FL7732 Single-Stage PFC Primary-Side-Regulation Offline LED Driver Features Description Cost-Effective Solution: No Input Bulk Capacitor or Feedback Circuitry Power Factor Correction This highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters. The proprietary topology, ® TRUECURRENT enables simplified circuit design for LED lighting applications. Accurate Constant-Current (CC) Control, Independent Online Voltage, Output Voltage, and Magnetizing Inductance Variation Linear Frequency Control Improves Efficiency and Simplifies Design Open-LED Protection Short-LED Protection Cycle-by-Cycle Current Limiting Over-Temperature Protection with Auto Restart Low Startup Current: 20 μA Low Operating Current: 5 mA VDD Under-Voltage Lockout (UVLO) Gate Output Maximum Voltage Clamped at 18 V SOP-8 Package Application Voltage Range: 80 VAC ~ 308 VAC By using single-stage topology with primary-side regulation, a LED lighting board can be implemented with few external components and minimized cost. No input bulk capacitor or feedback circuitry is required. To implement good power factor and low THD, constant on-time control is utilized with an external capacitor connected to the COMI pin. Precise constant-current control regulates accurate output current versus changes in input voltage and output voltage. The operating frequency is proportionally adjusted by the output voltage to guarantee DCM operation with higher efficiency and simpler design. FL7732 provides open-LED, short-LED, and overtemperature protection features. The current limit level is automatically reduced to minimize output current and protect external components in a short-LED condition. The FL7732 controller is available in an 8-pin SmallOutline Package (SOP). Applications LED Lighting System Ordering Information Part Number Operating Temperature Range Package Packing Method FL7732M_F116 -40°C to +125°C 8-Lead, Small Outline Integrated Circuit Package (SOIC) Tape & Reel © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver October 2012 Figure 1. Typical Application Internal Block Diagram Figure 2. © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Application Diagram Functional Block Diagram www.fairchildsemi.com 2 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 (M=SOP) M: Manufacture Flow Code Figure 3. Top Mark Pin Configuration Figure 4. Pin Configuration Pin Definitions Pin # Name Description 1 CS 2 GATE PWM Signal Output. This pin uses the internal totem-pole output driver to drive the power MOSFET. 3 GND Ground 4 VDD Power Supply. IC operating current and MOSFET driving current are supplied using this pin. 5 NC No Connect 6 VS Voltage Sense. This pin detects the output voltage information and discharge time for maximum frequency control and constant current regulation. This pin is connected to an auxiliary winding of the transformer via resistors of the divider. 7 COMI Constant Current Loop Compensation. This pin is connected to a capacitor between the COMI and GND pin for compensation current loop gain. 8 GND Ground Current Sense. This pin connects a current-sense resistor to detect the MOSFET current for the output-current regulation in constant-current regulation. © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Marking Information 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. (1,2) Max. Unit 30 V VVDD DC Supply Voltage VVS VS Pin Voltage -0.3 7 V VCS CS Pin Input Voltage -0.3 7 V VCOMI COMI Pin Input Voltage -0.3 7 V VGATE GATE Pin Input Voltage -0.3 30 V PD Power Dissipation (TA＜50°C) 633 mW ΘJA Thermal Resistance (Junction-to-Air) 158 °C /W ΘJC Thermal Resistance (Junction-to-Case) 39 °C /W Maximum Junction Temperature 150 °C TJ TSTG TL Storage Temperature Range -55 Lead Temperature (Soldering 10 s) 150 °C 260 °C Notes: 1. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. 