FAN7311 LCD Backlight Inverter Drive IC Features Description • High-Efficiency Single-Stage Power Conversion The FAN7311 provides all the control functions for a series parallel resonant converter as well as a pulse width modulation (PWM) controller to develop a supply voltage. Typical operating frequency range is between 30kHz and 250kHz, depending on the CCFL and the transformer's characteristics. The FAN7311 uses a new patent-pending phase-shift control. • Wide Input Voltage Range : 5V to 25.5V • Back Light Lamp Ballast and Soft Dimming • Reduces Number of Required External Components • Precision Voltage Reference Trimmed to 2% • ZVS Full-Bridge Topology 20-SSOP • Soft Start • PWM Control at Fixed Frequency • Analog and Burst Dimming Function • Programmable Striking Frequency 1 • Open Lamp Protection • Open Lamp Regulation • 20-Pin SSOP ©2005 Fairchild Semiconductor Corporation FAN7311 Rev. 1.0.0 1 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC May 2005 RT OUTA OSCILLATOR Output Driver max. 2V OUTB CT min. 0.5V Output Control Logic + + 6uA PGND OUTC S_S RT1 Output Driver OUTD MRT1 Striking Logic OLP S_S 1.4uA EA_OUT UVLO ADIM + + Q Error Amp. - CLR UVLO R 2.5V Solr BCT min. 0.5V VOLP 2.5V 1.5V + OLR Voltage Reference & Internal Bias - 2V 2.5VREF REF + Sburst BDIM - + 1.4V VIN UVLO - 2 FAN7311 Rev. 1.0.0 ENA VIN + AGND OLP Solr 105uA Sburst 85uA Va+α max. 2V VOLP+α S Q EA_IN SET UVLO 5V www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Internal Block Diagram FAN7311 LCD Backlight Inverter Drive IC Pin Assignments RT1 OUTB OUTA VIN PGND OUTC OUTD CT RT BCT 20 19 18 17 16 15 14 13 12 11 9 10 FAN7311 1 2 3 4 5 6 7 8 OLP OLR ENA S_S GND REF ADIM BDIM EA_IN EA_OUT Pin Definitions No Name Function/Description No Name Function/Description 1 OLP Open Lamp Protection 11 BCT 2 OLR Open Lamp Regulation 12 RT Timing Resistor Burst Dimming Timing Capacitor 3 ENA Enable Input 13 CT Timing Capacitor 4 S_S Soft Start 14 OUTD NMOSFET Drive Output D 5 GND Analog Ground 15 OUTC PMOSFET Drive Output C 6 REF 2.5V Reference Voltage 16 PGND Power Ground 7 ADIM Analog Dimming Input 17 VIN Supply Voltage 8 BDIM Burst Dimming Input 18 OUTA PMOSFET Drive Output A 9 EA_IN Error Amplifier Input 19 OUTB NMOSFET Drive Output B 10 EA_OUT Error Amplifier Output 20 RT1 Striking Frequency Resistor 3 FAN7311 Rev. 1.0.0 www.fairchildsemi.com For typical values Ta=25°C, Vcc=12V and for min/max values Ta is the operating ambient temperature range with -25°C ≤ Ta ≤ 85°C and 5V ≤ Vcc ≤ 25.5V, unless otherwise specified. Symbol Value Supply Voltage Characteristics VCC 5 ~ 25.5 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 Unit 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 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Absolute Maximum Ratings For typical values Ta=25°C, Vcc=12V and for min/max values Ta is the operating ambient temperature range with -25°C ≤ Ta ≤ 85°C and 5V ≤ Vcc ≤ 25.5V, unless otherwise specified. Characteristics Symbol Test Condition Min. Typ. Max. Unit REFERENCE SECTION ( Recommend X7R Capacitor ) Line Regulation 2.5V Regulation Voltage ∆Vref 5 ≤ VCC ≤ 25.5V - 2 25 mV 2.45 2.5 2.55 V Ta = 25°C, Ct = 270pF Rt = 18k 108 115 122 Ct = 270pF, Rt = 18k 106 115 124 V25 - OSCILLATOR SECTION(MAIN) Oscillation Frequency fosc kHz CT High Voltage Vcth - - 2.0 - V CT Low Voltage Vctl - - 0.5 - V OSCILLATOR SECTION(BURST) Oscillation Frequency foscb 195 225 255 Hz BCT High