FAN7346 4-Channel LED Current Balance Controller Features Description Linear Balance Control for 4-Channel LED Arrays Wide LED String Voltage Range: 100V Wide VCC Voltage: 10.5V to 35V External Linear Regulation Switch: MOSFET or BJT Internal Voltage Regulator for Feedback Monitoring Drain-Source Voltage of External Switch Precision Current Accuracy Trimmed to 1.5% Supports External PWM Dimming - Positive Supports Wide Dimming Ratio: 0.5%~100% Adaptive Linear Regulation Method Generate Integrated Feedback Signal for Primary Controller (Current Feedback + PWM Dimming) High Efficiency by Primary Side Direct Feedback Thermal Shutdown (Auto-Recovery) Over-Voltage Regulation Channel Individual Open-LED Protection Channel Individual Short-LED Protection Channel Individual Over-Current Protection Error Flag Output 28-Pin SOIC The FAN7346 is an LED current-balance controller that controls 4-LED arrays to maintain equal LED current. The FAN7346 has a high withstanding voltage, so is suitable for edge-type LED BLU and LED Lighting. To minimize components between primary to secondary, the FAN7346 generates a new integrated feedback signal. The FAN7346 provides various protections, such as over-voltage regulation, open-LED protection, thermal protection, and drain-source voltage protection of regulating switch (the FAN7346 monitors all LED arrays drain-source voltage for protection). To increase system reliability, FAN7346 applies individual string protection. Because FAN7346 integrates so many functions it reduces overall BOM costs. LED brightness can be linearly varied up to LED current by applying an external Pulse Width Modulated (PWM) signal to the PWM pin. The FAN7346 is available in a 28-SOIC package. Applications LED BLU for LCD TV LED BLU for LCD Monitor LED Lighting Ordering Information Part Number FAN7346M FAN7346MX Operating Temperature Package -40 to +125°C 28-Lead, Small-Outline Integrated Circuit (SOIC) © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 Packing Method Rail Tape & Reel www.fairchildsemi.com FAN7346 — 4-Channel LED Current Balance Controller May 2011 FAN7346 — 4-Channel LED Current Balance Controller Block Diagram Figure 1. Internal Block Diagram © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 2 Figure 2. Package Diagram Pin Definitions Pin # Name Description 1 OVR 2 FB 3 CMP This pin is for compensation of the minimum channel voltage feedback. 4 VMIN Synchronous signal of channel drain-voltage. If multiple controllers are operated, this pin must be tied together. In single operation, this pin must be open. 5 FO 6 PWM4 PWM dimming signal input pin of channel 4. 7 PWM3 PWM dimming signal input pin of channel 3. 8 PWM2 PWM dimming signal input pin of channel 2. 9 PWM1 PWM dimming signal input pin of channel 1. This pin is input for over-voltage regulation. This pin is for feedback of minimum drain voltage of external current regulation switch. This pin is externally connected to the cathode of the feedback photo-coupler. This pin is fault output. In case of OLP, SLP, and OCP; this pin is connected to ground. 10 ENA Enable input. 11 ADIM This pin is for the reference voltage of the LED current feedback voltage. 12 SLPR This pin is for setting the reference of channel over-voltage protection (short-LED protection). 13 REF This pin is the reference output. Voltage is 5V; current capability is 3mA. 14 VCC This pin is the supply voltage of the controller. 15 FB4 This pin is for current sensing feedback of channel 4. 16 VDD Internal gate driver power supply voltage. A large capacitor (1µF~2µF) must be connected from this pin to ground. 17 OUT4 This pin is for gate signal to the external balance FET of channel 4. 