www.fairchildsemi.com FAN7548 Dual LCD Back Light Inverter Drive IC Features Description • • • • • • • • • • • • • The FAN7548 provides the necessary circuit blocks to implement a highly efficient CCFL backlight power supply in a small footpirnt 20 SSOP package. The device features two control stages for operating independent resonant tanks for multi-lamp designs. External parts count is minimized and system cost is reduced by integration such features as a feedback controlled PWM driver stage, the soft start, the open lamp regulation, the open lamp protection, the UVLO, and the self-synchronization circuitry between the buck and Royer stages. It includes an internal shunt regulator, allowing it to operate with input voltage from 9 to 30V. It supports analog and burst dimming modes of operation. It providees the open lamp regulation, and the open lamp protection. Backlight Lamp Ballast and Soft Dimming Reduce the Number of Components Wide Range Operating Voltage 9-30V Precision Voltage Reference Trimmed to 3.4% Low Standby Current (Typ. 150uA) Soft Start Function Dual PWM Control Analog & Burst Dimming Function P-Channel MOSFET Drive Open Lamp Regulation(OLR) Open Lamp Protection(OLP) Buck+Royer Topology 20 SSOP 20-SSOP 1 Rev. 1.0.0 ©2003 Fairchild Semiconductor Corporation FAN7548 Internal Block Diagram ENA 3Vref V3 Internal Bias Vz Vcc Va ADIM Vb BDIM + UVLO 5.2V GND Output Drive2 Output Drive1 OUT1 OUT2 13.5V 13.5V Vz Vz 2uA 2uA OLP2 Q S + COMP6 - COMP1 3.7V - Q S 3.7V + OLP1 R R 2.5V 2.5V SBurst1 Buffer Error Amp.2 Buffer - - + + + - Css Va + VFB1 SBurst2 COMP9 COMP4 Error Amp.1 + SOLR1 + + + SOLR2 VFB2 Css Va 2.5V 2.5V Css COMP1 COMP2 Ramp Ramp OSC1 OSC2 COMP7 - Sync. Sync. COMP2 - + + 1.5V 1.5V COMP8 COMP3 - To SOLR1 OLR2 - OLR1 SOLR2 + + 6V Max. 1.75V 6V Min. 0.25V + BCT Vcc COMP5 To SBurst1 Vb 10uA - CSS Css - COMP10 6.5V To SBurst2 (Max.+Min.) of BCt + Max. 1.75V Min. 0.25V 2 + FAN7548 Pin Assignments 20 19 18 17 16 15 14 13 12 11 8 9 10 FAN 7 5 4 8 1 2 3 4 5 6 7 Pin Definitions No Name 1 BDIM Function Description No Name Function Description Burst Dimming Input 11 OUT2 Gate Dirve Output 2 2 BCT Timing Capacitor for Burst Dimming 12 GND Ground 3 OLP1 Open Lamp Protection 1 13 CSS Capacitor for Soft Start 4 VFB1 Error Amp Input 1 14 OSC2 Main Oscillator 2 5 COMP1 Error Amp Output 1 15 OLR2 Open Lamp Regulation 2 6 OLR1 Open Lamp Regulation 1 16 COMP2 7 OSC1 Main Oscillator 1 17 VFB2 Error Amp Input 2 8 ENA ON/OFF Control Input 18 OLP2 Open Lamp Protection 2 9 VCC Power Supply 19 ADIM Analog Dimming Input 10 OUT1 Gate Drive Output 1 20 V3 3V Reference Voltage Error Amp Output 2 3 FAN7548 Absolute Maximum Ratings Vcc=12V, Ta=25°C for typical values and -25°C ≤ Ta ≤ 85°C and 9V ≤Vcc ≤ 30V for min/max values, unless otherwise specified. Characteristics Symbol Value Unit Supply Voltage VCC 6~30 V Operating Temperature Range Topr -25 ~ 85 °C Storage Temperature Range Tstg -65 ~ 150 °C Thermal Resistance Junction-Air (Note1,2) RθJA 112 °C/W Pd 1.1 W Power Dissipation Note: 1. Thermal resistance test board