics (Continued) 72 200 71 180 DCYMAX (%) 69 tR (ns) -40 -30 -15 0 25 50 75 85 100 125 70 160 140 68 120 67 100 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 18. Maximum Duty Cycle (DCYMAX) vs. Temperature Figure 19. Rising Time (tR) vs. Temperature 50 120 40 112 20 IRT (μA) -40 -30 -15 0 25 50 75 85 100 125 tF (ns) 30 104 96 10 88 0 80 -40 -30 -15 0 25 50 75 85 100 125 Temperature (ºC) Temperature (ºC) Figure 20. Falling Time (tF) vs. Temperature Figure 21. Output Current of RT Pin (IRT) vs. Temperature © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 9 FAN6862 — Highly Integrated Green-Mode PWM Controller Operation Description Startup Operation Figure 22 shows a typical startup circuit and transformer auxiliary winding for a FAN6862 application. Before FAN6862 begins switching operation, it consumes only startup current (typically 8μA) and the current supplied through the startup resistor charges the VDD capacitor (CDD). When VDD reaches turn-on voltage of 16V (VDD-ON), FAN6862 begins switching and the current consumed increases to 3mA. Then, the power required is supplied from the transformer auxiliary winding. The large hysteresis of VDD (8.5V) provides more holdup time, which allows using a small capacitor for VDD. The startup resistor is typically connected to AC line for a fast reset of latch protection. Figure 23. PWM Frequency Vo VFB VFB.ZDC (1.7V) Ids Figure 22. Startup Circuit Switching Disabled Switching Disabled Figure 24. Burst Mode Operation Green-Mode Operation The FAN6862 uses feedback voltage (VFB) as an indicator of the output load and modulates the PWM frequency, as shown in Figure 23, such that the switching frequency decreases as load decreases. In heavy load conditions, the switching frequency is 65KHz. Once VFB decreases below VFB-N (2.2V), the PWM frequency starts to linearly decrease from 65KHz to 22.5kHz to reduce the switching losses. As VFB decreases below VFB-G (2.1V), the switching frequency is fixed at 22.5kHz and FAN6862 enters “deep” green mode, where the operating current decreases to 2.5mA (maximum), further reducing the standby power consumption. As VFB decreases below VFB-ZDC (1.7V), FAN6862 enters burst-mode operation. When VFB drops below VFB-ZDC, FAN6862 stops switching and the output voltage starts to drop, which causes the feedback voltage to rise. Once VFB rises above VFB-ZDC, switching resumes. Burst mode alternately enables and disables switching, thereby reducing switching loss in standby mode, as shown in Figure 24. Frequency Hopping EMI reduction is accomplished by frequency hopping, which spreads the energy over a wider frequency range than the bandwidth measured by the EMI test equipment. An internal frequency hopping circuit changes the switching frequency between 60.8kHz and 69.2kHz with a period of 4.4ms, as shown in Figure 25. Figure 25. Frequency Hopping © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 10 FAN6862 — Highly Integrated Green-Mode PWM Controller Protections Self-protective functions include VDD Over-Voltage Protection (OVP), Open-Loop / Overload Protection (OLP), Over-Current Protection (OCP), Short-Circuit Protection, and Over-Temperature Protection (OTP). OLP, OCP, and SCP are auto-restart mode protections; while OVP and OTP are latch-mode protections. Auto-Restart Mode Protection: Once a fault condition is detected, switching is terminated and the MOSFET remains off. This causes VDD to fall because no more power is delivered from auxiliary winding. When VDD falls to VDD-OFF (8.5V), the protection is reset and the operating current reduces to startup current, which causes VDD to rise. FAN6862 resumes normal operation when VDD reaches VDD-ON (16V). In this manner, the auto-restart can alternately enable and disable the switching of the MOSFET until the fault condition is eliminated (see Figure 26). Latch-Mode Protection: Once this protection is triggered, switching is terminated and the MOSFET remains off. The latch is reset only when VDD is discharged below 4V by unplugging AC power line. Open-Loop / Over-Load Protection (OLP) W hen the upper branch of the voltage divider for the shunt regulator (KA431 shown) is broken, as shown in Figure 27, no current flows through the opto-coupler transistor, which pulls up the feedback voltage to 5.2V. When the feedback voltage is above 4.6V longer than 56ms, OLP is triggered. This protection is also triggered when the SMPS output drops below the nominal value longer than 56ms due to the overload condition. Figure 27. OLP Operation VDD Over-Voltage Protection (OVP) VDD over-voltage protection prevents IC damage caused by over voltage on the VDD pin. The OVP is triggered when VDD reaches 25V. A debounce time (typically 30µs) prevents false triggering by switching noise. Over-Temperature Protection (OTP) The OTP circuit is composed of current source and voltage comparators. Typically, an NTC thermistor is connected between the RT and GND pins. Once the voltage of this pin drops below a threshold of 1.0V, PWM output is disabled after tDOTP debounce time. If this pin drops below 0.7V, it triggers the latch-off protection immediately after tDOTP2 