FAN7602BM

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Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. FAN7602B Green Current-Mode PWM Controller Features Description „ Green Current-Mode PWM Control The FAN7602B is a green current-mode PWM controller. It is specially designed for off-line adapter applications; DVDP, VCR, LCD monitor applications; and auxiliary power supplies. „ Fixed 65kHz Operation „ Internal High-Voltage Start-up Switch „ Burst-Mode Operation „ Line Voltage Feedforward to Limit Maximum Power „ Line Under-Voltage Protection „ Latch Protection & Internal Soft-Start (10ms) Function „ Overload Protection „ Over-Voltage Protection The internal high-voltage start-up switch and the burstmode operation reduce the power loss in standby mode. As a result, it is possible to supply 0.5W load, limiting the input power under 1W when the input line voltage is 265VAC. On no-load condition, input power is under 0.3W. The maximum power can be limited constantly, regardless of the line voltage change, using the power limit function. „ Low Operation Current: 1mA Typical „ 8-pin DIP/SOP The switching frequency is internally fixed at 65kHz. Applications The FAN7602B includes various protections for the system reliability and the internal soft-start prevents the output voltage over-shoot at start-up. „ Adapter „ LCD Monitor Power „ Auxiliary Power Supply Related Application Notes „ AN6014 - Green Current Mode PWM Controller FAN7602 Ordering Information Part Number Operating Temp. Range Pb-Free -25°C to +125°C Yes FAN7602BN FAN7602BM FAN7602BMX © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 Package Packing Method Marking Code 8-DIP Rail FAN7602B Rail FAN7602B Tape & Reel FAN7602B 8-SOP www.fairchildsemi.com FAN7602B — Green Current-Mode PWM Controller March 2007 FAN7602B — Green Current-Mode PWM Controller Typical Application Diagram FAN7602B Figure 1. Typical Flyback Application Internal Block Diagram VSTR 8 6 VCC LUVP LUVP 1 OLP 2V/1.5V OVP Latch OVP Auto Restart Protection SS End Latch Protection Reset Circuit 5V Ref 12V/8V UVLO VCC SS End 10ms Soft Start 19V Driver Circuit PWM Block 5 OUT Plimit Offset 65kHz clock 3 CS/FB Delay Circuit Latch/ Plimit 0.95V/0.88V Latch 2 PWM+ OLP 4V Plimit Offset Plimit Offset Generator Soft Start Power Limit Plimit Offset OLP Soft Start 4 GND Figure 2. Functional Block Diagram of FAN7602B © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 2 VSTR NC VCC Out 8 7 6 5 FAN7602B YWW 1 2 3 4 LUVP Latch/ Plimit CS/FB GND Figure 3. Pin Configuration (Top View) Pin Definitions Pin # Name Description 1 LUVP Line Under-Voltage Protection Pin. This pin is used to protect the set when the input voltage is lower than the rated input voltage range. 2 Latch/Plimit Latch Protection and Power Limit Pin. When the pin voltage exceeds 4V, the latch protection works; the latch protection is reset when the VCC voltage is lower than 5V. For the power limit function, the OCP level decreases as the pin voltage increases. 3 CS/FB Current Sense and Feedback Pin. This pin is used to sense the MOSFET current for the current mode PWM and OCP. The output voltage feedback information and the current sense information are added using an external RC filter. 4 GND Ground Pin. This pin is used for the ground potential of all the pins. For proper operation, the signal ground and the power ground should be separated. 5 OUT Gate Drive Output Pin. This pin is an output pin to drive an external MOSFET. The peak sourcing current is 450mA and the peak sinking current is 600mA. For proper operation, the stray inductance in the gate driving path must be minimized. 6 VCC Supply Voltage Pin. IC operating current and MOSFET driving current are supplied using this pin. 7 NC No Connection. 8 VSTR Start-up Pin. This pin is used to supply IC operating current during IC start-up. After start-up, the internal JFET is turned off to reduce power loss. