FSDM0465RB

FSCM0465R Green Mode Fairchild Power Switch (FPS™) June 2006 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Features Internal Avalanche Rugged SenseFET Low Start-up Current (max. 40µA) Low Power Consumption; under 1W at 240VAC and 0.4W Load Precise Fixed Operating Frequency (66kHz) Frequency Modulation for Low EMI Pulse-by-Pulse Current Limiting (Adjustable) Over-Voltage Protection (OVP) Overload Protection (OLP) Thermal Shutdown Function (TSD) Auto-Restart Mode Under-Voltage Lock Out (UVLO) with Hysteresis Built-in Soft-Start (15ms) Description The FSCM0465R is an integrated Pulse-Width Modulator (PWM) and SenseFET specifically designed for high-performance offline Switch Mode Power Supplies (SMPS) with minimal external components. This device is an integrated high-voltage powerswitching regulator that combines an avalanche rugged SenseFET with a current mode PWM control block. The PWM controller includes an integrated fixed-frequency oscillator, under-voltage lockout, leading edge blanking (LEB), optimized gate driver, internal soft-start, temperature-compensated precise current sources for a loop compensation, and self-protection circuitry. Compared with a discrete MOSFET and PWM controller solution, it can reduce total cost, component count, size, and weight while simultaneously increasing efficiency, productivity, and system reliability. This device is a basic platform well suited for cost-effective designs of flyback converters. Applications SMPS for VCR, SVR, STB, DVD, and DVCD Adaptor SMPS for LCD Monitor Related Application Notes AN-4137: Design Guidelines for Off-line Flyback Converters Using Fairchild Power Switch (FPS) AN-4140: Transformer Design Consideration for Off-line Flyback Converters using Fairchild Power Switch AN-4141: Troubleshooting and Design Tips for Fairchild Power Switch Flyback Applications AN-4148: Audible Noise Reduction Techniques for FPS Applications Ordering Information Product Number FSCM0465RJ FSCM0465RJX FSCM0465RIWDTU(1) FSCM0465RGWDTU (1) Package D2-PAK-6L D2-PAK-6L I2-PAK-6L TO-220-6L Pb-Free Marking Code Yes Yes Yes Yes CM0465R BVDSS RDS(ON) Max. Packing Method Tube Tape & Reel Tube Tube 650V 2.6 Ω Note: 1. WDTU: Forming Type FPSTM is a trademark of Fairchild Semiconductor Corporation. © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 1 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Typical Circuit DC OUT AC IN Drain PWM Ilimit Vfb Vcc GND FSCM0465R Rev. 00 Figure 1. Typical Flyback Application Output Power Table Product FSCM0465RJ FSCM0565RJ FSCM0765RJ FSCM0465RI FSCM0465RG FSCM0565RG FSCM0765RG 230VAC ±15%(3) Adapter 40W 50W 65W 60W 60W 70W 85W (1) 85–265VAC (2) Open Frame 55W 65W 70W 70W 70W 85W 95W Adapter 30W 40W 50W 40W 40W 60W 70W (1) Open Frame(2) 40W 50W 60W 50W 50W 70W 85W Notes: 1. Typical continuous power in a non-ventilated enclosed adapter measured at 50°C ambient 2. Maximum practical continuous power in an open-frame design at 50°C ambient 3. 230 VAC or 100/115 VAC with doubler © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 2 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Internal Block Diagram N.C. 5 VCC 3 VCC Good Vref Internal Bias Drain 1 0.3/0.5V + 8V/12V Freq. Modulation VCC IDELAY VCC OSC IFB PWM 2.5R S Q Q FB 4 6 I_limit 0.3K R R Soft start Gate Driver LEB VSD VCC S Q Q 2 GND Vovp TSD VCC UV Reset Vcc Good R FSCM0465R Rev. 00 Figure 2. Functional Block Diagram of FSCM0465R © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 3 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Pin Configuration FSCM0465RJ D2-PAK-6L 6 : I_limit 5 : N.C. 4 : FB 3 : VCC 2 : GND 1 : Drain FSCM0465RI I2-PAK-6L 6 : I_limit 5 : N.C. 4 : FB 3 : VCC 2 : GND 1 : Drain FSCM0465RJ FSCM0465RG TO-220-6L FSCM0465RI FSCM0465RG 6. I_limit 5. N.C. 4. FB 3. VCC 2. GND 1. Drain Figure 3. Pin Configuration (Top View) Pin Definitions Pin Number 1 2 3 Pin Name Drain GND VCC Pin Function Description SenseFET Drain. This pin is the high-voltage power SenseFET drain. It is designed to drive the transformer directly. Ground. This pin is the control ground and the SenseFET source. Power Supply. This pin is the positive supply voltage input. During startup, the power is supplied through the startup resistor from DC link. When VCC reaches 12V, the power is supplied from the auxiliary transformer winding. Feedback. This pin is internally connected to the inverting input of the PWM comparator. The collector of an opto-coupler is typically tied to this pin. For stable operation, a capacitor should be