FAN5341 Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Features Description The FAN5341 is an asynchronous constant-current LED driver capable of efficiently delivering up to 500mW to a string of up to five LEDs in series. Optimized for small formfactor applications, the 1.2MHz fixed switching frequency allows the use of small chip inductors and capacitors. Asynchronous Boost Converter Internal Schottky Diode Up to 500mW Output Power Drives 3 to 5 LEDs in Series The FAN5341 uses a simple single-wire digital control interface to program the brightness levels of the LEDs in 32 linear steps by applying digital pulses. 2.7V to 5.5V Input Voltage Range Single-Wire Digital Control Interface to Set LED Brightness Levels For safety, the device features integrated over-voltage, overcurrent, short-circuit detection, and thermal-shutdown protection. In addition, input under-voltage lockout protection is triggered if the battery voltage is too low. − 32 Linear Steps 1.2MHz Fixed Switching Frequency Soft-Start Capability The FAN5341 is available in a very low profile, small formfactor 2mm x 2mm x 0.55mm 6-lead UMLP package that is green and RoHS compliant. Input Under-Voltage Lockout (UVLO) Output Over-Voltage Protection (OVP) Short-Circuit Detection Thermal Shutdown (TSD) Protection Low Profile 6-lead 2.0 x 2.0 x 0.55mm UMLP Package Applications Cellular Mobile Handsets Mobile Internet Devices Portable Media Players PDA, DSC, MP3 Players Ordering Information Part Number Temperature Range FAN5341UMPX -40 to 85°C Eco Status Green Package Packing 6-lead, 2.0 x 2.0mm UMLP Tape and Reel For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface November 2009 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Typical Application Diagram Figure 1. Typical Application Block Diagram Figure 2. Functional Block Diagram © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 2 VOUT 1 VIN 2 EN 3 P1 GND 6 GND 5 SW 4 FB Figure 3. UMLP6 Package, ^Top View Pin Definitions Pin # Name Description 1 VOUT Boost Output Voltage. Output of the boost regulator. Connect the LEDs to this pin. Connect COUT (Output Capacitor) to GND. 2 VIN Input Voltage. Connect to power source and decouple with CIN to GND. 3 EN Enable Brightness Control. Program dimming levels by driving pin with digital pulses. 4 FB Voltage Feedback. The boost regulator regulates this pin to 0.253V to control the LED string current. Tie this pin to a current setting resistor (RSET) between GND and the cathode of the LED string. 5 SW Switching node. Tie inductor L1 from VIN to SW pin. 6 GND Ground. Tie directly to a GND plane. © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 3 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface 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. Units VIN -0.3 6.0 V FB, EN Pins -0.3 VIN + 0.3 V VSW SW Pin -0.3 22.0 V VOUT VOUT Pin –0.3 22.0 V ESD Electrostatic Discharge Protection Human Body Model per JESD22-A114 Level Charged Device Model per JESD22-C101 VIN VFB, VEN 3.3 kV 2.0 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 Comments VIN Supply Voltage (1) VOUT VOUT Voltage IOUT VOUT Load Current Max. Units 2.7 5.5 V 6.2 17.5 V 5 25 mA TA Ambient Temperature -40 +85 °C TJ Note: Junction Temperature -40 +125 °C 1. 500mW Maximum Output Power Min. Application should guarantee that minimum and maximum duty-cycle should fall between 20-85% to meet the specified range Thermal Properties Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer 2s2p boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction temperature TJ(max) at a given ambient temperature TA. Symbol Parameter θJA Junction-to-Ambient Thermal Resistance, UMLP6 Package © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 Typical Units 70 °C/W www.fairchildsemi.com 4 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Absolute Maximum Ratings VIN = 2.7V to 5.5V 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 0.30 0.75 μA 2.35 