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 3 FAN7602B — Green Current-Mode PWM Controller Pin Assignments 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 VCC Parameter Supply Voltage Value Unit 20 V IOH, IOL Peak Drive Output Current +450/-600 mA VCS/FB CS/FB Input Voltage -0.3 to 20 V VLUVP LUVP Input Voltage -0.3 to 10 V VLatch Latch/Plimit Input Voltage -0.3 to 10 V VSTR VSTR Input Voltage 600 V TJ Operating Junction Temperature 150 °C TA Operating Temperature Range -25 to 125 °C Storage Temperature Range -55 to 150 °C Power Dissipation 1.2 W VESD_HBM ESD Capability, Human Body Model 2.0 kV VESD_MM ESD Capability, Machine Model 200 V VESD_CDM ESD Capability, Charged Device Model 500 V TSTG PD Thermal Impedance Symbol θJA Parameter Thermal Resistance, Junction-to-Ambient 8-DIP Value Unit 100 °C/W Note: 1. Regarding the test environment and PCB type, please refer to JESD51-2 and JESD51-10. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 4 FAN7602B — Green Current-Mode PWM Controller Absolute Maximum Ratings VCC = 14V, TA = -25°C~125°C, unless otherwise specified Symbol Parameter Condition Min. Typ. Max. Unit VSTR = 30V, TA = 25°C 0.7 1.0 1.4 mA START UP SECTION ISTR VSTR Start-up Current UNDER VOLTAGE LOCK OUT SECTION Vth(start) Start Threshold Voltage VCC increasing 11 12 13 V Vth(stop) Stop Threshold Voltage VCC decreasing 7 8 9 V HY(uvlo) UVLO Hysteresis 3.6 4.0 4.4 V SUPPLY CURRENT SECTION ISTR Start-up Supply Current TA = 25°C 250 320 μA ICC Operating Supply Current Output no switching 1.0 1.5 mA 5 10 15 ms VCS/FB = 0.2V, TA = 25°C 59 65 73 kHz TA = 25°C 0.9 1.0 1.1 V 100 150 ns 75 80 % 0 % SOFT-START SECTION tSS Soft-Start Time(1) PWM SECTION fOSC VCS/FB1 Operating Frequency CS/FB Threshold Voltage tD Propagation Delay to DMAX Maximum Duty Cycle DMIN Minimum Duty Cycle Output(1) 70 BURST MODE SECTION VCS/FB2 Burst On Threshold Voltage TA = 25°C 0.84 0.95 1.06 V VCS/FB3 Burst Off Threshold Voltage TA = 25°C 0.77 0.88 0.99 V VLatch/Plimit = 2V, TA = 25°C 0.12 0.16 0.20 11.5 12.0 14.0 V POWER LIMIT SECTION KPlimit Offset Gain OUTPUT SECTION VOH Output Voltage High TA = 25°C, Isource = 100mA VOL Output Voltage Low TA = 25°C, Isink = 100mA 1.0 2.5 V tR Rising Time(1) TA = 25°C, CL = 1nF 45 150 ns Falling Time(1) TA = 25°C, CL= 1nF 35 150 ns 3.6 4.0 4.4 V 20 22 24 ms 30 37 44 ms 0 0.1 V tF PROTECTION SECTION VLatch tOLP tOLP_ST VOLP Latch Voltage Overload Protection Time (1) Overload Protection Time at Startup Overload Protection Level VLUVPoff Line Under-Voltage Protection On to Off TA = 25°C 1.9 2.0 2.1 V VLUVPon Line Under-Voltage Protection Off to On TA = 25°C 1.4 1.5 1.6 V Over-Voltage Protection TA = 25°C 18 19 20 V VOVP Note: 1. These parameters, although guaranteed by design, are not tested in production. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 5 FAN7602B — Green Current-Mode PWM Controller Electrical Characteristics 8.8 12.4 8.4 VTL[V] VTH[V] 12.8 12.0 8.0 11.6 7.6 11.2 7.2 -25 0 25 50 75 100 -25 125 0 25 50 75 100 125 Temperature [°C] Temperature [°C] Figure 4. Start Threshold Voltage vs. Temp. Figure 5. Stop Threshold Voltage vs. Temp. 4.4 350 4.2 300 4.1 Ist [μA] UVLO Hysteresis [V] 4.3 4.0 250 3.9 3.8 200 3.7 3.6 -25 0 25 50 75 100 150 -25 125 0 Temperature [°C] 25 50 75 100 125 Temperature [°C] Figure 6. UVLO Hysteresis vs. Temp. Figure 7. Start-up Supply Current vs. Temp. 1.5 1.3 1.4 1.2 Istr [mA] Iop [mA] 1.3 1.2 1.1 1.1 1.0 1.0 0.9 0.9 0.8 -25 0 25 50 75 100 0.8 -25 125 Temperature [°C] 25 50 75 100 125 Temperature [°C] Figure 9. VSTR Star-up Current vs. Temp. Figure 8. Operating Supply Current vs. Temp. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 0 www.fairchildsemi.com 6 FAN7602B — Green Current-Mode PWM Controller Typical Performance Characteristics 70 1.10 CSFB2 CSFB3 68 1.00 Fosc [kHz] CS/FB Threshold [V] 1.05 0.95 0.90 0.85 0.80 66 64 62 0.75 0.70 -25 0 25 50 75 100 60 -25 125 0 Temperature [°C] 75 100 125 Figure 11. Operating Frequency vs. Temp. 0.20 80 0.18 78 Dmax [%] Kplimit 50 Temperature [°C] Figure 10. Burst On/Off Voltage vs. Temp. 0.16 0.14 0.12 76 74 72 0.10 -25 0 25 50 75 100 70 -25 125 0 Temperature [°C] 25 50 75 100 125 Temperature [°C] Figure 12. Offset Gain vs. Temp. Figure 13. Maximum Duty Cycle vs. Temp. 4.4 20.0 19.6 4.2 VLATCH [V] VOVP [V] 25 19.2 18.8 4.0 3.8 18.4 18.0 -25 0 25 50 75 100 3.6 -25 125 Temperature [°C] 25 50 75 100 125 Temperature [°C] Figure 14. OVP Voltage vs. Temp. Figure 15. Latch Voltage vs. Temp. