UNISONIC TECHNOLOGIES CO., LTD UU28121 CMOS IC 1.2MHz, HIGH VOLTAGE, BOOST CONVERTER DESCRIPTION The UTC UU28121 is a current mode step up converter intended for small, low power applications. The converter input voltage ranging from 2.5V to 5.5V. The Output voltage can be set up to 28V. The frequency is 1.2MHz allows the use of small external inductors and capacitors and provides fast transient response. Internal soft start results in small inrush current and extends battery life. Internal power MOSFET with very low RDS (ON) provides high efficiency. The UTC UU28121 automatically transits from PWM to PFM during light load condition further increasing efficiency. The converter also provides protection functions such as under-voltage lockout, current limit and thermal shutdown. FEATURES * 2.5V~5.5V operating input voltage range * 1.2MHz Fixed Switching Frequency * Adjustable output voltage range up to 28V * Internal 1.2A switching current limit * Internal Soft-start Function * Current limit and Thermal shutdown protection * Under voltage Lockout ORDERING INFORMATION Ordering Number UU28121G-AF5-R Package SOT-25 Packing Tape Reel MARKING www.unisonic.com.tw Copyright © 2016 Unisonic Technologies Co., Ltd 1 of 6 QW-R135-001.C UU28121 PIN CONFIGURATION VCC EN 5 4 1 2 3 SW GND FB PIN DESCRIPTION PIN NO. 1 2 3 4 5 CMOS IC PIN NAME SW GND FB EN VCC DESCRIPTION Switching Pin. Ground Pin. Feedback Pin. Chip Enable & Dimming pin. Active high. Internal pull low. VCC Input Pin. BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 6 QW-R135-001.C UU28121 CMOS IC ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT VCC Pin Voltage VIN -0.3 ~ 6.5 V SW Pin Voltage VSW -0.3 ~ 30 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 270 °C/W Junction to Case θJC 110 °C/W Note: θJA is measured with the PCB copper are (need connect to GND of the UTC UU28121) of approximately 1 in2 (Multi-layer). ELECTRICAL CHARACTERISTICS (VIN=5V, VEN=5V, IOUT=20mA, TA=25°C, unless otherwise specified) PARAMETER SYMBOL TEST CONDITIONS Input Voltage Range VIN Input UVLO UVLO Rising UVLO Hysteresis Step-Up Voltage Adjust Range VOUT Quiescent Current ICCQ IOUT=0mA, VFB=1.5V Shutdown Current ISD VEN=0V FB Pin Voltage VFB FB Pin Current IFB VFB=1.3V Line Regulation VIN=2.5~5.5V, IOUT=20mA Load Regulation VIN=5V, IOUT=1mA~400mA Switching Frequency FOSC Maximum Duty DMAX N-Channel MOSFET Current Limit ILIM Duty=50% VCC=3V, ISW=1A MOSFET On-resistance RDS(on) VCC=5V, ISW=1A SW Leakage Current ISWL VSW=28V, VFB=1.5V EN High-level Input Voltage VIH EN Low-level Input Voltage VIL EN Hysteresis Hys Thermal Shutdown TDS Thermal Shutdown Hysteresis TSH UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN 2.5 TYP 2.25 0.2 3 MAX 5.5 2.45 28 150 250 1 4 1.213 1.238 1.263 ±100 0.2 0.2 900 1200 1500 87 90 1.6 600 500 1 1.4 0.4 200 150 35 UNIT V V V V μA μA V nA % % KHz % A mΩ μA V V mV °C °C 3 of 6 QW-R135-001.C UU28121 CMOS IC FUNCTION DESCRIPTION Setting the Output Voltage Application circuit item shows the basic application circuit with UTC UU28121 adjustable output version. The external resistor sets the output voltage according to the following equation: VOUT=1.238V×(1+ R2 ) R1 Table 1. Resistor Selection for Common Output Voltages VOUT(V) 12 16 24 27 R1(kΩ) 54 39 39 36 R2(kΩ) 470 470 720 750 For most applications, R2 is a suggested a value by 300K~850KΩ. Place the resistor-divider as close to the IC as possible to reduce the noise sensitivity. 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~200mV). 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 4.7µF 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 2.2uF 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 6 QW-R135-001.C UU28121 CMOS IC TYPICAL APPLICATION CIRCUIT 1. VOUT < 18V R3 100K C1 2.2uF D1 SB240 L1 4.7uH VIN=5V R1 470K U1 5 4 1 VCC SW EN FB 3 GND 2 C3 0.1uF VOUT=12V R2 54K C2 2.2uF VOUT=1.238V×(1+ R1 ) R2 R1 Suggest 300K~850K 2. VOUT ≥ 18V R3 100K C1 2.2uF D1 SB240 L1 2.2~4.7uH VIN=5V U1 5 4 1 VCC SW EN FB 3 C3 0.1uF GND 2 VOUT=24V R1 720K R2 39K C3 22pF C2 2.2uF VOUT=1.238V×(1+ R1 ) R2 R1 Suggest 300K~850K UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 6 QW-R135-001.C UU28121 CMOS IC TYPICAL CHARACTERISTICS 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 6 of 6 QW-R135-001.C