LCD Backlight Inverter Drive IC

FAN7311B LCD Backlight Inverter Drive IC January 2007 FAN7311B LCD Backlight Inverter Drive IC Features High-Efficiency Single-Stage Power Conversion Wide Input Voltage Range: 5V to 25.5V Backlight Lamp Ballast and Soft Dimming Reduced Number of Required External Components Precision Voltage Reference Trimmed to 2% ZVS Full-Bridge Topology Soft-Start Capability PWM Control at Fixed Frequency Analog and Burst Dimming Function Programmable Striking Frequency Open-Lamp Protection Open-Lamp Regulation 20-Pin SOIC Description The FAN7311B 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 cold cathode fluorescent lamp (CCFL) and the transformer's characteristics. The FAN7311B uses a new patent-pending phaseshift control. 20-SOIC Applications LCD TV LCD Monitor www.DataSheet4U.com Ordering Information Part Number FAN7311BM FAN7311BMX Package 20-SOIC 20-SOIC Pb-Free Yes Yes Operating Temperature Range -25°C to 85°C Packing Method Rail Tape & Reel Protected by U.S. Patent: 5,652,479; 7,158,390. © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Internal Block Diagram RT max. 2V min. 0.5V 6μA S_S MRT1 OSCILLATOR Output Driver + + Output Control Logic Output Driver Striking Logic OLP S_S 1.4μA UVLO + 2.5V Solr 105μA Voltage Reference & Internal Bias Sburst VIN UVLO + OUTA OUTB PGND OUTC OUTD CT RT1 EA_OUT ADIM EA_IN Error Amp. + Q SET S Q CLR VOLP+α VOLP 2.5V 1.5V OLP R UVLO + Solr 2.5VREF OLR 2V REF - max. 2V min. 0.5V Positive dimming polarity Sburst 85μA Va+α BCT BDIM AGND + + - ENA 1.4V VIN UVLO 5V FAN7311B Rev.00 Figure 1. Functional Block Diagram of FAN7311B © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 2 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Pin Assignments RT1 20 OUTB OUTA 19 18 VIN 17 PGND OUTC 16 15 OUTD 14 CT 13 RT 12 BCT 11 FAN7311B 1 OLP 2 OLR 3 ENA 4 S_S 5 GND 6 REF 7 ADIM 8 BDIM 9 10 EA_IN EA_OUT FAN7311B Rev. 00 Figure 2. Pin Configuration (Top View) Pin Definitions Pin # 1 2 3 4 5 6 7 8 9 10 Name OLP OLR ENA S_S GND REF ADIM BDIM EA_IN EA_OUT Description Open-Lamp Protection Open-Lamp Regulation Enable Input Soft-Start Analog Ground 2.5V Reference Voltage Analog Dimming Input Burst Dimming Input Error Amplifier Input Error Amplifier Output Pin # 11 12 13 14 15 16 17 18 19 20 Name BCT RT CT OUTD OUTC PGND VIN OUTA OUTB RT1 Description Burst Dimming Timing Capacitor Timing Resistor Timing Capacitor NMOSFET Drive Output D PMOSFET Drive Output C Power Ground Supply Voltage PMOSFET Drive Output A NMOSFET Drive Output B Striking Frequency Resistor © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 3 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Absolute Maximum Ratings 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. For typical values, TA=25°C and VIN=12V. For min. and max. values, TA is the operating ambient temperature range with -25°C ≤ TA ≤ 85°C and 5V ≤ VIN ≤ 25.5V, unless otherwise specified. Symbol VIN TA TJ TSTG θJA(1) PD Supply Voltage Parameter Operating Temperature Range Junction Temperature Storage Temperature Range Thermal Resistance Junction-to-Ambient (still air) Power Dissipation Value 5 to 25.5 -25 to 85 150 -65 to 150 70 1.8 Unit V °C °C °C °C/W W Notes: 1. Thermal resistance test board size: 76.2 * 114.3 * 1.6mm (1S0P). JEDEC standard: JESD51-2, JESD51-3. © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 4 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Electrical Characteristics For typical values, TA=25°C and VIN=12V. For min. and max. values, TA is the operating ambient temperature range with -25°C ≤ TA ≤ 85°C and 5V ≤ VIN ≤ 25.5V, unless otherwise specified. Specifications from -25°C to 85°C are guaranteed by design based on final characterization results. Symbol ΔVref V25 Parameter Line Regulation 2.5V Regulation Voltage Test Condition 5 ≤ VIN ≤ 25.5V Min. Typ. 2 Max. 