FAN5340 Synchronous Constant-Current Series Boost LED Driver with PWM Brightness Control and Integrated Load Disconnect Features Description The FAN5340 is a synchronous constant-current LED driver capable of efficiently delivering up to 500mW to a string of up to four LEDs in series. Optimized for small form-factor applications, the 1.2MHz fixed switching frequency allows the use of chip inductors and capacitors. Synchronous Current-Mode Boost Converter Up to 500mW Output Power Supports 2, 3, or 4 LEDs in Series 2.7V to 4.8V Input Voltage Range 1.2MHz Fixed Switching Frequency 1mA Maximum Quiescent Current Soft-Start Capability Input Under-Voltage Lockout (UVLO) Output Over-Voltage Protection (OVP) Short-Circuit Detection Thermal Shutdown (TSD) Protection For safety, the device features integrated short-circuit detection plus over-voltage and thermal shutdown protections. In addition, input under-voltage lockout protection is triggered if the battery voltage is low. Brightness (dimming) control is implemented by applying a PWM signal of 300Hz to 1kHz on the EN pin. During shutdown, the FAN5340 disconnects the LED anodes from the output of the boost regulator, which holds the boost regulator’s voltage on COUT, reducing audible noise from the PWM dimming and removing power from the LED string. 8-Lead 3.00 x 3.00mm MLP 8-Bump 1.57 x 1.57mm WLCSP GND Applications Cellular Phones, Smart Phones Pocket PCs WLAN DC-DC Converter Modules PDA, DSC, PMP, and MP3 Players EN VLED FB 8 2 7 3 P1 GND 6 4 5 VIN VOUT COUT CIN L1 2–4 LEDs 1 SW PGND RSET Figure 1. Typical Application Ordering Information Part Number Operating Temperature Range FAN5340UCX -40 to 85°C 8-Bump, 1.57 x 1.57mm Wafer Level Chip-Scale Package (WLCSP) Tape and Reel FAN5340MPX (Prelminary) -40 to 85°C 8-Lead, 3.00 x 3.00mm Molded Leadless Package (MLP) Tape and Reel © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 Package Packing www.fairchildsemi.com FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control April 2010 L1 SW VIN Q1 Q2 D1 CIN GATE DRIVE VOUT PGND COUT Q3 VLED BOOST CONTROL 2–4 LEDs EN GND FB RSET Figure 2. Table 1. 15 133Ω Block Diagram Recommended External Components Component Description Vendor Parameter (1) Min. Typ. Max. Units 22 μH 4.7μF X5R or Better DCR (Series R) C 1100 4.7 mΩ μF 4.7μF X5R or Better C 4.7 μF L1 22μH Nominal COUT CIN Murata LQH3NPN220MGOK L Note: 1. Minimum L (inductance) incorporates tolerance, temperature, and DC bias effects (L decreases with increasing current). © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 2 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Block Diagrams GND EN VLED A1 A2 A3 A3 VIN B1 B3 A2 FB B3 C1 C2 C3 VOUT SW PGND C3 Figure 3. A1 WLCSP Package, Top View GND 1 EN 2 VLED 3 FB 4 Figure 5. Figure 4. P1 GND 8 VIN 7 VOUT 6 SW 5 PGND B1 C2 C1 WLCSP Package, Bottom View 8-Pin 3 x 3mm MLP, Top View Pin Definitions Pin # Name Description CSP MLP A1 1 GND A2 2 EN A3 3 VLED B3 4 FB C3 5 PGND C2 6 SW Switching Node. Tie inductor L1 from VIN to this pin. C1 7 VOUT Boost Output Voltage. Output of the boost regulator. B1 8 VIN © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 Analog Ground. All signals are referenced to this pin. Enable / PWM Brightness Control. A logic LOW on this pin shuts down the IC, disconnects the LEDs from VOUT, and reduces the current consumption of the IC. This terminal has an internal pull-down resistor of 300kΩ. LED String Output. Connected to the anode of a series string of two to four LEDs. Current Feedback. The boost regulator regulates this pin to 0.5V to control the LED string current. Tie this pin via a current-setting resistor (RSET) to GND and the cathode of the LED string. Power Ground. The boost switch and gate drivers are grounded at this pin. Input Voltage. www.fairchildsemi.com 3 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control 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 Min. Max. Units VIN –0.3 6.0 V FB, EN Pins –0.3 VIN + 0.3 V VSW SW