Size: 76.2mm * 114.3mm * 1.6mm(1S0P) JEDEC standard: JESD51-3, JESD51-7 2. Assume no ambient airflow 4 FAN7548 Electrical Characteristics Vcc=12V, Ta=25°C for typical values and -25°C ≤ Ta ≤ 85°C and 9V ≤Vcc ≤ 30V for min/max values, unless otherwise specified. Characteristics Symbol Test Condition Min. Typ. Max. Unit Von - 0.7 - 1.7 V 8.5 10 11.5 uA 5.5 6.5 7.5 V - 100 300 uA 4.7 5.2 5.7 V 7 10 13 mA ON/OFF SECTION On Stage Input Voltage SOFT START SECTION Soft Start Charging Current Soft Start Clamping High Voltage Iss Css=4V Vssh - UVLO SECTION Start Up Current Ist Start Threshold Voltage Vst Operating Supply Current Iop Vcc=4.5V Vcc=12V REFERENCE SECTION 3V Reference Voltage V3 - 2.88 2.98 3.08 V Refrence Voltage Vref - 2.425 2.5 2.575 V ERROR AMP SECTION Output Sink Current lsin COMP=3V - - -2 mA Output Source Current lsur COMP=3V 2 - - mA Ct=150n 93 110 127 Hz BURST OSCILLATOR SECTION Operating Frequency Fbosc Osc High Voltage Vbh - - 1.75 - V Osc Low Voltage Vbl - - 0.25 - V Open Lamp Regulation Voltage Vor - 5.5 6 6.5 V Open Lamp Protection Voltage Vpr - 2 2.5 3 V Open Lamp Protection Current Ipr - - 2.5 - uA PROTECTION SECTION OUTPUT SECTION Output High Voltage Voh Vcc=12V 10 - - V Output Low Voltage Vol Vcc=12V - - 0.2 V 13.5 15.5 V Output Clamping High Voltage Voch VCC = 15V 11.5 Output Voltage with UVLO Activated Vuv VCC = 4V 2 - 4 V Rising Time Tr VCC = 12V - 150 200 ns Falling Time Tf VCC = 12V - 100 150 ns 5 FAN7548 Typical Characteristics On Stage Input Supply Voltage 1.8 Soft Start Charging Current 11.2 1.6 10.5 Iss[uA] Von[V] 1.4 1.2 1.0 9.8 9.1 0.8 -60 -40 -20 0 20 40 60 80 100 120 140 -60 -40 -20 0 40 60 80 100 120 140 120 140 120 140 Figure 2. Soft Start Changing Current Figure 1. On Stage Input Supply Voltage Soft Start Clamping High Voltage Start Up Current 200 7.14 160 6.72 120 Ist[uA] Vssch[V] 20 Temparature['C] Temparature['C] 6.30 80 40 5.88 0 -60 -40 -20 0 20 40 60 80 100 120 140 -60 -40 -20 0 Temparature['C] 20 40 60 80 100 Temparature['C] Figure 4. Start Up Current Figure 3. Soft Start Clamping High Voltage Startup Thresh hold Voltage Operating Supply Current 13.0 5.6 11.7 Iop[mA] Vst[V] 5.4 5.2 10.4 9.1 5.0 7.8 4.8 -60 -40 -20 0 20 40 60 80 100 Temparature['C] Figure 5. Startup Thresh Hold Voltage 6 120 140 -60 -40 -20 0 20 40 60 80 100 Temparature['C] Figure 6. Operating Supply Current FAN7548 Typical Characteristics (Continued) 3.04 8.5 3.00 6.8 Isin1[mA] V3[V] Output Sink Current 1 3V Reference Voltage 3.08 2.96 2.92 5.1 3.4 2.88 -60 -40 -20 0 20 40 60 80 100 120 -60 140 -40 -20 0 40 60 80 100 120 140 120 140 Figure 8. Output Sink Current 1 Figure 7. 