18 CH4 This pin is for drain voltage of the external balance FET of channel 4. 19 FB3 This pin is for current sensing feedback of channel 3. 20 OUT3 21 CH3 This pin is for drain voltage of the external balance FET of channel 3. 22 FB2 This pin is for current sensing feedback of channel 2. 23 OUT2 24 CH2 This pin is for drain voltage of the external balance FET of channel 2. 25 FB1 This pin is for current sensing feedback of channel 1. 26 OUT1 27 CH1 This pin is for drain voltage of the external balance FET of channel 1. 28 GND This pin is the ground. This pin is for gate signal to the external balance FET of channel 3. This pin is for gate signal to the external balance FET of channel 2. This pin is for gate signal to the external balance FET of channel 1. © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 3 FAN7346 — 4-Channel LED Current Balance Controller Pin Configuration 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 Parameter Min. Max. Unit VIN IC Supply Voltage 10.5 35.0 V TA Operating Temperature Range -40 +125 C TJ Operating Junction Temperature +150 C +150 C 70 C/W 1.4 W TSTG Storage Temperature Range -65 θJA Thermal Resistance Junction-Air PD Power Dissipation (1,2) Notes: 1. Thermal resistance test board. Size: 76.2mm x 114.3mm x 1.6mm (1S0P); JEDEC standard: JESD51-2, JESD51-3. 2. Assume no ambient airflow. Pin Breakdown Voltage Pin # Name Value 1 OVR 6 15 FB4 6 2 FB 6 16 VDD 17 3 CMP 6 17 OUT4 17 4 VMIN 6 18 CH4 100 5 FO 6 19 FB3 6 6 PWM4 6 20 OUT3 17 7 PWM3 6 21 CH3 100 8 PWM2 6 22 FB2 6 9 PWM1 6 23 OUT2 17 10 ENA 6 24 CH2 100 11 ADIM 6 25 FB1 6 12 SLPR 6 26 OUT1 17 13 REF 6 27 CH1 100 14 VCC 35 28 GND © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 Unit Pin # V Name Value Unit V www.fairchildsemi.com 4 FAN7346 — 4-Channel LED Current Balance Controller Absolute Maximum Ratings For typical values; TA = 25°C, VIN = 12V, and -25°C TA 85°C, 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 Start Threshold Voltage 8.5 9.5 10.5 V Start Threshold Voltage Hysteresis 0.5 1.0 1.5 V 100 300 µA 1 3 mA 5.0 V 0.7 V Under-Voltage Lockout Section (UVLO) Vth Vthhys Ist Startup Current VIN=8V Iop Operating Supply Current VIN=12V, Not Switching ON/OFF Section Von On-State Input Voltage Voff Off-Stage Input Voltage RENA 1.4 Pull-Down Resistor 130 200 270 kΩ 4.9 5.0 5.1 V Reference Section (Recommend 1µF X7R Capacitor) VREF 5V Regulation Voltage IREF=0mA VR-LINE 5V Line Regulation 10 VIN 35V 50 mV VR-LOAD 5V Load Regulation 0 IREF 3mA 50 mV 8.5V Regulation Voltage VIN=12V 8.0 8.5 9.0 V 194 200 206 mV VDD LED Current Section VFBX CH LED Current Reference Voltage VADIM=2V VLREF LED Current Reference Voltage 0.5V VADIM 4V VADIM /10 V VADIM-CLAMPH ADIM Voltage HIGH Clamping Voltage VIN=12V 3.84 4.00 4.16 VADIM-CLAMPL ADIM Voltage LOW Clamping Voltage VIN=12V 0.45 0.50 0.55 VADIM=2V -1.5 BCH Current Balance Between Channels V 1.5 % 1.05 V Headroom Voltage Feedback Section VFBR Feedback Reference Voltage Ileak Channel Leakage Current (3) 0.95 1.00 PWM ON, VCH=1V 0 100 µA PWM OFF, VCH=30V 0 2 µA AV Open-Loop Gain VVMIN=1V 65 dB Gm Error Amplifier Transconductance VVMIN=1.5V 140 180 220 µmho lsin Output Sink Current VVMIN=0V 70 120 170 µA lsur Output Source Current VVMIN=2V 70 120 170 µA Continued on the following page… © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 5 FAN7346 — 4-Channel LED Current Balance Controller Electrical Characteristics For typical values; TA = 25°C, VIN = 12V, and -25°C TA 85°C, 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 PWM Dimming Section Vbdim(ON) PWM Dimming On Voltage 2 5 V Vbdim(Off) PWM Dimming Off Voltage 