Voltage Vbcth Ctb = 10nF, Rt=18k - - 2 - V BCT Low Voltage Vbctl - - 0.5 - V Open Loop Gain - - 80 - dB Unit Gain Bandwidth - - 1.5 - MHz 2.0 2.27 2.54 V ERROR AMP SECTION Feedback Output High Voltage Veh EA_IN = 0V Output Sink Current lsin EA_OUT = 1.5V - - -1 mA Output Source Current lsur EA_OUT = 1.5V 1 - - mA EA_IN Driving Current On OLR Iolr 75 105 135 uA EA_IN Driving Current On Burst Dimming Iburst Feedback High Voltage On Burst Dimming Vfbh R(EA_IN) = 60kΩ 61 85 109 uA Va+0.1 Va+0.4 Va+0.7 V 4 6 8 uA - 5 - V SOFT START SECTION Soft Start Current Soft Start Clamping Voltage ISS S_S=2V Vssh - PROTECTION SECTION Open Lamp Protection Voltage 0 Volp0 Start at open lamp 2.2 2.5 2.8 V Open Lamp Protection Voltage 1 Volp1 Normal -> open lamp 1.3 1.5 1.7 V Open Lamp Regulation Voltage Volr - 1.75 2 2.25 V Open Lamp Protection Charging Current Iolp - 0.7 1.4 2.1 uA - UNDER VOLTAGE LOCK OUT SECTION Start Threshold Voltage Vth - - 5 V Start Up Current Ist VCC = Vth-0.2 - 130 180 uA Operating Supply Current Iop VCC = 12V - 1.5 4 mA Stand-by Current Isb VCC = 12V - 200 370 uA ON/OFF SECTION On State Input Voltage Von - 2 - 5 V Off Stage Input Voltage Voff - - - 0.7 V 5 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Electrical Characteristics For typical values Ta=25°C, Vcc=12V and for min/max values Ta is the operating ambient temperature range with -25°C ≤ Ta ≤ 85°C and 5V ≤ Vcc ≤ 25.5V, unless otherwise specified. Characteristics Symbol Test Condition Min. Typ. Max. Unit OUTPUT SECTION PMOS Gate High Voltage Vpdhv VCC = 12V - Vcc - V PMOS Gate Low Voltage Vphlv VCC = 12V Vcc-10.5 Vcc-8.5 Vcc-6.5 V NMOS Gate Drive Volgate Vndhv VCC = 12V 6.5 8.5 10.5 V NMOS Gate Drive Volgate Vndhv VCC = 12V - 0 - V PMOS Gate Voltage With UVLO Activated Vpuv VCC = Vth-0.2 Vcc-0.3 - - V NMOS Gate Voltage With UVLO Activated Vnuv VCC = Vth-0.2 - - 0.3 V Rising Time Tr VCC = 12V, Cload=2nF - 200 500 ns Falling Time Tf VCC = 12V, Cload=2nF - 200 500 ns Min. Overlap between diagonal switches fosc=100KHz - 0 - % Max. Overlap betwwen diagonal switches fosc=100KHz - 100 - % PDR_A/NDR_B Rt=18k - 450 - ns PDR_C/NDR_D Rt=18k - 450 - ns MAX./MIN OVERLAP DELAY TIME 6 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Electrical Characteristics (Continued) UVLO: The under voltage lockout circuit guarantees stable operation of the IC’s control circuit by stopping and starting it as a function of the Vin value. The UVLO circuit turns on the control circuit when Vin exceeds 5V. When Vin is lower than 5V, the IC’s standby current is less than 200uA. ENA: Applying voltage higher than 2V to the ENA pin enables the operation of the IC. Applying voltage lower than 0.7V to the ENA pin will disable the operation of the inverter. Soft start: The soft start function requires that the S_S pin is connected through a capacitor to GND. A soft start circuit ensures a gradual increase in the input and output power. The capacitor connected to the S_S pin determines the rate at which the duty ratio rises. It is charged by a 6uA current source. Burst oscillator & burst dimming: The timing capacitors (BCTs) are charged by the reference current source, which is formed by the timing resistor (RT). The timing resistor’s voltage is regulated at 1.25V. The sawtooth waveform charges up to 2V. Once this voltage is reached, the capacitors begin discharging down to 0.5V. Next the timing capacitors start charging again and a new switching cycle