FSP3604

3W HIGH POWER WHITE LED DRIVER FSP3604 FEATURES LED Power Efficiency: up to 90% 1MHz Switching Frequency Uses small, Low Profile External Components Low Start-Up Voltage: 0.9V(ILED =270mA) Low RDS(ON) : 100mΩ (TYP.) Open LED Protection Over Temperature Protection Low Profile SOT23-6L Package GENERAL DESCRIPTION The FSP3604 is a step up DC-DC converter that delivers a regulated output current. The device switches at a 1.0MHz constant frequency, allowing for the use of small value external inductor and ceramic capacitors. The FSP3604 is targeted to be used for driving loads up to 1A from a two-cell alkaline battery. The LED current can be programmed by the external current sense resistor, Rs, connected between the feedback pin (FB) and ground. A low 95mV feedback voltage reduces the power loss in the Rs for better efficiency. With its internal 2A, 100mΩ NMOS switch, the device can provide high efficiency even at heavy load. During the shutdown mode, the feedback resistor Rs and the load are completely disconnected and the current consumption is reduced to less than 1uA. APPLICATIONS White LED Torch (Flashlight) White LED Camera Flash DSC (Digital Still Camera)Flash Cellular Camera Phone Flash PDA Camera Flash Camcorder Torch (Flashlight) Lamp PIN CONFIGURATION (Top View) VIN VOUT SHDN 6 5 4 1 SW 2 GND 3 FB Pin Number 1 2 3 4 5 6 Pin Name SW GND FB SHDN VOUT VIN Pin Function Power Switch Pin. Ground Pin Feedback Pin Chip Shutdown Signal Input Power Output Pin. Power Supply Input. TYPICAL APPLICATION CIRCUIT 1/6 2007-7-13 3W HIGH POWER WHITE LED DRIVER ABSOLUTE MAXIMUM RATINGS(NOTE 1) Parameter VIN Rating FSP3604 Unit V - 0.3 ~ +6 VSW - 0.3 ~ +6 A FB SHDN Voltages - 0.3 ~ +6 ℃ Operating Temperature Range - 40 ~ +85 ℃ Operating Junction Temperature -40~+125 ℃ Lead Temperature (Soldering 5 sec.) + 300 ℃ Internal Power Dissipation 400 mW 250(θJA) Thermal Resistance ℃/W 130(θJC) Storage Temperature Range - 65 ~ +125 ℃ Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. ELECTRICAL CHARACTERISTICS (VIN= 2.4V, ILED=750mA, VSHDN=VIN, L=2.2uH, CIN=10uF, CO=10uF, TA=25℃, Unless otherwise noted) Parameter Condition Min. Typ. Max. Input Voltage Range Start-Up Voltage Hold Voltage Switching Frequency SHDN Input High SHDN Input Low Feedback Voltage Over Temperature Shutdown Over Temperature Hysteresis Maximum Output Current Range Quiescent Current Shutdown current Switch on Resistance Current Limit Efficiency Note 2: VF: LED Forward Voltage ILED = 0mA, VO = 3.4V Device Switching at 1MHz Shutdown mode VO = 3.4V VO = 3.4V ILED = 750mA 2 90 1 0.1 3 1 mA uA Ω A % 750 VIN = 1.8V VIN = 1.8V 90 95 150 15 VIN: 0V→2.4V, ILED = 100mA VIN: 2.4V→0V, ILED : 750mA→200mA 0.85 1.0 0.4 100 0.9 0.7 0.75 1.0 1.15 VF-0.2 (Note 2) 0.9 Unit V V V MHz V mV ℃ ℃ mA 2/6 2007-7-13 3W HIGH POWER WHITE LED DRIVER FUNCTIONAL BLOCK DIAGRAM FSP3604 APPLICATION INFORMATION Inductor Selection The FSP3604 can use small value inductors due to its switching frequency of 1 MHz. The value of inductor will focus in the range of 2.2uH to 4.7uH for most FSP3604 applications. In typical high current white LED applications, it is recommended to use a 4.7uH inductor. The inductor should have low DCR (DC resistance) to minimize the I2 R power loss, and it requires a current rating of 2A to handle the peak inductor current without saturating. Capacitor Selection An input capacitor is required to reduce the input ripple and noise for proper operation of the FSP3604. For good input decoupling, Low ESR (equivalent series resistance) capacitors should be used at the input. At least 2.2uF input capacitor is recommended for most applications. A minimum output capacitor value of 6.8uF is recommended under normal operating conditions, while a 10uF-22uF capacitor may be required for higher power LED current. A reasonable value of the output capacitor depends on the LED current. The ESR of the output capacitor is the important parameter to determine the output voltage ripple of the converter, so low ESR capacitors should be used at the output to reduce the output voltage ripple. The small size of ceramic capacitors is an excellent choice for FSP3604 applications. The X5R and X7R types are preferred because they maintain capacitance over wide voltage and temperature ranges. Diode Selection It's indispensable to use a Schottky diode rated at 2A with the FSP3604. Using a Schottky diode with a lower forward voltage drop is better to improve the power LED efficiency, and its voltage rating should be greater than the output voltage. In application, the ON semiconductor MBRA210LT3G is recommended. LED Current Setting The LED current is set by the single external Rs resistor connected to the FB pin as shown in the typical application circuit on page 1. The typical FB reference is internally regulated to 95mV. The LED current is 95mV/Rs. It's recommended to use a 1% or better precision resistor for the better LED current accuracy. The formula and table 1 for Rs selection are shown as follows: Rs=95mV/I Table 1. Rs Resistor Value Selection 3/6 2007-7-13 3W HIGH POWER WHITE LED DRIVER PCB Layout Guidelines As for all switching power supplies, the layout and components placement of the FSP3604 is an important step in the design; especially at high peak currents and high switching frequencies. The input capacitor and output capacitor should be placed respectively as close as possible to the input pin and output pin of the IC; the inductor and schottky diode should be placed as close as possible to the switch pin by using wide and short traces for the main current path; the current sense resistor should be placed as close as possible between the ground pin and feedback pin. FSP3604 TYPICAL CHARACTERISCITS (L=2.2uH, CIN=10uF, CO=10uF, TA=25℃, Unless otherwise noted) 4/6 2007-7-13 3W HIGH POWER WHITE LED DRIVER TYPICAL CHARACTERISCITS (CONTINUED) (L=2.2uH, CIN=10uF, CO=10uF, TA=25℃, Unless otherwise noted) FSP3604 ORDERING INFORMATION FSP3604XXX Package: C: SOT23-6L Packing: A: Tape & Reel Temperature Grade: D: -40~85℃ MARKING INFORMATION XXVYW Date code: Y: Year (1=2001) W: Week (A~Z, a~z) Voltage Code Product Code 5/6 2007-7-13 3W HIGH POWER WHITE LED DRIVER FSP3604 PACKAGE INFORMATION D e1 6 5 4 E1 E A2 A e b C θ L Symbol A A1 A2 b C D E E1 L e e1 θ Dimensions In Millimeters Min. Max. 0.900 1.450 0.000 0.150 0.900 1.300 0.300 0.500 0.100 0.200 2.800 3.100 2.50 3.100 1.500 1.700 0.200 0.550 0.95 Bsc. 1.90 Bsc. 0ο 8ο A1 1 2 3 Dimensions In Inches Min. Max. 0.036 0.058 0.000 0.006 0.036 0.052 0.012 0.020 0.004 0.008 0.112 0.124 0.100 0.124 0.060 0.068 0.002 0.022 0.038 Bsc. 0.076 Bsc. 0ο 8ο 6/6 2007-7-13