0 0.8 V 100 500 Hz fbdim PWM Dim Input Frequency Range(3) On Duty Ratio=1% tbdimR (3) PWM Dim On Rising Time Ext. Switch Qg=4.3nC 400 ns tbdimF PWM Dim Off Falling Time(3) Ext. Switch Qg=4.3nC 150 ns VOVR=1V, ILED: 0 to Maximum 10 ms Soft-Start Section tSS Soft-Start Time(3) Protection Section VTH,OVR OVR Threshold Voltage 1.35 1.42 1.49 VTH,OCP OCP Threshold Voltage 0.95 1.00 1.05 TOCP OCP Shutdown Time(3) VTH,SLP SLP Threshold Voltage TD,SLP (3) 20 µs (3) 20 µs 10 VSLPR=1V 9.5 SLP Delay TD,OLP OLP Delay VTH,OLP OLP Threshold Voltage 0.27 10.0 0.30 V V µs 10.5 0.33 V V TTRIP Internal Thermal Protection (3) Threshold 150 °C TTYH Internal Thermal Protection (3) Hysteresis 25 °C Output Section VGH NMOS Gate High Voltage VIN=12V VGL NMOS Gate Low Voltage VIN=12V NMOS Gate Voltage with UVLO Activated VIN=7V NMOS Gate Drive Source Current VIN=12V 50 NMOS Gate Drive Sink Current VIN=12V 300 VG,UVLO IG,SOURCE IG,SINK 8.0 8.5 9.0 0 V V 0.3 V 150 250 mA 500 700 mA Note: 3. These Parameters, although guaranteed, are not 100% tested in production. © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 6 FAN7346 — 4-Channel LED Current Balance Controller Electrical Characteristics (Continued) 1.6 11 10 1.2 Vthhys [V] 1.4 Vth [V] 10.5 9.5 9 1 0.8 8.5 0.6 8 0.4 -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature [Ԩ] 50 75 100 125 Temperature [Ԩ] Figure 3. Start Threshold Voltage vs. Temperature Figure 4. Start Threshold Voltage Hysteresis vs. Temperature 350 3.5 300 3 250 2.5 Iop [mA] Ist [µA] 25 200 150 100 2 1.5 1 50 0.5 0 0 -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature [Ԩ] 25 50 75 100 125 Temperature [Ԩ] Figure 5. Startup Current vs. Temperature Figure 6. Operating Current vs. Temperature 1.5 300 1.4 Rena [KΩ] Vonth [V] 1.3 1.2 1.1 1 250 200 0.9 150 0.8 0.7 0.6 100 -50 -25 0 25 50 75 100 125 -50 Temperature [Ԩ] 0 25 50 75 100 125 Temperature [Ԩ] Figure 7. Enable Threshold Voltage vs. Temperature © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 -25 Figure 8. Pull-Down Resistor vs. Temperature www.fairchildsemi.com 7 FAN7346 — 4-Channel LED Current Balance Controller Typical Performance Characteristics 5.15 9.2 5.1 9 8.8 VDD [V] VREF [V] 5.05 5 8.6 8.4 4.95 8.2 4.9 8 4.85 7.8 -50 -25 0 25 50 75 100 125 -50 -25 0 25 Temperature [Ԩ] 100 125 Figure 10. 8.5V Regulation Voltage vs. Temperature 8 4.18 6 4.14 VADIM-CLAMPH [V] 4 Vofs [mV] 75 Temperature [Ԩ] Figure 9. 5V Regulation Voltage vs. Temperature 2 0 -2 -4 -6 4.1 4.06 4.02 3.98 3.94 3.9 3.86 -8 -50 -25 0 25 50 75 100 3.82 125 -50 -25 0 Temperature [Ԩ] 25 50 75 100 125 Temperature [Ԩ] Figure 11. Offset of CH LED Current Reference Voltage vs. Temperature Figure 12. ADIM HIGH Clamping Voltage vs. Temperature 0.57 2 0.55 1.5 1 0.53 BCH [%] VADIM-CLAMPL [V] 50 0.51 0.49 0.47 0.5 0 -0.5 -1 0.45 -1.5 0.43 -2 -50 -25 0 25 50 75 100 125 -50 Temperature [Ԩ] 0 25 50 75 100 125 Temperature [Ԩ] Figure 13. ADIM LOW Clamping Voltage vs. Temperature © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 -25 Figure 14. Current Balance Between Channels vs. Temperature www.fairchildsemi.com 8 FAN7346 — 4-Channel LED Current Balance Controller Typical Performance Characteristics (Continued) 1.04 220 1.02 200 Gm [µMho] 240 VFBR [V] 1.06 1 0.98 0.96 180 160 140 0.94 120 -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature [Ԩ] 160 160 140 140 ISUR [µA] ISIN [µA] 180 120 100 80 80 60 60 25 50 75 100 -50 125 -25 0 125 25 50 75 100 125 Temperature [Ԩ] Temperature [Ԩ] Figure 17. Error Amplifier Output Sink Current vs. Temperature Figure 18. Error Amplifier Output Source current vs. Temperature 2.1 1.5 1.9 1.48 1.46 1.7 VTH,OVR [V] Vbdim(th) [V] 100 