2. All voltage values, except differential voltages, are given with respect to the GND pin. © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Absolute Maximum Ratings www.fairchildsemi.com 4 VDD=15 V and TA=25°C, unless otherwise specified. Symbol Parameter Condition Min. Typ. Max. Unit 14.5 16.0 17.5 V 6.75 7.75 8.75 V 3 4 5 mA 2 20 μA 23.5 25.0 V VDD Section VDD-ON Turn-On Threshold Voltage VDD-OFF Turn-Off Threshold Voltage IDD-OP Operating Current IDD-ST Startup Current VOVP VDD Over-Voltage-Protection Level At Maximum Frequency CL=1 nF VDD=VDD-ON – 0.16 V 22.0 Gate Section VOL Output Voltage Low VDD=20 V, IGATE=-1 mA VOH Output Voltage High VDD=10 V, IGATE=+1 mA Peak Sourcing Current VDD=10 ~ 20 V Isource Isink 1.5 5 V V 60 mA 180 mA Peak Sinking Current VDD=10 ~ 20 V tr Rising Time CL=1 nF 100 150 200 ns tf Falling Time CL=1 nF 20 60 100 ns 12 15 18 V VCLAMP Output Clamp Voltage Oscillator Section fMAX-CC Maximum Frequency in CC VDD=10 V, 20 V 60 65 70 kHz fMIN-CC Minimum Frequency in CC VDD=10 V, 20 V 21.0 23.5 26.0 kHz VSMAX-CC VS for Maximum Frequency in CC f=fMAX-2 kHz 2.25 2.35 2.45 V VSMIN-CC VS for Minimum Frequency in CC f=fMIN +2 kHz 0.55 0.85 1.15 V tON(MAX) Maximum Turn-On Time 12 14 16 μs 2.475 2.500 2.525 V 2.38 2.43 2.48 V Current-Sense Section VRV Reference Voltage VCCR EAI Voltage for CC Regulation tLEB Leading-Edge Blanking Time tMIN Minimum On Time in CC tPD VCS=0.44 V VCOMI=0 V Propagation Delay to GATE 50 300 ns 600 ns 100 150 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Electrical Characteristics ns tDIS-BNK tDIS Blanking Time of VS 1.5 μs IVS-BNK VS Current for VS Blanking 100 μA 85 μmho Current-Error-Amplifier Section Gm Transconductance ICOMI-SINK COMI Sink Current VEAI=3 V, VCOMI=5 V COMI Source Current 25 38 μA 38 μA VEAI=2 V, VCOMI=0 V 25 VCOMI-HGH COMI High Voltage VEAI=2 V 4.9 VCOMI-LOW COMI Low Voltage VEAI=3 V ICOMI-SOURCE V 0.1 V Continued on the following page… © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com 5 VDD=15 V and TA=25°C, unless otherwise specified. Symbol Parameter Condition Min. Typ. Max. Unit VCS Threshold Voltage for OCP 0.60 0.67 0.74 V VLowOCP VCS Threshold Voltage for Low OCP 0.13 0.18 0.23 V VLowOCP-EN VS Threshold Voltage to Enable Low OCP Level 0.4 V VLowOCP-DIS VS Threshold Voltage to Disable Low OCP Level 0.6 V Over-Current Protection Section VOCP Over-Temperature Protection Section TOTP TOTP-HYS Threshold Temperature for OTP(3) 140 Restart Junction Temperature Hysteresis 150 10 160 o C o C Note: 3. If over-temperature protection is activated, the power system enters Auto-Recovery Mode and output is disabled. Device operation above the maximum junction temperature is NOT guaranteed. OTP is guaranteed by design. © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Electrical Characteristics (Continued) www.fairchildsemi.com 6 1.5 1.3 1.3 Normalized to 25 °C Normalized to 25 °C 1.5 1.1 0.9 0.7 1.1 0.9 0.7 0.5 0.5 -40 -30 -15 0 25 50 75 85 100 -40 125 -30 -15 0 VDD-ON vs. Temperature Figure 6. 1.5 1.5 1.3 1.3 Normalized to 25 °C Normalized to 25 °C Figure 5. 1.1 0.9 0.7 50 75 85 100 125 VDD-OFF vs. Temperature 1.1 0.9 0.7 0.5 0.5 -40 -30 -15 0 25 50 75 85 100 -40 125 -30 -15 0 IDD-OP vs. Temperature Figure 7. 25 50 75 85 100 125 Temp [°C] Temp [°C] Figure 8. 1.5 1.5 1.3 1.3 Normalized to 25 °C Normalized to 25 °C 25 Temp [°C] Temp [°C] 1.1 0.9 0.7 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Typical Performance Characteristics VOVP vs. Temperature 1.1 0.9 0.7 0.5 0.5 -40 -30 -15 0 25 50 75 85 100 -40 125 -30 -15 Figure 9. fMAX_CC vs. Temperature © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 0 25 50 75 85 100 125 Temp [°C] Temp [°C] Figure 10. fMIN_CC vs. Temperature www.fairchildsemi.com 7 1.5 1.3 1.3 Normalized to 25 °C Normalized to 25 °C 1.5 1.1 0.9 0.7 0.5 1.1 0.9 0.7 0.5 -40 -30 -15 0 25 50 75 85 100 125 -40 -30 -15 0 Temp [°C] VCCR vs. Temperature Figure 12. 1.5 1.5 1.3 1.3 Normalized to 25 °C Normalized to 25 °C Figure 11. 