begins. The burst dimming frequency can be programmed by adjusting the Rt and BCT values. The burst dimming frequency can be calculated as shown below. f burst 3.75 = ----------------------------------64 R T BC T To avoid visible flicker, the burst dimming frequency should be greater than 120Hz. Main oscillator: The timing capacitors (CTs) are charged by the reference current source, which is formed by the timing resistor (RT). The timing resistor’s voltage is regulated at 1.25V. The sawtooth waveform charges up to 2V. Once this voltage is reached, the capacitors begin discharging down to 0.5V. Next, the timing capacitors start charging again and a new switching cycle begins. The main frequency can be programmed by adjusting the Rt and CT values. The main frequency can be calculated as shown below. What does the following sentence mean? Please rewrite.To compare the input of BDIM pin with the 0.5~2V triangular wave of burst oscillator makes the PWM pulse for burst dimming. The PWM pulse controls EA_OUT’s voltage by summing 85uA into the EA_IN pin. 19 f op = ------------------------------32 R T C T 7 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Function Description 8.5V 8.5V VIN 8.5V 8.5V Open lamp regulation & open lamp protection: It is necessary to suspend power stage operation if an open lamp occurs, because the power stage has high gain. When a voltage higher than 2V is applied to the OLR pin, the part enters regulation mode and controls the EA_OUT voltage. This limits the lamp voltage by summing 105uA into the feedback node. At the same time, the OLP capacitor, connected to the OLP pin, is charged by the 1.4uA internal current source. Once it reaches 2.5V, the IC enters shut down where all the output is high. Output Drives: The four output drives are designed so that switches A and B, C and D never turn on simultaneously. The OUTA-OUTB pair is intended to drive one half-bridge in the external power stage. The OUTC-OUTD pair will drive the other half-bridge. 8 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC VIN The FAN7311 uses the improved phase-shift control full-bridge to drive CCFL. As a result, the temperature difference between the left and the right leg is almost zero. The detail timing is shown below. EA_OUT CT SYNC T T1 POUT A NOUT B POUT C NOUT D 9 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Timing Diagram VCC C25 100u IC1 FAN7311 R25 0 0.1u OLR OUTB ENA OUTA S_S VIN C22 1u C8 RT1 0 R26 0 10k 0 10k OUTB R24 ENA C27 1u RT R6 120k OLP OUTA 10k C28 10n 0 REF 0 REF TX1 REF OUTC ADIM OUTD BDIM CT 10u 0 PGND M2 FDS8958A OUTC 1u R2 56k C7 C6 1u GND C2 R4 22k M1 FDS8958A 0 C1 1u 0 0 OUTD C5 220p DIM(0~3.3V) CCFL 0 0 C10 15p R5 27k C21 10n R3 20k EA_IN 0 RT C3 C4 4.7n EA_OUT 0 0 0 OLP1 0 0 BCT OLR 4.7n RT R8 R15 FB FB D4 BAV99 C14 20n D6 BAV99 R16 1.5k 2k 100k R9 8.2k 0 0 0 0 0 OLR R14 C16 100k 2.2n OLP1 OLP R1 330k Q1 KST2222 C9 1u D1 D1N4148 R22 0 0 10k D11 D1N4148 C19 2.2n 0 0 10 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Typical Application Circuits Package Dimensions in millimeters 20-SSOP 11 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC Mechanical Dimensions FAN7311 LCD Backlight Inverter Drive IC Ordering Information Product number FAN7311G FAN7311GX Package Operating Temperature 20-SSOP -25°C ~ 85°C 12 FAN7311 Rev. 1.0.0 www.fairchildsemi.com FAN7311 LCD Backlight Inverter Drive IC 13 FAN7311 Rev. 1.0.0 www.fairchildsemi.com