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 0 www.fairchildsemi.com 7 FAN7602B — Green Current-Mode PWM Controller Typical Performance Characteristics (Continued) 2.10 1.70 1.65 VLUVPon [V] VLUVPoff [V] 2.05 2.00 1.60 1.55 1.50 1.95 1.45 1.90 -25 0 25 50 75 100 1.40 -25 125 Temperature [°C] 25 50 75 100 125 Temperature [°C] Figure 16. LUVP On-to-Off Voltage vs. Temp. CSFB1 Threshold voltage [V] 0 Figure 17. LUVP Off-to-On Voltage vs. Temp. 1.08 1.04 1.00 0.96 0.92 -25 0 25 50 75 100 125 Temperature [°C] Figure 18. CS/FB Threshold Voltage vs. Temp. © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 8 FAN7602B — Green Current-Mode PWM Controller Typical Performance Characteristics (Continued) 1. Start-up Circuit and Soft Start Block charging CF to adjust the offset voltage. If IFB is zero, CF is discharged through RF and RS to lower offset voltage. The FAN7602B contains a start-up switch to reduce the power loss of the external start-up circuit of the conventional PWM converters. The internal start-up circuit charges the VCC capacitor with 0.9mA current source if the AC line is connected. The start-up switch is turned off 15ms after IC starts up, as shown in Figure 19. The softstart function starts when the VCC voltage reaches the start threshold voltage of 12V and ends when the internal soft-start voltage reaches 1V. The internal start-up circuit starts charging the VCC capacitor again if the Vcc voltage is lowered to the minimum operating voltage, 8V. The UVLO block shuts down the output drive circuit and some blocks to reduce the IC operating current and the internal soft-start voltage drops to zero. If the VCC voltage reaches the start threshold voltage, the IC starts switching again and the soft-start block works as well. Figure 21 shows typical voltage waveforms of the CS/FB pin. The current-sense waveform is added to the offset voltage, as shown in Figure 21. The CS/FB pin voltage is compared with PWM+ that is 1V - Plimit offset. If the CS/ FB voltage meets PWM+, the output drive is shut off. If the feedback offset voltage is low, the switch on time is increased. If the feedback offset voltage is high, the switch on time is decreased. In this way, the duty cycle is controlled according to the output load condition. In general, the maximum output power increases as the input voltage increases because the current slope during switch on-time increases. To limit the output power of the converter constantly, a power-limit function is included. Sensing the converter input voltage through the Latch/Plimit pin, the Plimit offset voltage is subtracted from 1V. As shown in Figure 21, the Plimit offset voltage is subtracted from 1V and the switch on-time decreases as the Plimit offset voltage increases. If the converter input voltage increases, the switch on-time decreases, keeping the output power constant. The offset voltage is proportional to the Latch/ Plimit pin voltage and the gain is 0.16; if the Latch/Plimit voltage is 1V, the offset voltage is 0.16V. During the soft-start, the pulse-width modulated (PWM) comparator compares the CS/FB pin voltage with the soft-start voltage. The soft-start voltage starts from 0.5V and the soft-start ends when it reaches 1V and the softstart time is 10ms. The start-up switch is turned off when the soft-start voltage reaches 1.5V. VCC 12V 8V Vcc Start-up Current 1.5V 1V 0.5V PWM Comparator PWM+ Soft Start Voltage Soft Start Time (10ms) Soft Start Plimit Offset RFB Power Limit 3 CS/FB IFB RF Isw CF t RS 5ms Figure 19. Start-up Current and VCC Voltage Figure 20. Current-Sense and Feedback Circuits 2. Oscillator Block 1V Power Limit Offset PWM+ The oscillator frequency is set internally. The switching frequency is 65kHz. CS/FB FB Offset 3. Current Sense and Feedback Block GND The FAN7602B performs the current sensing for the current-mode PWM and the output voltage feedback with only