Pin –0.3 24.0 V VOUT VOUT Pin 24.0 V VIN VFB, VEN ESD Parameter –0.3 Electrostatic Discharge Protection Level Human Body Model per JESD22-A114 4.0 Charged Device Model per JESD22-C101 1.5 kV TJ Junction Temperature –40 +150 °C TSTG Storage Temperature –65 +150 °C +260 °C TL Lead Soldering Temperature, 10 Seconds Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to absolute maximum ratings. Symbol VIN Parameter Min. Typ. Max. Units V VIN Supply Voltage 2.7 4.8 VOUT VOUT Voltage 6.2 16.0 V IOUT VOUT Load Current 5 40 mA 1000 Hz fEN_PWM EN pin PWM Dimming Frequency 100 300 TA Ambient Temperature –40 +85 °C TJ Junction Temperature –40 +125 °C Thermal Properties Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer 2s2p evaluation boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction temperature TJ(max) at a given ambient temperate TA. Symbol θJA Parameter Junction-to-Ambient Thermal Resistance © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 Typ. Units WLCSP Package 110 °C/W MLP Package 49 °C/W www.fairchildsemi.com 4 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Absolute Maximum Ratings VIN = 2.7V to 4.8V and TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = 25°C and VIN = 3.6V. Symbol Parameter Conditions Min. Typ. Max. Units 1 mA 0.3 1.0 μA Power Supplies IQ Quiescent Current EN = VIN, Device Not Switching ISD Shutdown Supply Current EN = GND, VIN = 3.6V VUVLO VUVHYST Under-Voltage Lockout VIN Rising 2.30 2.40 2.50 V VIN Falling 2.00 2.15 2.25 V Under-Voltage Lockout Hysteresis 250 mV EN: Enable Pin VIH HIGH-Level Input Voltage 1.2 VIL LOW-Level Input Voltage REN EN Pull-Down Resistance tSD EN Low to Shutdown Delay V 0.4 V 400 kΩ 80 ms 500 520 mV VFB = 500mV 0.1 1.0 μA VIN = 3.6V, VOUT = 10V, ISW = 100mA 600 VIN = 2.7V, VOUT = 10V, ISW = 100mA 850 RDS(ON)_Q2 Synchronous Rectifier On-Resistance VOUT = 10V, ISW = 100mA 2.0 Ω RDS(ON)_Q3 Load Switch On-Resistance VOUT = 10V, ILED = 10mA 2.8 Ω SW Node Leakage EN = 0, VIN = VSW = VOUT = 5.5V, VLED = 0 0.1 1.0 μA Boost Switch Peak Current Limit VIN = 3.6V 325 400 475 mA 1.0 1.2 1.4 MHz 100 % 20.0 V 200 From Falling Edge of EN 300 20 Feedback and Reference VFB Feedback Voltage 480 IFB Feedback Input Current Power Outputs RDS(ON)_Q1 Boost Switch On-Resistance ISW(OFF) ILIM-PK (2) mΩ Oscillator fSW Boost Regulator Switching Frequency PWM Dimming DPWM (3) PWM Duty Cycle PWM Dimming Frequency ≤1kHz 1.0 Output and Protection VOVP VOVPHYST VTHSC DMAX Boost Output Over-Voltage Protection 18.0 OVP Hysteresis VLED Short-Circuit Detection Threshold Maximum Boost Duty Cycle 19.0 0.8 V VOUT Falling VIN – 1.5 V VOUT Rising VIN – 1.3 V (3) 85 % (3) DMIN Minimum Boost Duty Cycle TSD Thermal Shutdown 150 20 °C % THYS Thermal Shutdown Hysteresis 25 °C Notes: 2. SW leakage current includes the leakage current of three internal switches; SW to GND, VOUT to VLED, and SW to VOUT. 3. Guaranteed by design. © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 5 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Electrical Specifications VIN = 3.6V, TA = 25°C, ILED = 20mA, L = 22µH, COUT = 4.7µF. Figure 6. Efficiency vs. LED Current: Two LEDs Figure 8. Efficiency vs. LED Current: Four LEDs Figure 10. Figure 7. FB Voltage vs. Input Voltage vs. Temperature © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 Efficiency vs. LED Current: Three LEDs Figure 9. fSW vs. Input Voltage vs.Temperature Figure 11. OVP vs. Input Voltage vs. Temperature www.fairchildsemi.com 6 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Typical Characteristics Figure 12. PWM Linearity Over Full Dimming Duty Cycle Range, Four LEDs Figure 14. Figure 16. Figure 13. Figure 15. Maximum Output Current at VOUT PWM Linearity with Dimming Duty Cycle <2.5%, Four LEDs Line Transient with 10µs Line Step, Four LEDs Over-Voltage Protection: Soft-Start into Open LED String © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 7 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Typical Characteristics (Continued) Figure 