FAN6751MR Highly-Integrated Green-Mode PWM Controller Features Description High-Voltage Startup The highly integrated FAN6751 series of PWM controllers provides several features to enhance the performance of flyback converters. Internal OTP Sensor with Hysteresis Brownout Protection with Hysteresis Low Operating Current: 4mA Linearly Decreasing PWM Frequency to 18KHz Fixed PWM Frequency: 65KHz Peak-current-mode Control Cycle-by-cycle Current Limiting Leading-edge Blanking (LEB) Synchronized Slope Compensation Internal Open-loop Protection GATE Output Maximum Voltage Clamp: 18V VDD Under-Voltage Lockout (UVLO) To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency at light-load conditions. To avoid acoustic-noise problems, the minimum PWM frequency is set above 18KHz. This green-mode function enables the power supply to meet international power conservation requirements. With the internal high-voltage startup circuitry, the power loss due to bleeding resistors is also eliminated. To further reduce power consumption, FAN6751 is manufactured using the BiCMOS process, which allows an operating current of only 4mA. Built-in synchronized slope compensation achieves stable peak-current-mode control. The proprietary, external line compensation ensures constant output power limit over a wide AC input voltage range, from 90VAC to 264VAC. VDD Over-Voltage Protection (OVP) Internal Recovery Circuit (OVP, OLP) Internal Sense Short-Circuit Protection External Constant Power Limit (Full AC Input Range) Built-in 5ms Soft-Start Function Built-in VIN Pin Pull HIGH (> 4.7V) Recovery Function for Second-Side Output OVP FAN6751 provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open-loop or output short-circuit failure occur. PWM output is disabled until VDD drops below the UVLO lower limit, when the controller starts up again. As long as VDD exceeds ~26V, the internal OVP circuit is triggered. FAN6751 is available in an 8-pin SOP package. Applications General-purpose switch-mode power supplies and flyback power converters, including: Power Adapters Open-frame SMPS Ordering Information Part Number Operating Temperature Range FAN6751MRMY -40°C to +105°C Eco Status Green Package Packing Method 8-Lead, Small Outline Package (SOP-8) Tape & Reel For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com FAN6751MR — Highly-Integrated Green-Mode PWM Controller September 2008 Figure 1. Typical Application FAN6751MR — Highly-Integrated Green-Mode PWM Controller Application Diagram Internal Block Diagram Figure 2. Functional Block Diagram © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 2 FAN6751MR — Highly-Integrated Green-Mode PWM Controller Marking Information F: Fairchild logo Z: Plant code X: 1 digit year code Y: 1 digit week code TT: 2 digits die run code T: Package type (N:DIP, M:SOP) P: Y=Green package M: Manufacture flow code ZXYTT 6751MR TPM Figure 3. Top Mark Pin Configuration SOP-8 GND 1 8 GATE FB 2 7 VDD NC 3 6 SENSE HV 4 5 VIN Figure 4. Pin Configuration (Top View) Pin Definitions Pin # Name Description 1 GND 2 FB The signal from the external compensation circuit is fed into this pin. The PWM duty cycle is determined in response to the signal on this pin and the current-sense signal on the SENSE pin. 3 NC No connection. 4 HV For startup, this pin is pulled high to the line input or bulk capacitor via resistors. 5 VIN Line-voltage detection. The line-voltage detection is used for brownout protection with hysteresis. Constant output power limit over universal AC input range is also achieved using this VIN pin. It is suggested to add a low pass filter to filter out line ripple on bulk capacitor. VIN pulling high triggers latch protection. 6 SENSE Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. 7 VDD Power supply. The internal protection circuit disables PWM output as long as VDD exceeds the OVP trigger point. 8 GATE Ground. The totem-pole output driver. Soft-driving waveform is implemented for improved EMI. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 3 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. Symbol Parameter Min. Max. Unit (1, 2) VDD DC Supply Voltage 30 V VFB FB Pin Input Voltage -0.3 7.0 V SENSE Pin Input Voltage -0.3 7.0 V VVIN VIN Pin Input Voltage -0.3 7.0 V VHV HV Pin Input Voltage 500 V PD Power Dissipation (TA＜50°C) 400 mW ΘJA Thermal Resistance, Junction-to-Air 141 °C/W TJ Operating Junction Temperature -40 +150 °C Storage Temperature Range -55 +150 °C +260 °C VSENSE TSTG TL ESD Lead Temperature (Wave Soldering or IR, 10 Seconds) Electrostatic Discharge Capability, Human Body Model: JESD22-A114 All pins except HV pin 4 kV Electrostatic Discharge Capability, Machine Model: JESD22-A115 All pins except HV pin 200 V Notes: 1. All voltage values, except differential voltages, are given with respect to the network ground terminal. 2. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 FAN6751MR — Highly-Integrated Green-Mode PWM Controller Absolute Maximum Ratings www.fairchildsemi.com 4 VDD=15V, TA=25°C, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Units 22 V V VDD Section VOP Continuously Operating Voltage VDD-ON Start Threshold Voltage VDD-OFF Minimum Operating Voltage 15.5 16.5 17.5 9.5 10.5 11.5 V 30 µA 4 5 mA 30 70 90 µA IDD-ST Startup Current VDD-ON – 0.16V IDD-OP Operating Supply Current VDD=15V, GATE Open IDD-OLP Internal Sink Current VTH-OLP+0.1V VTH-OLP IDD-OLP Off Voltage 6.5 7.5 8.0 V VDD-OVP VDD Over-Voltage Protection 25 26 27 V tD-VDDOVP VDD Over-Voltage Protection Debounce Time 75 130 200 µs 2.0 3.5 mA 1 20 µA 62 65 68 KHz 14 18 22 KHz HV Section IHV IHV-LC Supply Current Drawn from HV Pin VAC=90V (VDC=120V), VDD=10µF, VDD=0V Leakage Current after Startup HV=500V, VDD=VDD-OFF+1V Oscillator Section fOSC fOSC-G Frequency in Nominal Mode Center Frequency Green-Mode Frequency fDV Frequency Variation vs. VDD Deviation VDD=11V to 22V 5 % fDT Frequency Variation vs. Temperature Deviation TA=-40 to 85°C 5 % FAN6751MR — Highly-Integrated Green-Mode PWM Controller Electrical Characteristics VIN Section VIN-OFF PWM Turn-off Threshold Voltage 0.65 0.70 0.75 V VIN-ON PWM Turn-on Threshold Voltage VIN-OFF+ 0.20 VIN-OFF+ 0.22 VIN-OFF+ 0.24 V VIN-LATCH PWM Latch-off Threshold Voltage 4.5 4.7 4.9 V TVIN-LATCH PWM Latch-off Debounce Time 60 100 140 µs Continued on following page… © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 5 VDD=15V, TA=25°C, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Units 1/4.5 1/4.0 1/3.5 V/V 7 kΩ Feedback Input Section AV Input Voltage to Current-Sense Attenuation ZFB Input Impedance 4 VFB-OPEN Output High Voltage VFB-OLP FB Open-loop Trigger Level FB Pin Open 5.5 V 5.0 5.2 5.4 V tD-OLP Delay Time of FB Pin Open-loop Protection 56 ms VFB-N Green-Mode Entry FB Voltage 2.1 V VFB-G Green-Mode Ending FB Voltage 1.6 V Zero Duty-Cycle Input Voltage 1.1 V 12 KΩ VFB-ZDC Current-Sense Section ZSENSE Input Impedance VTH-P at VIN=1V Threshold Voltage for Current Limit VIN=1V 0.80 0.83 0.86 V VTH-P at VIN=3V Threshold Voltage for Current Limit VIN=3V 0.67 0.70 0.73 V 100 200 ns tPD tLEB Delay to Output Leading-Edge Blanking Time 230 280 330 ns VS-SCP Threshold Voltage for SENSE ShortCircuit Protection 0.10 0.15 0.20 V tD-SSCP Delay Time for SENSE Short-Circuit Protection VSENSE<0.15V 100 150 200 µs Period During Soft-Startup Time Startup Time 4.5 5.0 5.5 ms TSS FAN6751MR — Highly-Integrated Green-Mode PWM Controller Electrical Characteristics PWM Frequency fOSC fOSC-G VFB-ZDC VFB-G VFB-N VFB Figure 5. VFB vs. PWM Frequency © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 6 VDD=15V, TA=25°C, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Units GATE Section DCYMAX Maximum Duty Cycle VGATE-L Gate Low Voltage VDD=15V, IO=50mA VGATE-H Gate High Voltage VDD=12V, IO=50mA 8 tr Gate Rising Time VDD=15V, CL=1nF 150 250 350 ns tf Gate Falling Time VDD=15V, CL=1nF 30 50 90 ns Gate Source Current VDD=15V, GATE=6V 250 Gate Output Clamping Voltage VDD=22V IGATESOURCE VGATECLAMP 75 % 1.5 V V mA V 18 Over-Temperature Protection Section (OTP) TOTP TRestart Protection Junction Temperature Restart Junction Temperature (3) (4) +135 °C TOTP-25 °C Notes: 3. When activated, the output is disabled and the latch is turned off. 4. The threshold temperature for enabling the output again and resetting the latch, after over-temperature protection has been activated. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 FAN6751MR — Highly-Integrated Green-Mode PWM Controller Electrical Characteristics www.fairchildsemi.com 7 Figure 6. Startup Current (IDD-ST) vs. Temperature Figure 7. Operation Supply Current (IDD-OP) vs. Temperature Figure 8. Start Threshold Voltage (VDD-ON) vs. Temperature Figure 9. Minimum Operating Voltage (VDD-OFF) vs. Temperature Figure 10. Supply Current Drawn from HV Pin (IHV) vs. Temperature Figure 11. HV Pin Leakage Current After Startup (IHV-LC) vs. Temperature © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 FAN6751MR — Highly-Integrated Green-Mode PWM Controller Typical Performance Characteristics www.fairchildsemi.com 8 Figure 12. Frequency in Nominal Mode (fOSC) vs. Temperature © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 Figure 13. Maximum Duty Cycle (DCYMAX) vs. Temperature FAN6751MR — Highly-Integrated Green-Mode PWM Controller Typical Performance Characteristics (Continued) www.fairchildsemi.com 9 Startup Current Gate Output / Soft Driving For startup, the HV pin is connected to the line input (1N4007 / 100KΩ recommended) or bulk capacitor through a resistor, RHV. Typical startup current drawn from pin HV is 2mA and charges the hold-up capacitor through the diode and resistor. When the VDD capacitor level reaches VDD-ON, the startup current switches off. At this moment, the VDD capacitor only supplies the FAN6751 to keep the VDD before the auxiliary winding of the main transformer to provide the operating current. The BiCMOS output stage is a fast totem-pole gate driver. Cross conduction has been avoided to minimize heat dissipation, increase efficiency, and enhance reliability. The output driver is clamped by an internal 18V Zener diode to protect power MOSFET transistors against undesirable gate over voltage. A soft-driving waveform is implemented to minimize EMI. Soft-Start For many applications, it is necessary to minimize the inrush current at startup. The built-in 5ms soft-start circuit significantly reduces the startup current spike and output voltage overshoot. Operating Current Operating current is around 4mA. The low operating current enables better efficiency and reduces the requirement of VDD hold-up capacitance. Built-in Slope Compensation Green-Mode Operation The sensed voltage across the current-sense resistor is used for peak-current-mode control and pulse-by-pulse current limiting. Built-in slope compensation improves stability and prevents sub-harmonic oscillation. FAN6751 inserts a synchronized positive-going ramp at every switching cycle. The proprietary green-mode function provides off-time modulation to reduce the switching frequency in the light-load and no-load conditions. The on time is limited for better abnormal or brownout protection. VFB, which is derived from the voltage feedback loop, is taken as the reference. Once VFB is lower than the threshold voltage, switching frequency is continuously decreased to the minimum green-mode frequency of around 18KHz. Constant Output Power Limit For constant output power limit over universal inputvoltage range, the peak-current threshold is adjusted by the voltage of the VIN pin. Since the VIN pin is connected to the rectified AC input line voltage through the resistive divider, a higher line voltage generates a higher VIN voltage. The threshold voltage decreases as the VIN voltage increases, making the maximum output power at high-line input voltage equal to that at low-line input. The value of R-C network should not be so large it affects the power limit (shown as Figure 14). Usually, R and C are less than 100Ω and 470pF, respectively. Current Sensing / PWM Current Limiting Peak-current-mode control is utilized to regulate output voltage and provide pulse-by-pulse current limiting. The switch current is detected by a sense resistor into the SENSE pin. The PWM duty cycle is determined by this current sense signal and VFB, the feedback voltage. When the voltage on SENSE pin reaches around VCOMP=(VFB–1.2)/4, a switch cycle is terminated immediately. VCOMP is internally clamped to a variable voltage around 0.85V for output power limit. FAN6751MR — Highly-Integrated Green-Mode PWM Controller Functional Description Leading-Edge Blanking (LEB) Each time the power MOSFET is switched on, a turn-on spike occurs on the sense-resistor. To avoid premature termination of the switching pulse, a leading-edge blanking time is built in. During this blanking period, the current-limit comparator is disabled and it cannot switch off the gate driver. SG5841 Gate Blanking Circuit Sense Under-Voltage Lockout (UVLO) The turn-on and turn-off thresholds are fixed internally at 16.5V and 10.5V respectively. During startup, the hold-up capacitor must be charged to 16.5V through the startup resistor to enable the IC. The hold-up capacitor continues to supply VDD before the energy can be delivered from auxiliary winding of the main transformer. VDD must not drop below 10.5V during this process. This UVLO hysteresis window ensures that hold-up capacitor is adequate to supply VDD during startup. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 Figure 14. Current Sense R-C Filter www.fairchildsemi.com 10 Limited Power Control VDD over-voltage protection is built-in to prevent damage due to abnormal conditions. Once the VDD voltage is over the over-voltage protection voltage (VDDOVP), and lasts for tD-VDDOVP, the PWM pulses are disabled until the VDD voltage drops below the UVLO, then starts again. Over-voltage conditions are usually caused by open feedback loops. The FB voltage increases every time the output of the power supply is shorted or overloaded. If the FB voltage remains higher than a built-in threshold for longer than tD-OLP, PWM output is turned off. As PWM output is turned off, VDD begins decreasing. When VDD goes below the turn-off threshold (~10.5V), the controller is totally shut down. VDD is charged up to the turn-on threshold voltage of 16.5V through the startup resistor until PWM output is restarted. This protection feature continues as long as the overloading condition persists. This prevents the power supply from overheating due to overloading conditions. Brownout Protection Since the VIN pin is connected through a resistive divider to the rectified AC input line voltage, it can also be used for brownout protection. If the VIN voltage is less than 0.7V, the PWM output is shut off. If the VIN voltage over 0.92V, the PWM output is turned on again. The hysteresis window for on/off is around 0.22V. The brownout voltage setting is determined by the potential divider formed with RUpper and RLower. To calculate the resistors: VIN = RLower × VAC , (unit = V ) RLower + RUpper Noise Immunity Noise on the current sense or control signal may cause significant pulse-width jitter, particularly in continuousconduction mode. Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. Avoiding long PCB traces and component leads, locating compensation and filter components near the FAN6751, and increasing the power MOS gate resistance improve performance. (1) Thermal-Overload Protection Thermal-overload protection limits total power dissipation. When the junction temperature exceeds TJ = +135°C, the thermal sensor signals the shutdown logic and turns off most of the internal circuitry. The thermal sensor turns internal circuitry on again after the IC’s junction temperature drops by 25°C. Thermaloverload protection is designed to protect the FAN6751 in the event of a fault condition. For continual operation, do not exceed the absolute maximum junction temperature rating of TJ = +150°C. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 FAN6751MR — Highly-Integrated Green-Mode PWM Controller VDD Over-Voltage Protection (OVP) www.fairchildsemi.com 11 5.00 4.80 A 0.65 3.81 5 8 B 6.20 5.80 PIN ONE INDICATOR 1.75 4.00 3.80 1 5.60 4 1.27 (0.33) 0.25 M 1.27 C B A LAND PATTERN RECOMMENDATION 0.25 0.10 SEE DETAIL A 1.75 MAX 0.25 0.19 C 0.10 0.51 0.33 0.50 x 45° 0.25 R0.10 FAN6751MR — Highly-Integrated Green-Mode PWM Controller Physical Dimensions C OPTION A - BEVEL EDGE GAGE PLANE R0.10 OPTION B - NO BEVEL EDGE 0.36 NOTES: UNLESS OTHERWISE SPECIFIED 8° 0° 0.90 0.406 A) THIS PACKAGE CONFORMS TO JEDEC MS-012, VARIATION AA, ISSUE C, B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS DO NOT INCLUDE MOLD FLASH OR BURRS. D) LANDPATTERN STANDARD: SOIC127P600X175-8M. E) DRAWING FILENAME: M08AREV13 SEATING PLANE (1.04) DETAIL A SCALE: 2:1 Figure 15. 8-Pin, Small Outline Package (SOP) 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/. © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 12 FAN6751MR — Highly-Integrated Green-Mode PWM Controller © 2008 Fairchild Semiconductor Corporation FAN6751MR • Rev. 1.0.0 www.fairchildsemi.com 13