2.15 2.60 2.40 V Power Supplies ISD Shutdown Supply Current EN = GND, VIN = 3.6V VUVLO Under-Voltage Lockout Threshold VIN Rising VIN Falling VUVHYST Under-Voltage Lockout Hysteresis 2.10 1.90 250 mV EN: Enable Pin VIH HIGH-Level Input Voltage VIL LOW-Level Input Voltage 1.2 200 V 300 0.4 V 400 kΩ 300 µs REN EN Pull-Down Resistance TLO EN Low Time for Dimming VIN = 3.6V; See Figure 14 0.5 THI Time Delay Between Steps VIN = 3.6V; See Figure 14 0.5 µs TSD EN Low, Shutdown Pulse Width VIN = 3.6V; from Falling Edge of EN 1 ms Feedback and Reference VFB Feedback Voltage ILED = 20mA from -40°C to +85°C, 2.7V ≤ VIN ≤ 5.5V IFB Feedback Input Current 240 253 266 mV VFB = 253mV 0.1 1.0 μA VIN = 3.6V, ISW = 100mA 600 VIN = 2.7V, ISW = 100mA 650 SW Node Leakage EN = 0, VIN = VSW = VOUT = 5.5V, VLED = 0 0.1 Boost Switch Peak Current Limit VIN = 3.6V 750 Power Outputs RDS(ON)_Q1 ISW(OFF) ILIM-PK Boost Switch On-Resistance (1) mΩ 2.0 μA mA Oscillator fSW Boost Regulator Switching Frequency 1.0 1.2 1.4 18.0 18.9 21.0 MHz Output and Protection VOVP Boost Output Over-Voltage Protection OVP Hysteresis V 0.8 VTLSC VOUT Short Circuit Detection Threshold VOUT Falling VIN – 1.4 V VTHSC VOUT Short Circuit Detection Threshold VOUT Rising VIN – 1.2 V DMAX Maximum Boost Duty Cycle (2,3) 85 (2,3) DMIN Minimum Boost Duty Cycle TTSD THYS Thermal Shutdown Thermal Shutdown Hysteresis 20 150 35 % °C °C Notes: 1. SW leakage current includes the leakage current of 2 internal switches; SW to GND and SW to VOUT. 2. Not tested in production and guaranteed by design. 3. Application should guarantee that minimum and maximum duty cycle should fall between 20-85% to meet the specified range. © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 5 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Electrical Specifications 90 90 5 LEDs L = 10µH COUT = 1.0µF ILED = 25mA 80 Efficiency (%) Efficiency (%) 80 70 VIN=2.7V 60 5 LEDs L = 4.7µH COUT = 1.0µF ILED = 25mA 70 60 VIN=2.8V VIN=3.6V VIN=3.6V VIN=4.2V VIN=4.2V 50 50 5 10 15 20 25 5 10 LED Current (mA) Figure 4. 5 LEDs: Efficiency vs. LED Current vs. Input Voltage 25 0.8 Delta Feedback Voltage (m V) 4 LEDs L = 10µH COUT = 1.0µF ILED = 25mA 80 Efficiency (%) 20 Figure 5. 5 LEDs: Efficiency vs. LED Current vs. Input Voltage 90 70 VIN=2.7V 60 VIN=3.6V VIN=4.2V 50 0.6 0.4 0.2 0 -0.2 -40°C +25°C -0.4 +85°C -0.6 5 10 15 20 25 2.7 3 LED Current (mA) 3.6 3.9 4.2 Figure 7. Delta of VFB Over Input Voltage and Temperature for 4 LEDs with L=10µH and COUT=1.0µF at ILED=25mA 90 20.0 3 LEDs L = 10µH COUT = 1.0µF ILED = 25mA 80 3.3 Input Voltage (V) Figure 6. 4 LEDs: Efficiency vs. LED Current vs. Input Voltage 4 LEDs L = 10µH COUT = 1.0µF ILED = 25mA 19.5 19.0 OVP (V) Efficiency (%) 15 LED Current (mA) 70 18.5 18.0 60 VIN=2.8V 17.5 VIN=3.6V VIN=4.2V 17.0 50 5 10 15 20 2.7 25 Figure 8. 3 LEDs: Efficiency vs. LED Current vs. Input Voltage © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 3 3.3 3.6 3.9 4.2 Input Voltage (V) LED Current (mA) Figure 9. Over-Voltage Protection vs. Input Voltage www.fairchildsemi.com 6 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Electrical Specifications Figure 10. Line Transient Response for 4 LEDs at VIN=3.6V ± 0.6V with L=10µH, COUT=1.0µF and ILED=25mA Figure 11. FAN5341 Dimming Operation at VIN=3.6V for 4 LEDs with L=10µH, COUT=1.0µF and ILED=25mA Figure 13.Steady-State Waveform for VOUT, Switch Voltage and Inductor Current for 4 LEDs at VIN=3.6V ± 0.6V with L=10µH, COUT=1.0µF and ILED=25mA Figure 12. Startup Waveform for Switch Voltage, Inductor Current, VFB and EN for 4 LEDs at VIN=3.6V± 0.6V with L=10µH, COUT=1.0µF and ILED=25mA © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 7 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Electrical Specifications FAN5341 does not require the system processor to constantly supply a signal to it to drive the LEDs. Overview The FAN5341 is an inductive current-mode boost serial LED driver that