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Document overview
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Technical content
Features
Single-Channel Boost LED Switch Internal Power MOSFET for PWM Dimming: RDS(on) = 3.4Ω at VGS=10V, BVDSS=400V Current Mode PWM Control Internal Programmable Slope Compensation Wide Supply Voltage Range: 10V to 35V LED Current Regulation: ±1% Programmable Switching Frequency Analog and PWM Dimming Wide Dimming Ratio: On Time=10µs to DC Cycle-by-Cycle Current Limiting Thermal Shutdown: 150°C Open-LED Protection (OLP) Over-Voltage Protection (OVP) Over-Current Protection (OCP) Error Flag Generation (for External Load Switch) Internal Soft-Start 16-Lead SOIC Package
Applications
LED Backlight for LCD TV LED Backlight for LCD Monitor LED Lighting
Description
The FAN7340 is a single-channel boost controller that integrates an N-channel power MOSFET for PWM dimming using Fairchild’s proprietary planar Double- diffused MOS (DMOS) technology. The IC operates as a constant-current source for driving high-current LEDs. It uses Current Mode control with programmable slope compensation to prevent subharmonic oscillation. The IC provides protections incl uding: open-LED protection, over-voltage protection, and direct-short protection for high system reliability. The IC internally generates a FAULT signal with delay if an abnormal LED string condition occurs. PWM dimming and analog dimming functions can be implemented independently. Internal soft-start prevents inrush current flowing into output capacitor at startup.
Ordering Information
-40°C to +125°C 16-Lead, Small-Ou tline Integrated Circuit (SOIC) Rail FAN7340MX Tape & Reel
Figure 1. Internal Block Diagram
Figure 2. Package Diagram 1 VCC This pin is the supply voltage of the IC. 2 DRV This pin is the gate driv e signal of the boost switch. 3 GND This pin is the ground of the IC. series resistor of this pin. 5 REF This pin is the 5V reference voltage pin. Maximum current capability is 3mA. protection is occurred, the FAULT pin is pulled HIGH. 7 RT Oscillator frequency set of the boost switch (50kHz ~ 300kHz).
8 SENSE
9, 10 DRAIN Drain pin of PWM dimming power MOSFET. voltage of this pin is lower than 1.15V, the IC stops operating. through a resistor divider circuit. If this pin voltage is higher than 3V, OVP is triggered. connected to this pin from the ground. positive inputs of the internal error amplifier. Linear voltage range of ADIM is 0.3V~3.0V. MOSFET is turned on. If this pin voltage is LOW, the dimming MOSFET is turned off.
- Pin 11 is a “No Connect” pin (not shown in Figure 2).
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN7340 • 1.0.0 4 FAN7340 — LED Backlight Driving Boost Switch Absolute Maximum Ratings Stresses exceeding the absolute maximum ratings may damage the device. The devic e may not function or be operable above the recommended operating conditions and stressi ng 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. TA=25C unless otherwise specified. Symbol Parameter Min. Max. Unit VCC Supply Voltage 10 35 V TA Operating Temperature Range -40 +125 C TJ Junction Temperature +150 C TSTG Storage Temperature Range -65 +150 C ӨJA Thermal Resistance Junction-to-Ambient (2, 3) 120 C/W PD Power Dissipation 0.9 W Notes: 3. Assume no ambient airflow. Pin Breakdown Voltage Pin # Name Value Unit Pin # Name Value Unit
1 VCC 35 V 9 DRAIN 400 V
2 DRV 20 V 10 DRAIN 400 V
3 GND V 11 N/A V
4 CS 6 V 12 ENA 6 V
5 REF 6 V 13 OVP 6 V
6 FAULT 35 V 14 CMP 6 V
7 RT 6 V 15 ADIM 6 V
8 SENSE 6 V 16 BDIM 6 V
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN7340 • 1.0.0 5 FAN7340 — LED Backlight Driving Boost Switch
Electrical Characteristics
For typical values, T A = 25°C and V CC = 15V unless otherwise specified. Specifications to -40°C ~ 125°C are guaranteed by design based on final characterization results. Symbol Parameter Condition Min. Typ. Max. Unit Supply Voltage Section VCC Input DC Supply Voltage Range (4) 10 35 V ISD Shutdown Mode Supply Current BDIM Connected to GND 2 4 mA Under-Voltage Lockout Section Vth Start Threshold Voltage 8.3 9.0 9.7 V Vth,hys Start Threshold Voltage Hysteresis 0.5 1.0 1.5 V Ist Standby Current V CC=Vth-0.2 200 300 μA ON/OFF Section Von On-State Input Voltage 2 5 V Voff Off-State Input Voltage 0.8 V Error Amplifier Section Gm Error Amplifier Transconductance (4) V ADIM=1V 100 300 500 µmho AV_ro Error Amplifier Output impedance (4) 20 M Ω AV