25 50 75 85 100 125 Temp [°C] 1.1 0.9 0.7 0.5 VVVR vs. Temperature 1.1 0.9 0.7 0.5 -40 -30 -15 0 25 50 75 85 100 125 -40 -30 -15 Temp [°C] Figure 13. 25 50 75 85 100 Temp [°C] VOCP vs. Temperature © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 0 Figure 14. VOCP_Low vs. Temperature 125 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Typical Performance Characteristics (Continued) www.fairchildsemi.com 8 ® TRUECURRENT technique, constant-current output can be precisely controlled. FL7732 is AC-DC PWM controller for LED lighting ® applications. TRUECURRENT techniques regulate accurate LED current independent or input voltage, output voltage, and magnetizing inductance variations. The linear frequency control in the oscillator reduces conduction loss and maintains DCM operation in the wide range of output voltage, which implements high power factor correction in a single-stage flyback topology. A variety of protections, such as short/openLED protection, over-temperature protection, and cycleby-cycle current limitation stabilize system operation and protect external components. PFC and THD In a conventional boost converter, Boundary Conduction Mode (BCM) is generally used to keep input current inphase with input voltage for PF and THD. In flyback/buck boost topology, constant turn-on time and constant frequency in Discontinuous Conduction Mode (DCM) can implement high PF and low THD, as shown in Figure 16. Constant turn-on time is maintained by the internal error amplifier and a large external capacitor (typically over 1 µF) at the COMI pin. Constant frequency and DCM operation are managed by linear frequency control. Startup Powering at startup is slow due to the low feedback loop bandwidth in PFC converter. To boost powering during startup, an internal oscillator counts 12 ms to define Startup Mode. During Startup Mode, turn-on time is determined by Current-Mode control with a 0.2 VCS voltage limit and transconductance becomes 14 times larger, as shown in Figure 15. After startup, turn-on time is controlled by Voltage Mode using COMI voltage and error amplifier transconductance is reduced to 85 μmho. Figure 16. Input Current and Switching Linear Frequency Control FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Functional Description As mentioned above, DCM should be guaranteed for high power factor in flyback topology. To maintain DCM across the wide range of output voltage, frequency is linearly adjusted by output voltage in linear frequency control. Output voltage is detected by the auxiliary winding and the resistive divider connected to the VS pin, as shown in Figure 17. Figure 15. Startup Sequence Constant-Current Regulation The output current can be estimated using the peak drain current and inductor current discharge time since output current is same as the average of the diode current in steady state. The peak value of the drain current is determined by the CS pin and the inductor discharge time (tDIS) is sensed by tDIS detector. By using three points of information (peak drain current, inductor discharging time, and operating switching period); ® TRUECURRENT calculation block estimates output current. The output of the calculation is compared with an internal precise reference to generate an error voltage (VCOMI), which determines turn-on time in Voltage-Mode control. With Fairchild’s innovative © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 Figure 17. Linear Frequency Control www.fairchildsemi.com 9 nV O Lm t t DIS n 3 V 4 O Lm 4 t 3 4 t DIS 3 n 3 V 5 Lm O 5 t DIS 3 5 t 3 Figure 20. Figure 18. Primary and Secondary Current Open-LED Protection BCM Control FL7732 protects external components, such as diode and capacitor, at secondary side in open-LED condition. During switch-off, the VDD capacitor is charged up to the auxiliary winding voltage, which is applied as the reflected output voltage. Because the VDD voltage has output voltage information, the