IS31LT3505

IS31LT3505 1.0MHZ BOOST CONVERTER WITH 35V INTERNAL NMOS OCTOBER 2011 DESCRIPTION The IS31LT3505 is a constant current step-up converter with internal NMOS. The step-up converter topology allows series connection of the white LEDs so the LED currents are identical for uniform brightness as well as constant output voltage to drive other devices. The output current of each channel can be set by an external resistor and dimming the brightness of LEDs with the PWM signal or DC voltage. The IS31LT3505 operates with a switching frequency up to 1 MHz. A low 0.3V feedback voltage minimizes power loss in the current setting resistor for better efficiency. With OVP circuit, the chip and the system can be safe even if the load is not connected. IS31LT3505 is available in MSOP-10. It operates from 6V to 30V over the temperature range of -40°C to +85°C. FEATURES  6V to 30V supply voltage  High efficiency: 90 % typical  PWM dimming control  Fast 1.0MHz switching frequency  Internal high power 35V NMOS  Internal soft start  Adjustable LED Open Protection  Over-temperature protection  MSOP-10 APPLICATIONS  TV monitor backlighting  PDA, handheld computer  GPS receiver TYPICAL APPLICATION CIRCUIT L1 10μ H 300Ω 100kΩ D1 (Schottky,ss26) 6.0V~30V 4 9 EN VDD LX OVP VP 10 http://www.DataSheet4U.net/ R1 6 2 C3 1 μF R2 C OUT 22μ F C IN 22μ F C1 1μF IS31LT3505 C2 1μF 10nF 10 μF 1, 3, 5 GND FB 7 R SE T Figure 1 Application Circuit (Constant Current to Drive White LEDs)    ...