Error Amplifier Open-Loop Gain (4) 60 dB Voffset Input Offset Voltage V ADIM=1V -10 10 mV Isin CMP Sink Current V ADIM=1V, VSENSE=2V 100 200 300 µA Isur CMP Source Current V ADIM=1V, VSENSE=0V 100 200 300 µA VIDR Input Differential Voltage Range 0 3 V VO Output Voltage Range 0.7 4.0 V Oscillator Section fosc Boost Oscillator Frequency Min. 50 kHz RT=100kΩ 190 200 210 kHz Max. 300 kHz Dmax Maximum Duty Cycle (4) 86 90 94 % Reference Section VREF 5V Regulation Voltage 4.9 5.0 5.1 V VREF,Line 5V Line Regulation 25 mV VREF,Load 5V Load Regulation 0<I5<3mA 25 mV PWM Dimming Section VPDIM,L PWM Dimming Input Low Voltage 0.8 V VPDIM,H PWM Dimming Input High Voltage 2 5 V RPDIM PWM Dimming Pull-Down Resistance 100 160 220 k Ω FET Section (for Dimming) BVDSS Drain-Source Breakdown Voltage (4) VCC=0V, ID=250μA 400 V IDSS Zero-Gate-Voltage Drain Current (4) VDS=250V, TA=25°C 1 30 µA RDS(ON) Drain-Source On-State Resistance V GS=10V, ID=1A 3.4 Ω CISS Input Capacitance (4) VDS=25V, VGS=0V, f=1MHz 173 225 pF COSS Output Capacitance (4) VDS=25V,VGS=0V, f=1MHz 30 40 pF Continued on the following page…
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN7340 • 1.0.0 6 FAN7340 — LED Backlight Driving Boost Switch Electrical Characteristics (Continued) For typical values, T A = 25°C and V CC = 15V, unless otherwise specified. Specifications to -25°C ~ 85°C are guaranteed by design based on final characterization results. Symbol Parameter Condition Min. Typ. Max. Unit Output Section (Boost / Dimming) VDRV Gate Output Voltage V CC=15V 10.8 11.8 12.8 V Vuv Gate Output Voltage Befo re Startup -0.5 0.5 V Idsur Gate Output Drive Source Current (4) 80 180 280 mA Idsin Gate Output Drive Sink Current (4) 80 180 280 mA trh Gate Output Rising Time (Boost) (4) CL=2.0nF 200 ns tfl Gate Output Falling Time (Boost) (4) CL=2.0nF 120 ns Current Sense Section tblank Leading-Edge Blanking (4) 150 300 450 ns tdelay,cl Delay to Output of Current-Limit Comparator(4) 180 ns Voffset,clc Offset Voltage of Current-Limit Comparator(4) -20 20 mV Slope Compensation Section Islope Ramp Generator Current 36 45 54 µA Rslope Slope Compensation Resistor (4) 5 k Ω Soft-Start Section tss Soft-Start Period (4) fosc=200kHz 3 ms Protection Section td,ovp.tr Delay for Triggering Over-Voltage Protection(4) 15 20 25 µs td,ovpr Delay for Releasing Over-Voltage Protection(4) 10 14 18 µs td.ocp Delay for Over-Current Protection (4) 1 µs tAR Auto-Restart Time for Over-Current Protection(4) fosc=200kHz 640 µs td,olpi Delay for Triggering Open-LED Protection (4) 3 5 7 µs td,olp Delay for Open-LED Protection fosc=200kHz 40.96 ms Vth,ovp Over-Voltage Protection Threshold Voltage 2.85 3.00 3.15 V Vhys,ovp Over-Voltage Protection Voltage Hysteresis 0.1 V Vth.csocp Boost Switch Current Limit Threshold Voltage 0.45 0.50 0.55 V Vth,ocp LED Over-Current Protection Threshold Voltage 1.4 (Min. Clamp) 4.0xVADIM 4.0 (Max. Clamp) V Vth,olp Open-LED Protection Threshold Voltage (4) 0.15 0.20 0.25 V TSD Thermal Shutdown Temperature (4) 140 150 160 °C THYS Thermal Shutdown Hysteresis (4) 20 °C Notes: 4. These parameters, al though guaranteed, are not tested in production.
inrush current flowing into output capacitor at startup. Circuit operation is explained in the following sections. established ,up to predetermined threshold level. control inrush current and overshoot. Figure 26. Soft-Start Waveforms current precisely, consider the wire bonding resistor. backlight during the extremely short period of time. 0.1% dimming duty cycle at 200Hz dimming frequency. LEDs with normal peak current level.
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN7340 • 1.0.0 SLC1012C — LED Backlight Driving Boost Switch Typical Application Circuit (Boost Topology for LED Backlight) Application Input Voltage Range Rated Output Power Output current (Rated Voltage) LED LED Backlight TV 120VDC 10% 250mA (230V) 72-LEDs/1-String High Efficiency Constant Current Boost Converters High-Voltage, High-Current LED Driving Typical Application Circuit Figure 35. Typical Application Circuit
Figure 36. 16-Lead, Small Outline Integrated Circuit (SOIC) specifically the warranty therein, which covers Fairchild products. http://www.fairchildsemi.com/packaging/. MS-012, VARIATION AC, ISSUE C. B) ALL DIMENSIONS ARE IN MILLIMETERS. F) DRAWING FILE NAME: M16AREV12.
1.75 MAX
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN7340 • 1.0.0 16 FAN7340 — LED Backlight Driving Boost Switch