120 100 0 75 Figure 16. Error Amplifier Transconductance vs. Temperature 180 -25 50 Temperature [Ԩ] Figure 15. Feedback Reference Voltage vs. Temperature -50 25 1.5 1.3 1.44 1.42 1.4 1.1 1.38 0.9 1.36 1.34 0.7 -50 -25 0 25 50 75 100 -50 125 0 25 50 75 100 125 Temperature, [Ԩ] Temperature, [Ԩ] Figure 19. PWM Dimming On Threshold Voltage vs. Temperature © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 -25 Figure 20. OVR Threshold Voltage vs. Temperature www.fairchildsemi.com 9 FAN7346 — 4-Channel LED Current Balance Controller Typical Performance Characteristics (Continued) 10.6 1.1 10.4 VTH,SLP [V] VTH,OCP [V] 1.05 1 10.2 10 9.8 0.95 9.6 9.4 0.9 -50 -25 0 25 50 75 100 -50 125 -25 0 50 75 100 125 Temperature [Ԩ] Temperature [Ԩ] Figure 21. OCP Threshold Voltage vs. Temperature Figure 22. SLP Threshold Voltage vs. Temperature 0.34 9.2 0.33 9 0.32 8.8 0.31 VGH [V] VTH,OLP [V] 25 0.3 8.6 8.4 0.29 8.2 0.28 8 0.27 7.8 0.26 -50 -25 0 25 50 75 100 -50 125 -25 0 25 75 100 125 Temperature [Ԩ] Temperature [Ԩ] Figure 23. OLP Threshold Voltage vs. Temperature Figure 24. NMOS Gate High Voltage vs. Temperature 250 700 200 600 IG,SINK [mA] IG,SOURCE [mA] 50 150 100 50 500 400 300 0 200 -50 -25 0 25 50 75 100 125 -50 Temperature [Ԩ] 0 25 50 75 100 125 Temperature [Ԩ] Figure 25. NMOS Gate Drive Source Current vs. Temperature © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 -25 Figure 26. NMOS Gate Drive Sink Current vs. Temperature www.fairchildsemi.com 10 FAN7346 — 4-Channel LED Current Balance Controller Typical Performance Characteristics (Continued) FAN7346 — 4-Channel LED Current Balance Controller Functional Description The FAN7346 is a high-efficiency 4-channel LED driver. It can drive a 4-channel LED string with four external balance switches. It provides an integrated feedback for a DC-DC controller on the secondary side or on the flyback / LLC controller of the primary side. Due to the high withstanding voltage of the sensing pin for drain voltage of external switch, the FAN7346 can be used in high-voltage LED string operation without any clamping circuit. Both MOSFET and transistor can be used as external balance switch, so the FAN7346 can drive a high-current LED string. For four-string operation, the FAN7346 supports four individual PWM signal input pins. The FAN7346 can be operated by parallel connection mode. For a primary-side direct-power control system, the FAN7346 supports an advanced power sequence and soft-start timing. LED driving voltage can be set before LED ignition for a reliable LED backlight ignition. The FAN7346 supports various and programmable protections; Short-LED Protection (SLP), Open-LED Protection (OLP), Over-Current Protection (OCP), and Over-Voltage Regulation (OVR). Except OCP, all protection are auto-recovery / auto-restart. Except OVR, all protections are channel-individual protection. In case of SLP, OLP and OCP; even if some strings are in protection condition, other strings continues to operating for higher system reliability. Figure 27. Startup Sequence 2. Feedback After soft-start, the FAN7346 starts feedback drainvoltage of external balance switch. Figure 27 shows the work-flow of startup sequence. Drain voltage of each channel is sensed on the CHx pin. CHx means any of the CH1 / CH2 / CH3 / CH4 pins. Minimum drain voltage is selected between four CHx voltages. The FAN7346 feeds back drain voltage to control minimum drain voltage at 1V. 1. Startup When VCC voltage is higher than UVLO threshold voltage, internal 5V regulation output is operated. At the same time, feedback starts to control OVR voltage as 1V. If OVR voltage is lower than 1V, feedback is pulled