FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converters Features Description Variable Frequency Control with 50% Duty Cycle for Half-Bridge Resonant Converter Topology High Efficiency through Zero Voltage Switching (ZVS) Internal UniFETTM with Fast-Recovery Body Diode Fixed Dead Time (350ns) Optimized for MOSFETs Up to 300kHz Operating Frequency Auto-Restart Operation for All Protections with External LVCC Protection Functions: Over-Voltage Protection (OVP), Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), Internal Thermal Shutdown (TSD) Applications PDP and LCD TVs Desktop PCs and Servers Adapters Telecom Power Supplies The FSFR-XS series includes highly integrated power switches designed for high-efficiency half-bridge resonant converters. Offering everything necessary to build a reliable and robust resonant converter, the FSFRXS series simplifies designs while improving productivity and performance. The FSFR-XS series combines power MOSFETs with fast-recovery type body diodes, a highside gate-drive circuit, an accurate current controlled oscillator, frequency limit circuit, soft-start, and built-in protection functions. The high-side gate-drive circuit has common-mode noise cancellation capability, which guarantees stable operation with excellent noise immunity. The fast-recovery body diode of the MOSFETs improves reliability against abnormal operation conditions, while minimizing the effect of reverse recovery. Using the zero-voltage-switching (ZVS) technique dramatically reduces the switching losses and significantly improves efficiency. The ZVS also reduces the switching noise noticeably, which allows a smallsized Electromagnetic Interference (EMI) filter. The FSFR-XS series can be applied to resonant converter topologies such as series resonant, parallel resonant, and LLC resonant converters. Related Resources AN4151 -- Half-bridge LLC Resonant Converter Design TM Using FSFR-Series Fairchild Power Switch (FPS ) Ordering Information Part Number Package Operating Junction Temperature FSFR2100XS FSFR1800XS FSFR1700XS 9-SIP FSFR1600XS -40 to +130C FSFR2100XSL FSFR1800XSL FSFR1700XSL 9-SIP L-Forming FSFR1600XSL RDS(ON_MAX) Maximum Output Power without Heatsink (1,2) (VIN=350~400V) Maximum Output Power with Heatsink (1,2) (VIN=350~400V) 0.51 180W 400W 0.95 120W 260W 1.25 100W 200W 1.55 80W 160W 0.51 180W 400W 0.95 120W 260W 1.25 100W 200W 1.55 80W 160W Notes: 1. The junction temperature can limit the maximum output power. 2. Maximum practical continuous power in an open-frame design at 50C ambient. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter October 2010 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Application Circuit Diagram Figure 1. Typical Application Circuit (LLC Resonant Half-Bridge Converter) Block Diagram Figure 2. Internal Block Diagram (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 2 Figure 3. Package Diagram Pin Definitions Pin # Name Description 1 VDL This is the drain of the high-side MOSFET, typically connected to the input DC link voltage. 2 AR This pin is for discharging the external soft-start capacitor when any protections are triggered. When the voltage of this pin drops to 0.2V, all protections are reset and the controller starts to operate again. 3 RT This pin programs the switching frequency. Typically, an opto-coupler is connected to control the switching frequency for the output voltage regulation. 4 CS This pin senses the current flowing through the low-side MOSFET. Typically, negative voltage is applied on this pin. 5 SG This pin is the control ground. 6 PG This pin is the power ground. This pin is connected to the source of the low-side MOSFET. 7 LVCC This pin is the supply voltage of the control IC. 8 NC 9 HVCC No connection. This is the supply voltage of the high-side gate-drive circuit IC. 10 VCTR This is the drain of the low-side MOSFET. Typically, a transformer is connected to this pin. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 3 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Pin Configuration 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. TA=25C unless otherwise specified. Symbol VDS LVCC Parameter Min. Maximum Drain-to-Source Voltage (VDL-VCTR and VCTR-PG) Low-Side Supply Voltage Max. Unit 500 V -0.3 25.0 V -0.3 25.0 V High-Side Floating Supply Voltage -0.3 525.0 V VAR Auto-Restart Pin Input Voltage -0.3 LVCC V VCS Current-Sense (CS) Pin Input Voltage -5.0 1.0 V VRT RT Pin Input Voltage -0.3 5.0 V 50 V/ns HVCC to VCTR High-Side VCC Pin to Low-Side Drain Voltage HVCC dVCTR/dt PD TJ TSTG Allowable Low-Side MOSFET Drain Voltage Slew Rate Total Power Dissipation (3) Maximum Junction Temperature FSFR2100XS/L 12.0 FSFR1800XS/L 11.7 FSFR1700XS/L 11.6 FSFR1600XS/L 11.5 (4) W +150 (4) Recommended Operating Junction Temperature -40 +130 Storage Temperature Range -55 +150 C C MOSFET Section VDGR Drain Gate Voltage (RGS=1M) VGS Gate Source (GND) Voltage IDM Drain Current Pulsed (5) 500 30 FSFR2100XS/L 32 FSFR1800XS/L 23 FSFR1700XS/L 20 FSFR1600XS/L 18 FSFR2100XS/L FSFR1800XS/L ID V Continuous Drain Current FSFR1700XS/L FSFR1600XS/L TC=25C 10.5 TC=100C 6.5 TC=25C 7.0 TC=100C 4.5 TC=25C 6.0 TC=100C 3.9 TC=25C 4.5 TC=100C 2.7 V A A Package Section Torque Recommended Screw Torque 5~7 kgf*cm Notes: 3. Per MOSFET when both MOSFETs are conducting. 4. The maximum value of the recommended operating junction temperature is limited by thermal shutdown. 5. Pulse width is limited by maximum junction temperature. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 4 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Absolute Maximum Ratings TA=25C unless otherwise specified. Symbol JC Parameter Value Junction-to-Case Center Thermal Impedance (Both MOSFETs Conducting) FSFR2100XS/L 10.44 FSFR1800XS/L 10.68 FSFR1700XS/L 10.79 FSFR1600XS/L 10.89 Unit C/W Electrical Characteristics TA=25C unless otherwise specified. Symbol Parameter Test Conditions Min. Typ. Max. Unit MOSFET Section BVDSS RDS(ON) trr Drain-to-Source Breakdown Voltage On-State Resistance Body Diode Reverse (6) Recovery Time ID=200A, TA=25C ID=200A, TA=125C 500 V 540 FSFR2100XS/L VGS=10V, ID=6.0A 0.41 0.51 FSFR1800XS/L VGS=10V, ID=3.0A 0.77 0.95 FSFR1700XS/L VGS=10V, ID=2.0A 1.00 1.25 FSFR1600XS/L VGS=10V, ID=2.25A 1.25 1.55 FSFR2100XS/L VGS=0V, IDiode=10.5A, dIDiode/dt=100A/s 120 FSFR1800XS/L VGS=0V, IDiode=7.0A, dIDiode/dt=100A/s 160 FSFR1700XS/L VGS=0V, IDiode=6.0A, dIDiode/dt=100A/s 160 FSFR1600XS/L VGS=0V, IDiode=4.5A, dIDiode/dt=100A/s 90 ns Supply Section ILK Offset Supply Leakage Current HVCC=VCTR=500V 50 A IQHVCC Quiescent HVCC Supply Current (HVCCUV+) - 0.1V 50 120 A IQLVCC Quiescent LVCC Supply Current (LVCCUV+) - 0.1V 100 200 A IOHVCC Operating HVCC Supply Current (RMS Value) fOSC=100KHz 6 9 mA No Switching 100 200 A IOLVCC Operating LVCC Supply Current (RMS Value) fOSC=100KHz 7 11 mA No Switching 2 4 mA Continued on the following page... (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 5 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Thermal Impedance TA=25C unless otherwise specified. Symbol Parameter Test Conditions Min. Typ. Max. Unit UVLO Section LVCCUV+ LVCC Supply Under-Voltage Positive Going Threshold (LVCC Start) 11.2 12.5 13.8 V LVCCUV- LVCC Supply Under-Voltage Negative Going Threshold (LVCC Stop) 8.9 10.0 11.1 V LVCCUVH LVCC Supply Under-Voltage Hysteresis HVCCUV+ HVCC Supply Under-Voltage Positive Going Threshold (HVCC Start) 8.2 9.2 10.2 V HVCCUV- HVCC Supply Under-Voltage Negative Going Threshold (HVCC Stop) 7.8 8.7 9.6 V HVCCUVH HVCC Supply Under-Voltage Hysteresis 2.50 V 0.5 V Oscillator & Feedback Section VRT V-I Converter Threshold Voltage fOSC Output Oscillation Frequency DC Output Duty Cycle fSS Internal Soft-Start Initial Frequency tSS Internal Soft-Start Time RT=5.2K 1.5 2.0 2.5 V 94 100 106 KHz 48 50 52 % fSS=fOSC+40kHz, RT=5.2K 140 KHz 2 3 4 ms Protection Section VCssH Beginning Voltage to Discharge CSS 0.9 1.0 1.1 V VCssL Beginning Voltage to Charge CSS and Restart 0.16 0.20 0.24 V VOVP LVCC Over-Voltage Protection 21 23 25 V VAOCP AOCP Threshold Voltage -1.0 -0.9 -0.8 V LVCC > 21V (6) tBAO AOCP Blanking Time VOCP OCP Threshold Voltage VCS < VAOCP (6) tBO OCP Blanking Time VCS < VOCP tDA Delay Time (Low Side) Detecting from (6) VAOCP to Switch Off TSD Thermal Shutdown Temperature (6) 50 ns -0.64 -0.58 -0.52 V 1.0 1.5 2.0 s 250 400 ns 135 150 C 120 Dead-Time Control Section DT (7) Dead Time 350 ns Notes: 6. This parameter, although guaranteed, is not tested in production. 7. These parameters, although guaranteed, are tested only in EDS (wafer test) process. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 6 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Electrical Characteristics (Continued) 1.1 1.1 1.05 1.05 Normalized at 25OC Normalized at 25OC These characteristic graphs are normalized at TA=25C. 1 0.95 1 0.95 0.9 0.9 -50 -25 0 25 50 75 -50 100 -25 0 Temp (OC) 50 75 100 Figure 5. Switching Frequency vs. Temperature 1.1 1.1 1.05 1.05 Normalized at 25OC Normalized at 25OC Figure 4. Low-Side MOSFET Duty Cycle vs. Temperature 1 0.95 0.9 1 0.95 0.9 -50 -25 0 25 50 75 100 -50 -25 0 25 50 75 100 Temp (OC) Temp (OC) Figure 6. High-Side VCC (HVCC) Start vs. Temperature Figure 7. High-Side VCC (HVCC) Stop vs. Temperature 1.1 1.1 1.05 1.05 Normalized at 25OC Normalized at 25OC 25 Temp (OC) 1 0.95 1 0.95 0.9 0.9 -50 -25 0 25 50 75 -50 100 Figure 8. Low-Side VCC (LVCC) Start vs. Temperature (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 -25 0 25 50 75 100 Temp (OC) Temp (OC) Figure 9. Low-Side VCC (LVCC) Stop vs. Temperature www.fairchildsemi.com 7 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Typical Performance Characteristics 1.1 1.1 1.05 1.05 Normalized at 25OC Normalized at 25OC These characteristic graphs are normalized at TA=25C. 1 0.95 0.9 1 0.95 0.9 -50 -25 0 25 50 75 100 -50 -25 0 Temp (OC) Figure 10. LVCC OVP Voltage vs. Temperature 50 75 100 Figure 11. RT Voltage vs. Temperature 1.1 1.1 1.05 1.05 Normalized at 25 Normalized at 25 25 Temp (OC) 1 0.95 0.9 1 0.95 0.9 -50 -25 0 25 50 75 100 -50 Temp() -25 0 25 50 75 100 Temp() Figure 12. VCssL vs. Temperature Figure 13. VCssH vs. Temperature 1.1 Normalized at 25OC 1.05 1 0.95 0.9 -50 -25 0 25 50 75 100 Temp (OC) Figure 14. OCP Voltage vs. Temperature (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 8 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Typical Performance Characteristics (Continued) 1. Basic Operation. FSFR-XS series is designed to drive high-side and low-side MOSFETs complementarily with 50% duty cycle. A fixed dead time of 350ns is introduced between consecutive transitions, as shown in Figure 15. Figure 15. MOSFETs Gate Drive Signal 2. Internal Oscillator: FSFR-XS series employs a current-controlled oscillator, as shown in Figure 16. Internally, the voltage of RT pin is regulated at 2V and the charging / discharging current for the oscillator capacitor, CT, is obtained by copying the current flowing out of the RT pin (ICTC) using a current mirror. Therefore, the switching frequency increases as ICTC increases. Figure 17. Resonant Converter Typical Gain Curve LVCC VDL RT Rmax Rmin Rss AR Css CS PG SG Figure 16. Current-Controlled Oscillator Figure 18. Frequency Control Circuit 3. Frequency Setting: Figure 17 shows the typical voltage gain curve of a resonant converter, where the gain is inversely proportional to the switching frequency in the ZVS region. The output voltage can be regulated by modulating the switching frequency. Figure 18 shows the typical circuit configuration for the RT pin, where the opto-coupler transistor is connected to the RT pin to modulate the switching frequency. To prevent excessive inrush current and overshoot of output voltage during startup, increase the voltage gain of the resonant converter progressively. Since the voltage gain of the resonant converter is inversely proportional to the switching frequency, the soft-start is implemented by sweeping down the switching frequency ISS from an initial high frequency (f ) until the output voltage is established. The soft-start circuit is made by connecting R-C series network on the RT pin, as shown in Figure 18. FSFR-XS series also has a 3ms internal soft-start to reduce the current overshoot during the initial cycles, which adds 40kHz to the initial frequency of the external soft-start circuit, as shown in Figure 19. The initial frequency of the soft-start is given as: The minimum switching frequency is determined as: f min = 5.2k x 100(kHz ) Rmin (1) Assuming the saturation voltage of opto-coupler transistor is 0.2V, the maximum switching frequency is determined as: f max = ( 5.2k 4.68k + ) x 100( kHz ) Rmin Rmax (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 f ISS = ( 5.2k 5.2k + ) x 100 + 40 (kHz ) Rmin RSS (3) (2) www.fairchildsemi.com 9 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Functional Description = RSS * CSS (a ) (b ) ( a) (b ) (a ) (b ) L V CC V AR V C ssH V C ssL (4) ICr t stop tS /S (a ) P r o te ction s a r e tr igge r e d, ( b ) F S F R- U S r e sta r ts Figure 21. Self Auto-Restart Operation 5. Protection Circuits: The FSFR-XS series has several self-protective functions, such as Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), OverVoltage Protection (OVP), and Thermal Shutdown (TSD). These protections are auto-restart mode protections, as shown in Figure 22. Figure 19. Frequency Sweeping of Soft-Start 4. Self Auto-Restart: The FSFR-XS series can restart automatically even though any built-in protections are triggered