UNISONIC TECHNOLOGIES CO., LTD UU28141 CMOS IC 1.4A BOOST FOR WHITE LED DRIVER DESCRIPTION The UTC UU28141 is a high frequency, asynchronous boost converter. The internal MOSFET can support up to 8 White LEDs for backlighting and OLED power application, and the internal soft start function can reduce the inrush current. The UTC UU28141 uses current mode, 1.0MHz fixed frequency architecture to regulate the LED current, which is set through an external current sense resistor. Its low 300mV feedback voltage reduces power loss and improves efficiency. The OVP pin monitors the output voltage and turns off the converter if an over-voltage condition is present due to an open circuit condition. The UTC UU28141 includes under-voltage lockout, current limiting and thermal shutdown protection preventing damage in the event of an output overload. FEATURES * 2.5V~5.5V operating input voltage range * Drives up to 8 series White LEDs * 1.0MHz Fixed Switching Frequency * Wide range for PWM dimming (200Hz~200KHz) * Internal 1.4A switching current limit * Over Voltage Protection (OVP) * Internal Soft-start Function * Current limit and Thermal shutdown protection * Under voltage Lockout ORDERING INFORMATION Ordering Number UU28141G-AE6-R Package SOT-23-6 Packing Tape Reel MARKING www.unisonic.com.tw Copyright © 2016 Unisonic Technologies Co., Ltd 1 of 5 QW-R125-040.B UU28141 PIN CONFIGURATION SW 1 6 VCC GND 2 5 OVP FB 3 4 EN PIN DESCRIPTION PIN NO. 1 2 3 4 5 6 CMOS IC PIN NAME SW GND FB EN OVP VCC DESCRIPTION Switching Pin. Ground Pin. Feedback Pin. Chip Enable & Dimming pin. Active high. Internal pull low. Over voltage detect pin. Power Input Pin. BLOCK DIAGRAM VCC UVLO and POR SW REFERENCE SOFTSTART and BIAS Thermal Shutdown ILIMIT Current Sense + + EA - LPF FB - COMP PWM CONTROL LOGIC OVP OVP + Shutdown DRIVER Enable Logic 10ms EN OSCILLATOR UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw GND 2 of 5 QW-R125-040.B UU28141 CMOS IC ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT VCC Pin Voltage VIN -0.3 ~ 6 V SW Pin Voltage VSW -0.3 ~ 33 V OVP Pin Voltage VOVP -0.3 ~ 33 V EN, FB Pins Voltage -0.3 ~ VIN+0.3 V Operating Junction Temperature TOPR -40 ~ +125 °C Storage Temperature Range TSTG -65 ~ +150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. RECOMMENDED OPERATING CONDITIONS PARAMETER Input Supply Voltage Ambient Temperature SYMBOL VIN TA RATINGS 2.5 ~ 5.5 -40 ~ +125 UNIT V °C THERMAL CHARACTERISTICS PARAMETER SYMBOL RATINGS UNIT Junction To Ambient θJA 250 °C/W Junction to Case θJC 180 °C/W Note: θJA is measured with the PCB copper are (need connect to GND of the UTC UU28141) of approximately 1 in2 (Multi-layer). ELECTRICAL CHARACTERISTICS (VIN=5V, VEN=5V, IOUT=20mA, TA=25°C) PARAMETER Input Voltage Range Input UVLO UVLO Hysteresis OVP Sense Voltage Quiescent Current Supply Current Shutdown Current FB Pin Voltage FB Pin Current Load Regulation Line Regulation EN Pin Voltage High EN Pin Voltage Low EN Hysteresis EN Pin Sink Current Switching Frequency N-Channel MOSFET Current Limit (Note) Switching Maximum Duty Dimming Clock Rate N-Switch RDS (ON) Thermal Shutdown Thermal Shutdown Protection Hysteresis Note: Guaranteed by design. SYMBOL TEST CONDITIONS VIN UVLO Rising VOV ICCQ IIN ISD VFB IFB 27.5 VFB=0.5V, IOUT=0mA VFB=0V, Switching VEN=0V, TEN>20mS 0.285 1mA<IOUT<20mA 3V<VIN<4.3V VENH VENL IIH FOSC CL CL DMAX TYP MAX 5.5 2.45 2.25 0.1 29 200 400 1 2 1 4 0.300 0.315 ±100 1 1 1.4 0.4 0.75 Duty on 50% 0.1 1 1 1.4 1.9 92 0.2 RDS(ON)-N VIN=3.6V TSD TSH UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN 2.5 0.5 155 25 1.25 200 1.0 UNIT V V V V μA mA μA V nA % % V V V μA MHz A A % KHz Ω °C °C 3 of 5 QW-R125-040.B UU28141 CMOS IC FUNCTION DESCRIPTION Setting the ILED Current Application circuit item shows the basic application circuit with UTC UU28141 adjustable output version. The external resistor sets the LED output current according to the following equation: ILED 20mA 350mA REST 15Ω 0.857Ω 6mW 105mW Under Voltage Lockout (UVLO) To avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the device, if the input voltage falls below (2.25V~100mV). Over Voltage Protection OVP measure the output voltage for open circuit protection. Connect OVP pin to the output at the top of the LED string. If VOUT above 36V, the OVP protection is happened that stops the internal driver until VOUT below 36V. Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 2.2uf ceramic capacitor for most applications is sufficient. For a lower output power requirement application, this value can be decreased. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. A 1uF ceramic capacitors works for most of the applications. Higher capacitor values can be used to improve the load transient response. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 5 QW-R125-040.B UU28141 CMOS IC TYPICAL APPLICATION CIRCUIT UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 5 QW-R125-040.B