placed between this pin and GND. If the voltage of this pin reaches 6.0V, the overload protection is activated, resulting in shutdown of the FPS. This pin is not connected. Current Limit. This pin is for the pulse-by-pulse current limit level programming. By using a resistor to GND on this pin, the current limit level can be changed. If this pin is left floating, the typical current limit is 2.0A. 4 Feedback (FB) 5 6 N.C. I_limit © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 4 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Absolute Maximum Ratings The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. TA = 25°C unless otherwise specified. Symbol BVDSS VDGR VGS IDM Parameter Drain-Source Breakdown Voltage Drain-Gate Voltage (RGS=1MΩ) Gate-Source (GND) Voltage Drain Current Pulsed(2) Continuous Drain Current (TO-220-6L, I2-PAK-6L) TC = 25°C TC = 100°C TC = 25°C TC = 100°C (1) Value 650 650 ±30 16 4.0 2.5 2.3 1.4 20 -0.3 to VCC 140 -1.1 75 -1.5 80 -0.64 Internally limited -25 to +85 -55 to +150 2.0 (GND-Vfb = 1.5kV) (VCC-Vfb = 1.0kV) 300 (GND-Vfb = 250V) (VCC-Vfb = 100V) Unit V V V ADC ADC ADC ADC ADC V V W W/°C W W/°C W W/°C °C °C °C kV ID Continuous Drain Current (D2-PAK-6L) Supply Voltage Feedback Voltage Range Total Power Dissipation (TO-220-6L) Total Power Dissipation (I2-PAK-6L) Total Power Dissipation (D2-PAK-6L) Operating Junction Temperature Operating Ambient Temperature Storage Temperature ESD Capability, HBM Model (All pins except Vfb) ESD Capability, Machine Model (All pins except Vfb) VCC VFB PD Derating PD Derating PD Derating TJ TA TSTG V Notes: 1. Tj = 25°C to 150°C 2. Repetitive rating: Pulse-width limited by maximum junction temperature 3. TC: Case back surface temperature with infinite heat sink © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 5 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Electrical Characteristics TA = 25°C unless otherwise specified. Symbol SenseFET SECTION IDSS RDS(ON) COSS td(on) tr td(off) tf fOSC ΔfMOD tMOD fSTABLE ΔfOSC DMAX DMIN VSTART VSTOP IFB tS/S VBURH VBURL ILIMIT VOVP TSD IDELAY VSD Istart IOP(MIN) IOP(MAX) Parameter Zero Gate Voltage Current Static Drain Source on Resistance(1) Output Capacitance Turn-on Delay Time Rise Time Turn-off Delay Time Fall Time Switching Frequency Switching Frequency Modulation Range Switching Frequency Modulation Cycle Switching Frequency Stability Switching Frequency Maximum Duty Cycle Minimum Duty Cycle UVLO Threshold Voltage Feedback Source Current Internal Soft-Start Time Variation(2) Condition VDS = Max, Rating VGS = 0V VGS = 10V, ID = 2.3A VGS = 0V, VDS = 25V, f = 1MHz Min. Typ. Max. Unit 2.2 60 23 20 65 27 66 ±3 4 1 ±5 80 12 8 0.9 15 0.5 0.3 2.5 19 145 5.3 6 20 2.5 250 2.6 72 3 ±10 85 0 13 9 1.1 20 0.6 0.36 2.8 20 160 7 6.5 40 5 kHz kHz ms % % % % V V mA ms V V A V °C µA V µA mA ns µA Ω pF VDD = 325V, ID = 3.2A(4) CONTROL SECTION VCC = 14V, VFB = 5V 60 10V ≤ VCC ≤ 17V −25°C ≤ TA ≤ +85°C 0 75 VFB = GND VFB = GND 11 7 0.7 10 VCC = 14V VCC = 14V VCC = 14V, VFB = 5V 0.4 0.24 2.2 18 130 VFB = 4V VFB ≥ 5.5V 3.5 5.5 VCC = 10V, VFB = 0V VCC = 20V, VFB = 0V - BURST MODE SECTION Burst Mode Voltages PROTECTION SECTION Peak Current Limit(3) Over-Voltage Protection Thermal Shutdown Temperature(2) Shutdown Delay Current Shutdown Feedback Voltage Startup Current Operating Supply Current TOTAL DEVICE SECTION Notes: 1. Pulse Test: Pulse width ≤ 300µS, duty ≤ 2% 2. These parameters, although guaranteed at the design, are not tested in mass production. 3. These parameters indicate the inductor current. Where packages are I2PAK or D2PAK, this should be decreased to 2.0A by external resistor. 4. MOSFET switching time is essentially independent of operating temperature. © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 6 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Comparison Between FSDM0465RB and FSCM0465R Function Frequency Modulation Pulse-by-pulse Current Limit Internal Startup Circuit N/A Internally fixed (2.0A max.) Available FSDM0465RB FSCM0465R Available - Frequency modulation range (ΔfMOD) = ±3kHz - Frequency modulation cycle (tMOD) = 4ms Programmable using external resistor (2.8A max.) N/A (Requires a startup resistor) Startup current: 40µA (max.) TO-220-6L I2-PAK-6L D2-PAK-6L Packages TO-220F-6L © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 7 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Typical Performance Characteristics These characteristic graphs are normalized at TA= 25°C. 1.60 1.40 1.20 1.00 0.80 0.60 