25 2.55 Unit mV V REFERENCE SECTION (Recommend X7R Capacitor) 2.45 TA = 25°C, CT = 270pF, RT = 18kΩ CT = 270pF, RT = 18kΩ Vcth Vctl CT High Voltage CT Low Voltage TA = 25°C, CTB = 10nF, RT=18kΩ CTB = 10nF, RT=18kΩ Vbcth Vbctl Av GBW Veh lsin lsur Iolr Iburst Vfbh ISS Vssh Volp0 Volp1 Volr Iolp Vth Ist Iop Isb BCT High Voltage BCT Low Voltage Open Loop Gain(2) Unit Gain Bandwidth Output Sink Current Output Source Current EA_IN Driving Current on OLR EA_IN Driving Current on Burst Dimming Feedback High Voltage on Burst Dimming R(EA_IN) = 60kΩ Soft-Start Current Soft-Start Clamping Voltage(2) Start at open lamp Normal -> open lamp 2.2 1.3 1.75 0.7 S_S=1V (2) 2.50 OSCILLATOR SECTION (MAIN) fosc Oscillation Frequency 110.4 108 115.0 115 2.0 0.5 119.6 122 V V kHz OSCILLATOR SECTION (BURST) foscb Oscillation Frequency 209.25 206.25 225.00 225.00 2 0.5 80 1.5 EA_IN = 0V EA_OUT = 1.5V EA_OUT = 1.5V 1 75 61 Va+0.1 4 105 85 Va+0.4 6 4 2.5 1.5 2.00 1.4 2.8 1.7 2.25 2.1 5 VIN = Vth-0.2 VIN = 12V VIN = 12V 130 1.5 200 180 4.0 370 135 109 Va+0.7 8 2.00 2.27 2.54 -1 240.75 241.75 V V dB MHz V mA mA µA µA V µA V V V V µA V µA mA µA Hz ERROR AMP SECTION Feedback Output High Voltage SOFT-START SECTION PROTECTION SECTION Open-Lamp Protection Voltage 0 Open-Lamp Protection Voltage 1 Open-Lamp Regulation Voltage Open-Lamp Protection Charging Current Start Threshold Voltage Start-up Current Operating Supply Current Stand-by Current UNDER-VOLTAGE LOCKOUT SECTION Note: 2. These parameters, although guaranteed, are not 100% tested in production. © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 5 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Electrical Characteristics (Continued) For typical values, TA=25°C and VIN=12V. For min. and max. values, TA is the operating ambient temperature range with -25°C ≤ TA ≤ 85°C and 5V ≤ VIN ≤ 25.5V, unless otherwise specified. Specifications from -25°C to 85°C are guaranteed by design based on final characterization results. Symbol ON/OFF SECTION Von Voff Vpdhv Vphlv Vndhv Vndhv Vpuv Vnuv tr tf Parameter On State Input Voltage Off Stage Input Voltage PMOS Gate High Voltage PMOS Gate Low Voltage NMOS Gate Drive Voltage NMOS Gate Drive Voltage Test Condition Min. 2 Typ. Max. 5 0.7 Unit V V V OUTPUT SECTION VIN = 12V VIN = 12V VIN = 12V VIN = 12V VIN-0.3 0.3 200 200 500 500 6.5 VIN VIN-10.5 VIN-8.5 8.5 0 VIN-6.5 10.5 V V V V V ns ns PMOS Gate Voltage with UVLO Activated VIN = Vth-0.2 NMOS Gate Voltage with UVLO Activated VIN = Vth-0.2 Rising Time (3) VIN = 12V, CL=2nF VIN = 12V, CL=2nF Falling Time(3) Min. Overlap Between Diagonal Switches(3) Max. Overlap Between Diagonal Switches(3) MAX./MIN. OVERLAP fosc = 100kHz fosc = 100kHz 0 100 % % DELAY TIME PDR_A/NDR_B(3) PDR_C/NDR_D(3) RT = 18kΩ RT = 18kΩ 450 450 ns ns Note: 3. These parameters, although guaranteed, are not 100% tested in production. © 2007 Fairchild Semiconductor Corporation FAN7311B Rev. 1.0.0 6 www.fairchildsemi.com FAN7311B LCD Backlight Inverter Drive IC Function Description 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 200µA. ENA: Applying voltage higher than 2V to the ENA pin enables operation of the IC. Applying voltage lower than 0.7V to the ENA pin disables 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 6µA current source. Figure 4. Main Oscillator Waveform 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 in Equation 2. fburst = Figure 3. Soft-Start During Initial Operation 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. 3.75 96 ⋅ RT ⋅ CT (2) To avoid visible flicker, the burst dimming frequency should be greater than 120Hz. By comparing the input of BDIM pin with the 0.5~2V triangular wave of the burst oscillator, the PWM pulses for burst dimming. The PWM pulse controls EA_OUT’s voltage by summing 85µA into the EA_IN pin. f op = 19 32 ⋅ RT ⋅ C T (1) © 2007 Fairchild