3V Reference Voltage Output Sink Current 2 Output Source Current 1 -8.5 8.5 -6.8 6.8 Isin2[mA] Isur1[mA] 20 Temparature['C] Temparature['C] -5.1 5.1 3.4 -3.4 -60 -40 -20 0 20 40 60 80 100 120 -60 140 -40 -20 0 20 40 60 80 100 Temparature['C] Temparature['C] Figure 9. Output Source Current 1 Figure 10. Output Sink Current 2 Output Source Current 2 Operating Frequency 126 -8.5 -6.8 Fbosc[Hz] Isur2[mA] 119 -5.1 -3.4 112 105 98 -60 -40 -20 0 20 40 60 80 100 Temparature['C] Figure 11. Output Source Current 2 120 140 -60 -40 -20 0 20 40 60 80 100 120 140 Temparature['C] Figure 12. Operating Frequency 7 FAN7548 Typical Characteristics (Continued) OSC High Voltage OSC Low Voltage 0.30 1.9 0.28 1.8 0.26 Vbl[V] Vbh[V] 2.0 1.7 0.24 0.22 1.6 0.20 1.5 -60 -40 -20 0 20 40 60 80 100 120 -60 140 -40 -20 0 Temparature['C] 20 40 60 80 100 120 140 100 120 140 Temparature['C] Figure 13. OSC High Voltage Figure 14. OSC Low Voltage Open Lamp Regulation Voltage 1 Open Lamp Protection Voltage 1 3.0 6.46 2.8 6.27 2.6 Vpr1[V] Vor1[V] 6.08 5.89 2.4 2.2 5.70 5.51 2.0 -60 -40 -20 0 20 40 60 80 100 120 -60 140 -40 -20 0 40 60 80 Figure 16. Open Lamp Protection Voltage 1 Figure 15. Open Lamp Regulation Voltage 1 Open Lamp Protection Current 1 3.0 20 Temparature['C] Temparature['C] Open Lamp Regulation Voltage 2 6.46 2.8 6.27 6.08 Vor2[V] Ipr1[uA] 2.6 2.4 2.2 5.70 5.51 2.0 -60 -40 -20 0 20 40 60 80 100 120 Temparature['C] Figure 17. Open Lamp Protection Current 1 8 5.89 140 -60 -40 -20 0 20 40 60 80 100 120 Temparature['C] Figure 18. Open Lamp Regulation Voltage 2 140 FAN7548 Typical Characteristics (Continued) Open Lamp Protection Voltage 2 Open Lamp Protection Current 2 3.0 2.8 2.8 2.6 2.6 Ipr2[uA] Vpr2[V] 3.0 2.4 2.2 2.4 2.2 2.0 2.0 -60 -40 -20 0 20 40 60 80 100 120 140 -60 -40 -20 0 Temparature['C] 20 40 60 80 100 120 140 Temparature['C] Figure 20. Open Lamp Protection Current 2 Figure 19. Open Lamp Protection Voltage 2 Output High Voltage 1 Output Low Voltage 1 0.8 12.40 0.4 Vol1[V] Voh1[V] 11.78 11.16 0.0 -0.4 10.54 -0.8 -60 -40 -20 0 20 40 60 80 100 120 -60 140 -40 -20 0 20 40 60 80 100 120 140 120 140 Temparature['C] Temparature['C] Figure 21. Output High Voltage 1 Figure 22. Output Low Voltage 1 Output Clamping High Voltage 1 Output Voltage with UVLO Activated 1 4.0 15.00 3.8 14.25 Vuv1[V] Voch1[V] 3.6 13.50 3.4 12.75 3.2 12.00 3.0 -60 -40 -20 0 20 40 60 80 100 120 Temparature['C] Figure 23. Output Clamping High Voltage 1 140 -60 -40 -20 0 20 40 60 80 100 Temparature['C] Figure 24. Output Voltage with UVLO Activated 1 9 FAN7548 Typical Characteristics (Continued) Output Low Voltage 2 Output High Voltage 2 0.8 12.40 0.4 Vol2[V] Voh2[V] 11.78 11.16 0.0 -0.4 10.54 -0.8 -60 -40 -20 0 20 40 60 80 100 120 140 -60 -40 -20 0 Temparature['C] 20 40 60 80 100 120 140 120 140 Temparature['C] Figure 25. Output High Voltage 2 Figure 26. Output Low Voltage 2 Output Clamping High Voltage 2 Output Voltaeg with UVLO Activated 2 4.0 15.00 3.8 14.25 Vuv2[V] Voch2[V] 3.6 13.50 3.4 12.75 3.2 12.00 3.0 -60 -40 -20 0 20 40 60 80 100 120 Temparature['C] Figure 27. Output Clamping High Voltage 2 10 140 -60 -40 -20 0 20 40 60 80 100 Temparature['C] Figure 28. Output Voltage with UVLO Activated 1 FAN7548 Mechanical Dimensions Package Dimensions in millimeters 20-SSOP 11 FAN7548 Ordering Information Product number Package Operating Temperature FAN7548G 20-SSOP -25°C ~ 85°C DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. 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