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Stop Threshold Voltage (Normalized to 25°C) 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Start up Current (Normalized to 25°C) Junction Temperature [°C] Figure 4. Startup Current vs. Temp. Figure 5. Stop Threshold voltage vs. Temp. 1.20 Maximum Duty Cycle (Normalized to 25°C) 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Start Threshold Voltage (Normalized to 25°C) 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Junction Temperature [°C] Figure 6. Maximum Duty Cycle vs. Temp. Figure 7. Start Threshold Voltage vs. Temp. 1.20 Initial Frequency (Normalized to 25°C) FB Source Current (Normalized to 25°C) 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Junction Temperature [°C] Figure 8. Initial Frequency vs. Temp. Figure 9. Feedback Source Current vs. Temp. © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 8 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Typical Performance Characteristics (Continued) These characteristic graphs are normalized at TA= 25°C. 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Burst Mode Enable Voltage (Normalized to 25°C) Shutdown FB Voltage (Normalized to 25°C) 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Junction Temperature [°C] Figure 10. Shutdown Feedback voltage vs. Temp. Figure 11. Burst Mode Enable Voltage vs. Temp. 1.20 Shutdown Delay Current (Normalized to 25°C) Maximum Drain Current (Normalized to 25°C) 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Junction Temperature [°C] Figure 12. Maximum Drain Current vs. Temp. Figure 13. Shutdown Delay Current vs. Temp. 1.20 Burst Mode Disable Voltage (Normalized to 25°C) 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Operating Supply Current (Normalized to 25°C) 1.20 1.12 1.04 0.96 0.88 0.80 -50 -25 0 25 50 75 100 125 Junction Temperature [°C] Junction Temperature [°C] Figure 14. Burst Mode Disable Voltage vs. Temp. Figure 15. Operating Supply Current vs. Temp. © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 9 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Functional Description 1. Startup: Figure 16 shows the typical startup circuit and transformer auxiliary winding for the FSCM0465R application. Before the FSCM0465R begins switching, it consumes only startup current (typically 20µA) and the current supplied from the DC link supply current consumed by the FPS (ICC) and charges the external capacitor (Ca) connected to the VCC pin. When VCC reaches start voltage of 12V (VSTART), the FSCM0465R begins switching and the current consumed by the FSCM0465R increases to 2.5mA. Then the FSCM0465R continues its normal switching operation and the power required for this device is supplied from the transformer auxiliary winding, unless VCC drops below the stop voltage of 8V (VSTOP). To guarantee the stable operation of the control IC, VCC has under-voltage lockout (UVLO) with 4V hysteresis. Figure 17 shows the relationship between the current consumed by the FPS (ICC) and the supply voltage (VCC). The minimum current supplied through the startup resistor is given by: Isup min = ( 2 ⋅ Vline min − Vstar t ⋅ ) 1 Rstr (1) where Vlinemin is the minimum input voltage, Vstart is the start voltage (12V) and Rstr is the startup resistor. The startup resistor should be chosen so that Isupmin is larger than the maximum startup current (40µA). If not, VCC can not be charged to the start voltage and FPS fails to start. CDC 2. Feedback Control: The FSCM0465R employs current mode control, as shown in Figure 18. An optocoupler (such as the H11A817A) and a shunt regulator (such as the KA431) are typically used to implement the feedback network. Comparing the feedback voltage with the voltage across the Rsense resistor makes it possible to control the switching duty cycle. When the reference pin voltage of the KA431 exceeds the internal reference voltage of 2.5V, the H11A817A LED current increases, pulling down the feedback voltage and reducing the duty cycle. This event typically happens when the input voltage is increased or the output load is decreased. 