internal voltage comparator on the VDD pin can trigger output OverVoltage Protection (OVP), as shown in Figure 21. When at least one LED is open-circuited, output load impedance becomes very high and output capacitor is quickly charged up to VOVP x NS / NA Then switching is shut down and the VDD block goes into Hiccup Mode until the open-LED condition is removed, as shown in Figure 22. The end of secondary diode conduction time is possibly over a switching period set by linear frequency control. In this case, FL7732 doesn’t allow CCM and the operation mode changes from DCM to BCM. Therefore, magnetizing inductance can be largely designed to add BCM for better efficiency if PF and THD meet specification with enough margin. Short-LED Protection In case of a short-LED condition, the switching MOSFET and secondary diode are stressed by the high powering current. However, FL7732 changes the OCP level in a short-LED condition. When VS voltage is lower than 0.4 V, OCP level becomes 0.2 V from 0.7 V, as shown in Figure 19, so powering is limited and external components current stress is reduced. Figure 19. Waveforms in Short-LED Condition FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Figure 20 shows operational waveforms in short-LED condition. Output voltage is quickly lowered to 0V right after a short-LED event. Then the reflected auxiliary voltage is also 0 V, making VS less than 0.4 V. 0.2 V OCP level limits primary-side current and VDD hiccups up and down between UVLO hysteresis. When output voltage decreases, secondary diode conduction time is increased and the linear frequency control lengthens the switching period, which retains DCM operation in the wide output voltage range, as shown in Figure 18. The frequency control lowers the primary rms current with better power efficiency in the full-load condition. Internal OCP Block © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com 10 The turn-on and turn-off thresholds are fixed internally at 16 V and 7.5 V, respectively. During startup, the VDD capacitor must be charged to 16 V through the startup resistor to enable the FL7732. The VDD capacitor continues to supply VDD until power can be delivered from the auxiliary winding of the main transformer. VDD must not drop below 7.5 V during this startup process. This UVLO hysteresis window ensures that the VDD capacitor is adequate to supply VDD during startup. Over-Temperature Protection (OTP) Figure 21. Figure 22. The FL7732 has a built-in temperature-sensing circuit to shut down PWM output if the junction temperature exceeds 150°C. While PWM output is shut down, the VDD voltage gradually drops to the UVLO voltage. Some of the internal circuits are shut down and VDD gradually starts increasing again. When VDD reaches 16 V, all the internal circuits start operating. If the junction temperature is still higher than 140°C, the PWM controller is shut down immediately. Internal OVP Block FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Under-Voltage Lockout (UVLO) Waveforms in Open-LED Condition © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com 11 5.00 4.80 A 0.65 3.81 5 8 B 1.75 6.20 5.80 PIN ONE INDICATOR 4.00 3.80 1 5.60 4 1.27 (0.33) 1.27 0.25 C B A LAND PATTERN RECOMMENDATION SEE DETAIL A 0.25 0.10 1.75 MAX 0.25 0.19 C 0.51 0.33 0.10 C OPTION A - BEVEL EDGE 0.50 x 45° 0.25 R0.10 GAGE PLANE R0.10 OPTION B - NO BEVEL EDGE 0.36 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver Physical Dimensions NOTES: UNLESS OTHERWISE SPECIFIED 8° 0° 0.90 0.40 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 23. 8-Lead, Small Outline Integrated Circuit Package (SOIC) 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/. © 2012 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com 11 FL7732 — Single-Stage PFC Primary-Side-Regulation Offline LED Driver © 2011 Fairchild Semiconductor Corporation FL7732 • Rev. 1.0.6 www.fairchildsemi.com 13