up. If OVR voltage is higher than 1V, feedback is pulled down. If minimum drain voltage is higher than 1V, FB is pulled LOW. If minimum drain voltage is lower than 1V, FB is pulled HIGH. After enable is applied, the FAN7346 begins soft-start procedure. The FAN7346 checks if OVR voltage is higher than 0.9V. If OVR voltage is lower than 0.9V, softstart function is not started. If OVR voltage is higher than 0.9V, the FAN7346 starts LED current balance and softstart. The LED current of each string is increased gradually for 10ms, which is fixed soft-start timing. During soft-start timing, SLP and OLP are disabled. Feedback response can be controlled by adding a resistor and capacitor to the CMP pin. 3. Analog Dimming In the FAN7346, LED current can be modified by changing ADIM voltage. LED current is controlled by the FBx pin voltage. FBx means any of the FB1 / FB2 / FB3 / FB4 pins. External current balance switch is operating in the saturation region to control LED current. Sensed voltage on the FBx pin is compared with internal reference voltage and the controller supplies a gate / base signal for the external current balance switch. M I D D E IL E S N E S AR V 0 1 Internal reference voltage is decided by ADIM voltage. The formula for LED current calculation is: (1) ADIM voltage is clamped internally from 0.5V to 4V. If ADIM voltage is lower than 0.5V, it is clamped as 0.5V. If ADIM voltage is higher than 4V, it is clamped as 4V. © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 11 If PWM dimming voltage is higher than 2V, an external balance switch is turned on and conducts constant current operation. If PWM dimming voltage is lower than 0.8V, an external balance switch is turned off and blocks LED current. LED Current Output CHx Voltage During PWM dimming off, open-LED protection and short-LED protection is disabled. CHx drain voltage is sampled during PWM dimming on and held during PWM dimming off to maintain drain voltage regardless of dimming on/off signal. 5. Short-LED Protection (SLP) To sense a short-LED condition, the FAN7346 uses the drain voltage of external balance switch. If some LEDs are shorted, its LED forward voltage is lower than other LED strings, so the drain voltage of the external balance switch is higher than other drain voltage. 6. Open LED Protection (OLP) To sensing open-LED condition, the FAN7346 use the drain voltage of an external balance switch. If an LED string is open, the drain voltage of external balance switch is grounded, and the FAN7346 can detect openLED condition. OLP threshold voltage is 0.3V. If CHx voltage is lower than 0.3V for 20µs, its drainvoltage feedback is pulled up to 5V. This means the open LED string is eliminated from minimum drain voltage feedback loop. Without OLP, if minimum drain voltage is 0V, drain voltage feedback forces the FB signal to increase output power. This can cause SLP or thermal stress in other channels. R P L S V * 0 1 H T P L S V SLP Figure 28. Short-LED Protection Operation SLP threshold voltage can be programmed by SLPR (Short-LED Protection Reference) voltage. Internal SLP threshold voltage is calculated as: ︳ SLPR Normal (2) Minimum SLP threshold voltage is 0V and maximum SLP threshold voltage is 45V. SLP is a channel-individual protection. If any string is in SLP condition, the SLP strings is turned off and other string operate normally. OLP is an auto-recovery protection. As soon as drain voltage is higher than 0.3V, OLP is finished and the drain voltage feedback system is restored. If the sensed-drain voltage (CHx voltage) is higher than the programmed threshold voltage for 20µs, CHx goes into short-LED protection, which