debounce time. Figure 26. Auto Restart Operation Over-Current Protection (OCP) FAN6862 has over-current protection thresholds. It is for pulse-by-pulse current limit, which turns off MOSFET for the remainder of the switching cycle when the sensing voltage of MOSFET drain current reaches the threshold. The other threshold is for the over-current protection, which shuts down the MOSFET gate when the sensing voltage of MOSFET drain current is above the threshold longer than the shutdown delay (56ms). © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 11 FAN6862 — Highly Integrated Green-Mode PWM Controller Constant Output Power Limit FAN6862 has saw-limiter for pulse-by-pulse current limit, which guarantees almost constant power limit over different line voltages of universal input range. The conventional pulse-by-pulse current limiting scheme has a constant threshold for current limit comparator, which results in a higher power limit for high line voltage. FAN6862 has a sawtooth current limit threshold that increases progressively within a switching cycle, which provides lower current limit for high line and makes the actual power limit level almost constant over different line voltages of universal input range, as shown in Figure 28. Leading-Edge Blanking (LEB) Each time the power MOSFET is switched on, a turn-on spike occurs across the sense-resistor caused by primary-side capacitance and secondary-side rectifier reverse recovery. To avoid premature termination of the switching pulse, a leading-edge blanking time is built in. During this blanking period (360ns), the PWM comparator is disabled and cannot switch off the gate driver. Thus, RC filter with a small RC time constant is enough for current sensing. Figure 29. Current Sense R-C Filter Figure 28. Sawtooth Current Limiter Soft-Start The FAN6862 has an internal soft-start circuit that increases pulse-by-pulse current-limit comparator inverting input voltage slowly after it starts. The typical soft-start time is 4ms. The pulsewidth to the power MOSFET is progressively increased to establish the correct working conditions for transformers, rectifier diodes, and capacitors. The voltage on the output capacitors is progressively increased with the intention of smoothly establishing the required output voltage. It also helps prevent transformer saturation and reduces the stress on the secondary diode during startup. © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 12 FAN6862 — Highly Integrated Green-Mode PWM Controller Applications Information R1 R 1.5M/1206 2 3 L2 TR N-0211 1 4 R2 R 1.5M/1206 4 3 L1 F1 3.15A NTC1 SCK053 2 3 BD1 BD 2A/600V 1 R7 R4 R 100K/1206 R 750K/1206 2 C4 C82uF/450V C3 YC470p/400V R5 R 750K/1206 22 Q1 MOS 6A/600V 1 R 0R/0805 3 R17 + 1 C5 C 472pF/1KV N2 3 D1 N3 11 D2 D 1N4007 -1 10 2 RM 8 飛線 L1 900uH 4 N1 1 TR 1 2 M1 MOV +1 6 飛線 C1 R3 C 102P/1206 R 47R/1206 N5 2 1 N4 L3 1 2 C 680uF/25V 3 1 10uH LED1 C 330uF/25V + C6 + C11 1 R10 R 1K/1206 SGN 2 VO VO C2 XC 0.33uF/275V 1 N1 D1 20A/100V 7 D3 D 1N4007 R6 R 100/1206 R8 R 0R22/1W 1 R9 R 0R/0805 D4 1 D 1N4148 + + C9 C/10uF/50V 2 U1 GND 1 FB 2 C7 C 102P/0805 RT 3 GND FB RT GATE VDD SENSE 6 GATE 5 VDD 4 SENSE C12 C/4.7uF/50V C8 C 471p/0805 R11 FAN6862 R 5.6K/0805 NTC2 TTC 100K R13 R 560/0805 R12 R/100/1206 4 U3 1 PC 817 R16 R 39K/1206 U2 TL431 R15 R 10K/0805 A K2 C10 R14 C 0.1uF/0805 R 10K/0805 3 R Figure 30. 36W (12V/3A) Application Circuit BOM Designator BD1 D1 D2, D3 D4 F1 NTC1 NTC2 L1 L2 L3 TR1 M1 LED1 C1 C2 C3 C4 C5 C6, C11 C7 Part Type 2KBP06M 2A/600V Y2010DN 20A/100V 1N4007 1N4148 Fuse 3.15A/250V NTC Thermistor SCK053 NTC Thermistor TTC 100KΩ 900µH 10mH 10µH RM-8 400µH VZ 9G LED CC 1nF XC 0.33µF/275V YC 470pF/400V EC 82µF/400V CC 4.7nF/1KV EC 680µF/25V CC 1nF C8 C9 C10 C12 Designator Part Type CC 470pF/50V EC 10µF/50V CC 0.1µF/50V EC 4.7µF/50V R 1.5MΩ (option) R 47Ω R 750KΩ (option) R 100Ω R 100KΩ R 0.22Ω / 1W R 0Ω R 1KΩ R 5.6KΩ R 560Ω R 10KΩ R 39KΩ IC FAN6862 TL431 PC-817 MOSFET 6A/600V www.fairchildsemi.com R1, R2 R3 R4, R5 R6, R12 R7 R8 R9 R10 R11 R13 R14, R15 R16 U1 U2 U3 Q1 13 © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 FAN6862 — Highly Integrated Green-Mode PWM Controller Physical Dimensions Figure 31. 6-Pin, SUPERSOT6 “SSOT-6”, JEDEC MO-193, 1.6mm Wide Package Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/. © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 14 FAN6862 — Highly Integrated Green-Mode PWM Controller Physical Dimensions 9.83 9.00 6.67 6.096 8.255 7.61 5.08 MAX 3.683 3.20 7.62 0.33 MIN (0.56) 2.54 3.60 3.00 0.56 0.355 1.65 1.27 7.62 0.356 0.20 9.957 7.87 NOTES: UNLESS OTHERWISE SPECIFIED A) THIS PACKAGE CONFORMS TO JEDEC MS-001 VARIATION BA B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS ARE EXCLUSIVE OF BURRS, MOLD FLASH, AND TIE BAR EXTRUSIONS. D) DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994 E) DRAWING FILENAME AND REVSION: MKT-N08FREV2. Figure 32. 8-Pin Dual In-Line Package (DIP) Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 15 FAN6862 — Highly Integrated Green-Mode PWM Controller © 2009 Fairchild Semiconductor Corporation FAN6862 • Rev. 1.0.2 www.fairchildsemi.com 16