YB1521 Datasheet | YOBON TECHNOLOGIES

.. High Power Step-Up DC-DC Converter & WLED Driver Features 2.5V to 5.5V Input Voltage Range Built In Power MOSFET Drive Up to 15V @400m A at 5V Vin Less than 1µA Shutdown Current Up to 94% efficiency Over Voltage Protection@18V UVLO, Thermal Shutdown Internal 1.6A Current Limit 200mv Low Reference Voltage Built In Soft Start PWM Dimming SOT23-5 Package Green Package (Ro HS) Available Description The YB1521 is a step-up DC-DC converter which operating as current source to drive up 45 white LEDs (3S15P) in parallel / series configuration from a 5V system rail. Series connecting of LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The light intensity of these LEDs is proportional to the current passing through them. The YB1521 is a fixed frequency of 1.3MHz, allowing the use of tiny low profile inductors and capacitors to minimize footprint and cost in space consideration applications for cellular phone backlighting or other hand held equipment. The wide input voltage range from 2.5V to 5.5V is idea for portable applications with higher conversion efficiency. To control LED brightness, the LED current can be pulsed by applying a PWM signal with a frequency which is typically 50 KHz to the EN pin. Applications Cellular and Smart Phones Handheld puters and PDAs Small LCD Displays GPS Terminals MP3 Players Digital Still and Video Cameras Electronic Books Typical Application Circuit D1 Schottk Efficiency vs. Input Voltage IOUT =100m A L=10μH = 4.5~5.5V L1 6.8u 90 EFFICIENCY (%) IOUT =180m A 80 4.7u/2 V 4.7u/ 1 V I S 15 strings E O GN F … R1 50 4 4.5 5 INPUT VOLTAGE (V) 5.5 6 Figure 1: Typical Application Circuit Figure 2: Efficiency YB1521 MRev.1.1 .yobon..tw .. High Power Step-Up DC-DC Converter & WLED Driver Pin Configuration Figure 3: Pin...