achieves LED current regulation by maintaining 0.253V across the RSET resistor. The current through the LED string (ILED) is therefore given by: I LED = 0.253 RSET Digital Dimming Control The FAN5341 starts driving the LEDs at the maximum brightness level. After startup, the control logic is ready to accept programming pulses to decrease the brightness level by the number of positive edges applied to the EN pin. Figure 14 shows the digital pulse dimming control. (1) The voltage VOUT is determined by the sum of the forward voltages across each LED, plus the voltage across RSET, which is always 253mV. Over-Current and Short-Circuit Detection Driving Five LEDs in Series Over-Voltage / Open-Circuit Protection FAN5341 can drive five LEDs in series but, the forward voltage (VF) of the LED MUST be less than 3.5V such that it remains under the over-voltage specification of 18.9V. If the LED string is an open circuit, FB remains at 0V and the output voltag continues to increase in the absence of an over-voltage protection (OVP) circuit. The FAN5341’s OVP circuit disables the boost regulator when VOUT exceeds 18.9V and continues to keep the regulator off until VOUT drops below 18.1V. The boost regulator employs a cycle-by-cycle peak inductor current limit of ~750mA. UVLO and Soft-Start If EN has been low for more than 1ms, the IC may initiate a “cold start” soft-start cycle when EN rises, provided VIN is above the UVLO threshold. Thermal Shutdown When 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. Digital Interface The FAN5341 implements a single-wire digital interface to program the LED brightness to one of thirty-two (32) levels spaced in linear steps. With this single-wire solution, the Figure 14. Digital Pulse-Dimming Control Diagram © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 8 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Circuit Description Inductor & Output Capacitor Selection # of LEDs Inductor (L) 10.0µH 3, 4, 5 4.7µH Part Number Manufacturer LQH43MN100K03 Murata NLCV32T-100K-PFR TDK VLF3010AT-100MR49-1 TDK LQH43MN4R7K03 Murata NLCV32T-4R7M-PFR TDK LPF2010T-4R7M ABCO Min COUT Part Number Manufacturer 1.00µF CV105X5R105K25AT AVX/Kyocera 1.00µF CV105X5R105K25AT AVX/Kyocera Table 1. Recommended External Components Component Placement and PCB Recomendations Figure 1. Recommended Component Placement PCB Recommendations Input Capacitance In a typical application, the input and output capacitors should be placed as close to the IC as possible; no additional capacitance is needed to ensure proper functionality. However, in a testing environment, where the FAN5341 is typically powered by a power supply with relatively long cables, an additional input capacitor (10µF) may be needed to ensure stable functioning. This capacitor should be placed close to where the power supply cables attach to the FAN5341 evaluation board. © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 The inductor can be connected to VIN with vias through another layer if needed. The feedback pin should be connected back to the IC on a sub-layer. www.fairchildsemi.com 9 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Application Information 0.10 C 2.0 2X A B 1.60 1.50 2.0 6 4 0.27 0.50 0.10 C 2X PIN1 IDENT 1.40 TOP VIEW 0.85 1 0.55 MAX 3 0.65 0.10 C 0.08 C 2.40 0.30 (0.15) RECOMMENDED LAND PATTERN 0.05 0.00 C SEATING PLANE SIDE VIEW NOTES: PIN1 IDENT 6x 1 1.35 1.45 3 0.70 0.80 0.35 0.25 6 4 0.65 0.35 6x 0.25 1.30 0.10 C A B 0.05 C BOTTOM VIEW Figure 15. 6-Lead Molded Leadless Package (UMLP) 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/. © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0 www.fairchildsemi.com 10 FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface Physical Dimensions FAN5341 — Series Boost LED Driver with Integrated Schottky Diode and Single-Wire Digital Interface 11 www.fairchildsemi.com © 2009 Fairchild Semiconductor Corporation FAN5341 • Rev. 1.0.0