forces the corresponding channel to turn off. To increase reliability, the SLP channel is restarted in the next PWM dimming signal rising timing. After restarting, the FAN7346 checks the drain voltage. If the drain voltage is higher than the SLP threshold voltage for 20µs, the switch is turned off. If drain voltage is lower, the channel is restored to normal operation. Shorted LED channel operation is minimum duty PWM dimming with a 20µs dimming on period. During 100% full duty PWM dimming, auto restart is not activated. Figure 29 shows the OLP operation. Before open CH2, CH2 is the headroom channel. (CH2 drain voltage is minimum voltage – 1V.) As soon as open CH2, its drain voltage is 0V, OLP is activated, and CH2 is removed from headroom feedback control loop. CH1 is selected as minimum drain voltage channel, so its drain voltage is controlled as 1V. Reconnecting CH2 string, restores normal operation. Figure 28 shows the SLP operation. As soon as SLPR*10 (blue line) is lower than CHx voltage, CHx is forced into minimum duty dimming operation. Output CH2 LED Current CH1 Drain Voltage CH2 Drain Voltage CH2 Open Figure 29. Open-LED Protection Operation © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 12 FAN7346 — 4-Channel LED Current Balance Controller 4. PWM Dimming The FAN7346 has four PWM dimming signal pins. Each PWM dimming pin controls an LED string. current damage. To sense over-current condition, the FAN7346 monitors FBx (FB1~FB4) pin voltage. If FBx voltage is higher than 1V for 20µs, CHx is considered an over-current condition. After sensing OCP condition, CHx dimming switch is turned off. OCP is channel individual and latched protection. If one channel is in OCP condition, other channels keep operating. OCP channel is restarted after UVOL is reset. In FAN7346, OVR voltage uses two kinds of feedback and control: and regulating output voltage during enable off and clamping output voltage during enable on. 9. Error Flag (FO) To make error flag signal, the FAN7346 uses the FO pin. FO pin is open-drain type. When ENA pin is LOW, the FAN7346 controls FB voltage to maintain OVR voltage as 1.0V. Through this output voltage control during ENA off, the FAN7346 reaches adequate LED driving voltage before turning ENA on. During normal operation, the FO pin is open. If using an external pull-up resistor, this signal is HIGH. After ENA pin is HIGH, OVR pin voltage is used for overvoltage regulation. If OVR pin voltage is lower than 1.42V, the FB pin voltage follows headroom control to maintain minimum voltage of drain voltages as 1V. If OVR pin voltage is higher than 1.42V, the FAN7346 controls FB (FB is pulled LOW). Through feedback regulation, OVR pin voltage cannot exceed 1.42V. If used OLP / OCP / SLP protection, the FO pin is connected to ground. If using an external pull-up resistor, this signal is LOW. If a single channel is in protection condition, error-flag signal is detected. Only if all channels are operating normally is the FO pin pulled HIGH. 8. Over-Current Protection (OCP) Through over-current protection, the FAN7346 can protect external balance switches from shorted over- © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 13 FAN7346 — 4-Channel LED Current Balance Controller 7. Over-Voltage Regulation (OVR) To prevent LED driving voltage from exceeding the withstanding voltage of system components, the FAN7346 controls LED driving voltage with OVR pin voltage. The FAN7346 senses output LED driving voltage through the OVR pin voltage. Resistor divided output voltage is applied to the OVR pin voltage. FAN7346 — 4-Channel LED Current Balance Controller Short Lamp Protection