2.1 Pulse-by-pulse Current Limit: Because current mode control is employed, the peak current through the SenseFET is determined by the inverting input of the PWM comparator (Vfb*) as shown in Figure 18. When the current through the opto-transistor is zero and the current limit pin (#5) is left floating, the feedback current source (IFB) of 0.9mA flows only through the internal resistor (R+2.5R=2.8k). In this case, the cathode voltage of diode D2 and the peak drain current have maximum values of 2.5V and 2.5A, respectively. The pulse-bypulse current limit can be adjusted using a resistor to GND on the current limit pin (#5). The current limit level using an external resistor (RLIM) is given by: AC line (Vlinemin - Vlinemax) ISUP Rstr Da VCC FSCM0465R ICC Ca FSCM0465R Rev. 00 Figure 16. Startup Circuit ICC ILIM = RLIM ⋅ 2.5 A 2.8K Ω + RLIM (2) Vcc Idelay Vref IFB 0.9mA OSC 3mA Vo H11A817A Vfb 4 CB SenseFET D1 0.3k D2 2.5R + Vfb* Gate driver Power Down 25μA FSCM0465R Rev. 00 Power Up KA431 R 6 RLI M - VCC Vstop=8V Vstart=12V Vz FSCM0465R Rev. 00 VSD OLP Rsense Figure 17. Relation Between Operating Supply Current and VCC Voltage Figure 18. Pulse Width Modulation (PWM) Circuit © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 10 FSCM0465R Green Mode Fairchild Power Switch (FPS™) 2.2 Constant Power Limit Circuit: Due to the circuit delay of FPS, the pulse-by-pulse limit current increases a little bit when the input voltage increases. This means unwanted excessive power is delivered to the secondary side. To compensate, the auxiliary power compensation network in Figure 19 can be used. RLIM can adjust pulseby-pulse current by absorbing internal current source (IFB: typical value is 0.9mA), depending on the ratio between resistors. With the suggested compensation circuit, additional current from IFB is absorbed more proportionally to the input voltage (VDC) and achieves constant power in wide input range. Choose RLIM for proper current to the application, then check the pulseby-pulse current difference between minimum and maximum input voltage. To eliminate the difference (to gain constant power), Ry can be calculated by: 2.3 Leading Edge Blanking (LEB): At the instant the internal SenseFET is turned on, a high-current spike through the SenseFET usually occurs, caused by primary-side capacitance and secondary-side rectifier reverse recovery. Excessive voltage across the Rsense resistor can lead to incorrect feedback operation in the current mode PWM control. To counter this effect, the FSCM0465R employs a leading edge blanking (LEB) circuit. This circuit inhibits the PWM comparator for a short time after the SenseFET is turned on. 3. Protection Circuit: The FSCM0465R has several self-protective functions, such as overload protection (OLP), over-voltage protection (OVP) and thermal shutdown (TSD). Because these protection circuits are fully integrated into the IC without external components, the reliability is improved without increasing cost. Once the fault condition occurs, switching is terminated and the SenseFET remains off. This causes VCC to fall. When VCC reaches the UVLO stop voltage of 8V, the current consumed by the FSCM0465R decreases to the startup current (typically 20µA) and the current supplied from the DC link charges the external capacitor (Ca) connected to the VCC pin. When VCC reaches the start voltage of 12V, the FSCM0465R resumes normal operation. In this manner, the auto-restart can alternately enable and disable the switching of the power SenseFET until the fault condition is eliminated (see Figure 20). Fault occurs Ilim_spec × Vdc × Ry ≅ Na Np Ifb × ΔIlim_comp (3) where, Ilim_spec is the limit current stated on the specification; Na and Np are the number of turns for VCC and primary side, respectively; Ifb is the internal current source at feedback pin with a typical value of 0.9mA; and ΔIlim_comp is the current difference which must be eliminated. In case of capacitor in the circuit 1µF, 100V is good choice for all applications. Vds Power On Fault removed VDC Np Vcc L 12V 8V Vfb Drain Na Vcc FSCM0465R Rev. 00 t Normal Operation Fault Situation Normal Operation I_lim RLIM GND compensation network - Figure 20. Auto Restart Operation 3.1 Overload Protection (OLP): Overload is defined as the load current exceeding a preset level due to an unexpected event. In this situation, the protection circuit should be activated to protect the SMPS. However, even when the SMPS is in the normal operation, the overload protection circuit can be activated during the load RY FSCM0465R Rev. 00 CY + Vy = VDC × Na Np Figure 19. Constant power limit circuit © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 11 FSCM0465R Green Mode Fairchild Power Switch (FPS™) transition. To avoid this undesired operation, the overload protection circuit is designed to be activated after a specified time to determine whether it is a transient situation or an overload situation. Because of the pulse-by-pulse current limit