17. Cold-Start Waveform with 100% Duty Cycle at 1ms/Div. Figure 18. Cold-Start Waveform with 100% Duty Cycle Showing Startup, Shutdown and Startup at 10ms/Div Figure 19. FAN5340 ILOAD Step from 20mA to 30mA by Enabling FAN5640 at 10mA, Three LEDs © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 Figure 20. FAN5340 ILOAD Step from 30mA to 20mA by Disabling FAN5640 at 10mA, Three LEDs www.fairchildsemi.com 8 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Typical Characteristics (Continued) Overview Over-Voltage Protection The FAN5340 is an inductive current-mode boost serial LED driver that achieves LED current regulation by maintaining 0.5V across RSET. The current through the LED string (ILED) is therefore: If the LED string is open circuit, FB remains at 0V and the output voltage continues to increase in the absence of an Over-Voltage Protection (OVP) circuit. The FAN5340’s OVP circuit disables the boost regulator when VOUT exceeds 19.0V and continues to keep the regulator off until VOUT drops below 18.2V. I LED = 0 .5 RSET (1) Thermal Shutdown While the forward-voltage across the LEDs determines VOUT, the FAN5340’s boost regulator output can also support additional loads on VOUT (see Figure 21) provided its input current limit is not exceeded. If the die temperature exceeds 150°C, a reset occurs and remains in effect until the die cools to 125°C, at which time the circuit is allowed to begin the soft-start sequence. Applications Using VOUT to Drive Additional LED Strings The VOUT pin can be used as a supply for simple current sources (shown in Figure 22 using the FAN5640) or discrete current sinks. To avoid dragging VOUT down when the EN pin is LOW, the auxiliary strings should not be enabled unless the EN pin is HIGH. The auxiliary strings can therefore be PWM dimmed using either the same line as the EN line as shown below or enabled separately, but within the on-time of the FAN5340. IOUT1 1 GND R1 Figure 21. 2 RSET GND If EN has been LOW for more than 20ms, the IC initiates a “cold start” soft-start cycle when EN rises, provided VIN is above the UVLO threshold. The soft-start circuit ramps the voltage reference to the error amplifier to control inrush current. VLED FB 5 4 1 8 2 7 3 4 FAN5340 6 5 IOUT2 VIN EN VIN VOUT COUT CIN L1 EN FAN5640 3 Maximum Output Current vs. Input Voltage UVLO and Soft-Start 6 SW PGND R2 PWM Dimming When EN goes LOW, the IC turns off a MOSFET (Q3 in Figure 2), which disconnects the LED load, preventing COUT from being discharged when EN is LOW. As long as EN is low for less than 20ms, the regulator’s main regulation loop quickly regains control when EN returns to a HIGH state. Figure 22. Driving Additional LED Strings If using VOUT to drive additional loads, care should be taken not to exceed the input current limit. This limitation is shown in Figure 21 for a typical IC. The total load (IOUT1 + IOUT2 + ILED) should always remain below 70% of the value in Figure 21. Short-Circuit Detection If VOUT falls below VIN – 1.5V, Q3 turns off and remains off until VOUT recovers to at least VIN – 1.3V. © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 9 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Circuit Description Product-Specific Dimensions Product D E X Y FAN5340UC 1.570 1.570 0.285 0.285 Figure 23. 8-Bump, 1.57 x 1.57mm Wafer Level Chip-Scale Package (WLCSP) 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/. © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 10 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Physical Dimensions FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control Physical Dimensions (Continued) Figure 24. 8-Pin, 3 x 3mm Molded Leadless Package (MLP) 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/. © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1 www.fairchildsemi.com 11 FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control 12 www.fairchildsemi.com © 2010 Fairchild Semiconductor Corporation FAN5340 • Rev. 1.0.1