with external supply voltage. As can be seen in Figure 20 and Figure 21, once any protections are triggered, the M1 switch turns on and the V-I converter is disabled. CSS starts to discharge until VCss across CSS drops to VCssL. Then, all protections are reset, M1 turns off, and the V-I converter resumes at the same time. The FSFR-XS starts switching again with soft-start. If the protections occur while VCss is under VCssL and VCssH level, the switching is terminated immediately, VCss continues to increase until reaching VCssH, then CSS is discharged by M1. Once a fault condition is detected, switching is terminated and the MOSFETs remain off. When LVCC falls to the LVCC stop voltage of 10V or AR signal is HIGH, the protection is reset. The FSFR-XS resumes normal operation when LVCC reaches the start voltage of 12.5V. Figure 22. Protection Blocks 5.1 Over-Current Protection (OCP): When the sensing pin voltage drops below -0.58V, OCP is triggered and the MOSFETs remain off. This protection has a shutdown time delay of 1.5s to prevent premature shutdown during startup. Figure 20. Internal Block of AR Pin 5.2 Abnormal Over-Current Protection (AOCP): If the secondary rectifier diodes are shorted, large current with extremely high di/dt can flow through the MOSFET before OCP is triggered. AOCP is triggered without shutdown delay if the sensing pin voltage drops below -0.9V. After protections trigger, FSFR-XS is disabled during the stop-time, tstop, where VCss decreases and reaches to VCssL. The stop-time of FSFR-XS can be estimated as: t STOP = C SS * {(RSS + RMIN ) || 5k} (5) The soft-start time, ts/s can be set as Equation (4). (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 10 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter It is typical to set the initial frequency of soft-start two to three times the resonant frequency (fO) of the resonant network. The soft-start time is three to four times the RC time constant. The RC time constant is: 7. PCB Layout Guidelines: Duty imbalance problems may occur due to the radiated noise from the main transformer, the inequality of the secondary side leakage inductances of main transformer, and so on. This is one of the reasons that the control components in the vicinity of RT pin are enclosed by the primary current flow pattern on PCB layout. The direction of the magnetic field on the components caused by the primary current flow is changed when the high- and low-side MOSFET turn on by turns. The magnetic fields with opposite directions induce a current through, into, or out of the RT pin, which makes the turn-on duration of each MOSFET different. It is strongly recommended to separate the control components in the vicinity of RT pin from the primary current flow pattern on PCB layout. Figure 25 shows an example for the duty-balanced case. 5.4 Thermal Shutdown (TSD): The MOSFETs and the control IC in one package makes it easier for the control IC to detect the abnormal over-temperature of the MOSFETs. If the temperature exceeds approximately 130C, thermal shutdown triggers. 6. Current Sensing Using a Resistor: FSFR-XS series senses drain current as a negative voltage, as shown in Figure 23 and Figure 24. Half-wave sensing allows low power dissipation in the sensing resistor, while full-wave sensing has less switching noise in the sensing signal. Cr Np Ns Ns Control IC VCS Ids CS SG PG Rsense VCS Ids Figure 25. Example for Duty Balancing Figure 23. Half-Wave Sensing Ids VCS Cr Control IC VCS Np CS PG SG Rsense Ns Ns Ids Figure 24. Full-Wave Sensing (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 11 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter 5.3 Over-Voltage Protection (OVP): When the LVCC reaches 23V, OVP is triggered. This protection is used when auxiliary winding of the transformer to supply VCC to the FPSTM is utilized. FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Physical Dimensions Figure 26. 9-Lead Single Inline Package (SIP) 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/. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 12 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter Physical Dimensions Figure 27. 9-Lead Single Inline Package (SIP) L-Forming 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/. (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 13 FSFR-XS Series -- Fairchild Power Switch (FPSTM) for Half-Bridge Resonant Converter (c) 2010 Fairchild Semiconductor Corporation FSFR-XS Series * Rev.1.0.1 www.fairchildsemi.com 14