LT3466 Dual Full Function White LED Step-Up Converter with Built-In Schottky Diodes FEATURES DESCRIPTIO Drives Up to 20 White LEDs (10 in Series LT 3466 is a dual full function step-up DC/DC converter per Converter) from a 3.6V Supply specifically designed to drive up to 20 White LEDs (10 in Two Independent Step-Up Converters Capable of series per converter) with a constant current. Series Driving Asymmetric LED Strings connection of the LEDs provides identical LED currents Independent Dimming and Shutdown Control resulting in uniform brightness and eliminating the need of the Two LED Strings for ballast resistors and expensive factory calibration. Internal Schottky Diodes The two independent converters are capable of driving Internal Soft-Start Eliminates Inrush Current asymmetric LED strings. The dimming of the two LED Open LED Protection (39.5V Max V ) OUT strings can also be controlled independently. The LT3466 Fixed Frequency Operation Up to 2MHz is ideal for providing backlight for main and sub-displays 81% Efficiency Driving 16 White LEDs at 15mA in cell phones and other handheld devices. (Eight per Driver) from a 3.6V Supply The LT3466 operating frequency can be set with an Wide Input Voltage Range: 2.7V to 24V external resistor over a 200kHz to 2MHz range. A low Available in 10-Pin DFN and 16-Pin Thermally 200mV feedback voltage minimizes power loss in the Enhanced TSSOP Packages current setting resistor for better efficiency. Additional U APPLICATIO S features include output voltage limiting when LEDs are disconnected and internal soft-start. Main/Sub Displays The LT3466 is available in the 10-pin (3mm 3mm Digital Cameras, Sub-Notebook PCs 0.75mm) DFN and 16-pin thermally enhanced TSSOP PDAs, Handheld Computers packages. Automotive , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO 3V TO 5V Conversion Efficiency 85 1F V = 3.6V IN 8/8 LEDs 80 L1 L2 47H 47H 75 SW1 V SW2 IN 70 LED1 LED2 V V OUT1 OUT2 2.2F 2.2F 65 LT3466 FB1 FB2 60 R CTRL1 T GND CTRL2 55 63.4k OFF ON OFF ON 10 10 50 10 SHUTDOWN SHUTDOWN 0 5 15 20 AND DIMMING AND DIMMING 3466 F01a LED CURRENT (mA) CONTROL 1 CONTROL 2 3466 F01b Figure 1. Li-Ion Powered Driver for 8/8 White LEDs 3466fa 1 EFFICIENCY (%) U ULT3466 ABSOLUTE AXI U RATI GS (Note 1) Input Voltage (V ) ................................................... 24V Maximum Junction Temperature ......................... 125C IN SW1, SW2 Voltages ................................................ 44V Storage Temperature Range V , V Voltages ............................................. 44V DFN .................................................. 65C to 125C OUT1 OUT2 CTRL1, CTRL2 Voltages ........................................... 24V TSSOP .............................................. 65C to 150C FB1, FB2, R Voltages ................................................ 2V Lead Temperature (Soldering, 10 sec, TSSOP) ..... 300C T Operating Temperature Range (Note 2) ... 40C to 85C UUW PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART ORDER PART NUMBER NUMBER GND 1 16 GND TOP VIEW NC 2 15 FB1 LT3466EDD LT3466EFE V 1 10 FB1 OUT1 V 3 14 CTRL1 OUT1 SW1 2 9 CTRL1 4 SW1 13 NC V 3 11 8 R 17 IN T 5 V 12 R IN T SW2 4 7 CTRL2 6 SW2 11 CTRL2 V 5 6 FB2 OUT2 7 V 10 FB2 OUT2 DD PART MARKING FE PART MARKING DD PACKAGE 8 GND 9 GND 10-LEAD (3mm 3mm) PLASTIC DFN LBBH 3466EFE T = 125C, = 43C/W, = 2.96C/W FE PACKAGE JMAX JA JC 16-LEAD PLASTIC TSSOP EXPOSED PAD (PIN 11) IS GND MUST BE SOLDERED TO PCB T = 125C, = 38C/W, = 10C/W JMAX JA JC(PAD) EXPOSED PAD (PIN 17) IS GND MUST BE SOLDERED TO PCB Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes specifications that apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 3V, V = 3V, V = 3V, unless otherwise specified. A IN CTRL1 CTRL2 PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage 2.7 V Maximum Operating Voltage 24 V FB1 Voltage 192 200 208 mV FB2 Voltage 192 200 208 mV Offset Voltage (V ) Between FB1 and FB2 Voltages V = FB1 FB2 0 1.5 7.5 mV OS OS FB1 Pin Bias Current V = 0.2V (Note 3) 10 50 nA FB1 FB2 Pin Bias Current V = 0.2V (Note 3) 10 50 nA FB2 Quiescent Current V = V = 0.3V 5 7.5 mA FB1 FB2 CTRL1 = CTRL2 = 0V 16 25 A Switching Frequency R = 48.7k 0.8 1 1.2 MHz T Oscillator Frequency Range (Note 4) 200 2000 kHz Nominal R Pin Voltage R = 48.7k 0.54 V T T Maximum Duty Cycle R = 48.7k 90 96 % T R = 20.5k 92 % T R = 267k 99 % T 3466fa 2 U WWW