capability, the maximum peak current through the SenseFET is limited and the maximum input power is restricted with a given input voltage. If the output consumes beyond this maximum power, the output voltage (VO) decreases below the set voltage. This reduces the current through the optocoupler LED, which also reduces the opto-coupler transistor current, increasing the feedback voltage (Vfb). If Vfb exceeds 2.5V, D1 is blocked and the 5.3µA current source (Idelay) starts to charge CB slowly up to VCC. In this condition, Vfb continues increasing until it reaches 6V, when the switching operation is terminated as shown in Figure 21. The delay time for shutdown is the time required to charge CB from 2.5V to 6.0V with 5.3µA (Idelay). A 10 ~ 50ms delay time is typical for most applications. VFB FSCM0465R Rev. 00 3.3 Thermal Shutdown (TSD): The SenseFET and the control IC are built in one package. This makes it easy for the control IC to detect the heat generation from the SenseFET. When the temperature exceeds approximately 145°C, the thermal protection is triggered, resulting in shutdown of the FPS. 4. Frequency Modulation: EMI reduction can be accomplished by modulating the switching frequency of a switched power supply. Frequency modulation can reduce EMI by spreading the energy over a wider frequency range than the bandwidth measured by the EMI test equipment. The amount of EMI reduction is directly related to the depth of the reference frequency. As can be seen in Figure 22, the frequency changes from 63KHz to 69KHz in 4ms. Drain Current Overload Protection 6.0V Ts Ts 2.5V T12= CB*(6.0-2.5)/Idelay T1 T2 Ts fs t 69kHz 66kHz 63kHz Figure 21. Overload Protection 3.2 Over-Voltage Protection (OVP): If the secondaryside feedback circuit were to malfunction or a solder defect causes an opening in the feedback path, the current through the opto-coupler transistor becomes almost zero. In this case, Vfb climbs up in a similar manner to the overload situation, forcing the preset maximum current to be supplied to the SMPS until the overload protection is activated. Because more energy than required is provided to the output, the output voltage may exceed the rated voltage before the overload protection is activated, resulting in the breakdown of the devices in the secondary side. To prevent this situation, an over- voltage protection (OVP) circuit is employed. In general, VCC is proportional to the output voltage and the FSCM0465R uses VCC instead of directly monitoring the output voltage. If VCC exceeds 19V, an OVP circuit is activated, resulting in the termination of the switching operation. To avoid undesired activation of OVP during normal operation, VCC should be designed to be below 19V. FSCM0465R Rev. 00 4ms t Figure 22. Frequency Modulation 5. Soft-Start: The FSCM0465R has an internal soft-start circuit that increases PWM comparator inverting input voltage, together with the SenseFET current, slowly after it starts up. The typical soft-start time is15ms. The pulse width to the power switching device 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. Preventing transformer saturation and reducing stress on the secondary diode during startup is also helpful. © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 12 FSCM0465R Green Mode Fairchild Power Switch (FPS™) 6. Burst Operation: To minimize power dissipation in standby mode, the FSCM0465R enters into burst-mode operation at light load condition. As the load decreases, the feedback voltage decreases. As shown in Figure 23, the device automatically enters burst mode when the feedback voltage drops below VBURL (300mV). At this point, switching stops and the output voltages start to drop at a rate dependent on standby current load. This causes the feedback voltage to rise. Once it passes VBURH (500mV), switching resumes. The feedback voltage then falls and the process repeats. Burst mode operation alternately enables and disables switching of the power SenseFET, thereby reducing switching loss in standby mode. Vo Voset VFB 0.5V 0.3V Ids Vds time Switching disabled FSCM0465R Rev. 00 T1 T2 T3 Switching disabled T4 Figure 23. Waveforms of Burst Operation © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FSCM0465R Rev. 1.0.1 13 FSCM0465R Green Mode Fairchild Power Switch (FPS™) Typical Application Circuit Application LCD Monitor Output Power 40W Input Voltage Universal Input (85-265Vac) Output Voltage (Max. Current) 5V (2.0A) 12V (2.5A) Features High efficiency (>81% at 85Vac input) Low standby mode power consumption (