Figure 30. Block Diagram of Short LED Protection Figure 31. Timing Diagram of Short LED Protection © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 14 Application Device Input Voltage Range LED String 32~46 Inch LED TV FAN7346 380V 8-String / 90V / 100mA 1 2 3 4 5 6 7 8 9 10 CN3 CON10 Q4 FQT4N25 Q8 FQT4N25 R54 R58 3.9R Q3 FQT4N25 3.9R Q7 FQT4N25 R53 R57 3.9R Q2 FQT4N25 3.9R Q6 FQT4N25 R52 R56 3.9R Q1 FQT4N25 C32 open C31 open C33 open C34 open 3.9R Q5 FQT4N25 R51 C35 open C36 open C37 open C38 open R55 3.9R C14 OUT4 VDD FB4 SLPR REF VCC ENA PWM1 PWM2 PWM3 PWM4 FAN7346 FO 1u CH4 FB3 R58 0R ADIM OUT3 FB2 R57 0R CH3 OUT2 FB1 CH2 VMIN CH1 OUT1 FB OVR 28-SOIC R56 0R CMP GND FB4 VDD IC2 FAN7346 VCC OUT4 REF ADIM ENA PWM1 PWM2 PWM3 FO PWM4 FAN7346 3.9R C20 R55 0R 1u SLPR FB3 R38 0R CH4 OUT3 CH3 OUT2 FB1 CH2 VMIN CH1 OUT1 CMP GND 5V FB OVR REF1 R37 0R FB2 R32 0R R31 0R IC3 FAN7346 28-SOIC VCC2 R19 0R R18 open PWM3 PWM2 PWM1 U2A R17 1 C6 1n 2 1k ZD102 PC817A R9 10k REF1 PWM4 REF1 PWM7 PWM6 PWM5 C19 1n REF2 PWM8 R13 open 100k R25 10k R27 10k SOD-123 C16 1u ENA 1u C10 1n R10 R11 open VCC2 C11 ENA 10k R720R R12 REF2 C22 1n R26100k R28 open R710R C3 open C203 R3 R4 C2 C1 10n 10k R6 R24 open open VCC2 PWM5 PWM6 PWM7 REF1 PWM8 PWM4 R2 12k PWM1 10n R1 1M C202 100uF/200V R23 open PWM2 100k R5 PWM3 100uF/200V open open REF2 C13 22uF/50V C12 C201 1u R14 22R D212 FEP16JT 1 2 3 4 5 6 7 8 9 10 0 ENA 12 9 10 7 11 D211 FEP16JT 8 100uF/200V TM103 EER39HS-16 C4 10n CN6 CON10 6 5 4 3 2 1 R8 10k C102 R7 1k C106 MPE630V223J 1 2 3 2A224K FSFR2100 M101 FDD5N50F M102 FDD5N50F R109 10k R107 3.3R D101 UF4007 CN5 CON3 R110 10k R108 3.3R D101 LMBD914 D102 LMBD914 U1 FAN7621 R113 390k VCC1 0 14.LO 2.CTR 9.CS U4 ZD101 2N2222 10.SG 6.CON U5 2N2907 R112 16.PG FAN7621 8.RT 12.LVcc 3.HO 1.HVcc 16-SOIC R106 10R 6.8V/1N4736 C112 C103 0.33uF/25V 680pF/50V R107 C109 25V/47uF 1.8k R105 R101 0.1R/1W CN6 CON3 100pF/50V R102 C107 3 2 1 C105 10k R114 10k 0 1k 16V / 33uF C108 VCC1 4.7k R109 R110 R111 1M 1M 47k 12nF/100V R104 4 910R 3 U2B PC817A C101 0 220uF/450V F2 FUSE PFC_OUT(380Vdc) Figure 32. LCD Backlight Driver © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 15 FAN7346 — 4-Channel LED Current Balance Controller Typical Application Circuit (Backlight) Application Device Input Voltage Range LED String LED Lighting FAN7346 380V 4-String C123 TM2 D201 C201 VLED C202 C203 VAUX R129 RS8 Q104 R131 R123 R132 R128 C115 R133 D109 Q103 U102 R130 D202 LVCC VDL CS6 RS10 R201 D203 HVCC Q1 U201 Q4 IC1 ADIM SLPR ENA RS19 RS27 RS21 RS24 RS20 RS28 CS17 RS22 RS18 RS17 RS15 RS14 R126 RS12 FB VMIN REF PG Fault GND FB4 OUT4 CH4 FB3 OUT3 CH3 FB2 OUT2 CH2 CS9 PWM1 C116 SG RS32 CS13 RS25 RS31 CS11 RS23 RS30 CS10 RS16 FLS-XS Series Q3 VDD PWM2 CS CS8 PWM3 R127 RS13 FO C125 Q2 CMP C114 PWM4 C127 D204 RS29 PC101 R202 VCTR FB1 AR OUT1 C126 CH1 R134 VCC R135 C205 OVR R136 C206 CS7 R203 C204 C124 RT RS11 D107 PC101 CS14 CS15 CS12 CS16 Figure 33. LED Lighting Driver © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 16 FAN7346 — 4-Channel LED Current Balance Controller Typical Application Circuit (Lighting) (Continued) FAN7346 — 4-Channel LED Current Balance Controller Typical Application Circuit (Continued) Figure 34. Multiple Controller Driving © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 17 FAN7346 — 4-Channel LED Current Balance Controller Physical Dimensions Figure 35. 28-Lead, Small-Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300-Inch, Wide Body Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 18 FAN7346 — 4-Channel LED Current Balance Controller © 2011 Fairchild Semiconductor Corporation FAN7346 • 1.0.0 www.fairchildsemi.com 19