one pin, pin3. To achieve the two functions with one pin, an internal leading edge blanking (LEB) circuit to filter the current-sense noise is not included because the external RC filter is necessary to add the output voltage feedback information and the current-sense information. Figure 20 shows the current-sense and feedback circuits. RS is the current-sense resistor to sense the switch current. The current-sense information is filtered by an RC filter composed of RF and CF. According to the output voltage feedback information, IFB charges or stops 1V Power Limit Offset PWM+ CS/FB GND FB Offset On Time (b) High-Power Limit Offset Case Figure 21. CS/FB Pin Voltage Waveforms © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 On Time (a) Low-Power Limit Offset Case www.fairchildsemi.com 9 FAN7602B — Green Current-Mode PWM Controller Applications Information voltage feedback loop is saturated, and the OLP initiates if the LUVP condition persists more than 22ms. The FAN7602B contains the burst-mode block to reduce the power loss at a light load and no load. A hysteresis comparator senses the offset voltage of the Burst+ for the burst mode, as shown in Figure 22. The Burst+ is the sum of the CS/FB voltage and Plimit offset voltage. The FAN7602B enters burst mode when the offset voltage of the Burst+ is higher than 0.95V and exits the burst mode when the offset voltage is lower than 0.88V. The offset voltage is sensed during the switch off time. Vin 1 + − B u rs t+ 3 LUVP 2V/1.5V Figure 24. Line UVP Circuit 5.3 Latch Protection The latch protection is provided to protect the system against abnormal conditions using the Latch/Plimit pin. The Latch/Plimit pin can be used for the output overvoltage protection and/or other protections. If the Latch/ Plimit pin voltage is made higher than 4V by an external circuit, the IC is shut down. The latch protection is reset when the VCC voltage is lower than 5V. O ffs e t D e la y C irc u it − + C S /F B 0 .9 5 V /0 .8 8 V Figure 22. Burst-Mode Block 5. Protection Block 5.4 Over-Voltage Protection (OVP) If the VCC voltage reaches 19V, the IC shuts down and the OVP protection is reset when the VCC voltage is lower than 5V. The FAN7602B contains several protection functions to improve system reliability. 5.1 Overload Protection (OLP) The FAN7602B contains the overload protection function. If the output load is higher than the rated output current, the output voltage drops and the feedback error amplifier is saturated. The offset of the CS/FB voltage representing the feedback information is almost zero. As shown in Figure 23, the CS/FB voltage is compared with 50mV reference when the internal clock signal is high and, if the voltage is lower than 50mV, the OLP timer starts counting. If the OLP condition persists for 22ms, the timer generates the OLP signal. This protection is reset by the UVLO. The OLP block is enabled after the soft-start finishes. 6. Output Drive Block The FAN7602B contains a single totem-pole output stage to drive a power MOSFET. The drive output is capable of up to 450mA sourcing current and 600mA sinking current with typical rise and fall time of 45ns and 35ns, respectively, with a 1nF load. Clock OLP 3 CS/FB 22ms Timer Soft-Start 50mV Figure 23. Overload Protection Circuit 5.2 Line Under-Voltage Protection If the input voltage of the converter is lower than the minimum operating voltage, the converter input current increases too much, causing component failure. Therefore, if the input voltage is low, the converter should be protected. In the FAN7602B, the LUVP circuit senses the input voltage using the LUVP pin and, if this voltage is lower than 2V, the LUVP signal is generated. The comparator has 0.5V hysteresis. If the LUVP signal is generated, the output drive block is shut down, the output © 2007 Fairchild Semiconductor Corporation FAN7602B Rev. 1.0.0 www.fairchildsemi.com 10 FAN7602B — Green Current-Mode PWM Controller 4. Burst-Mode Block Application Output Power Input Voltage Output Voltage Adapter 48W Universal input (85~265VAC) 12V Features „ Low stand-by power (