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UNISONIC TECHNOLOGIES CO., LTD UD05121 LINEAR INTEGRATED CIRCUIT www.unisonic.com.tw 1 of 7 Copyright © 2016 Unisonic Technologies Co., Ltd QW-R221-028.E 1.2A 1.5MHZ SYNCHRONOUS BUCK CONVERTER  DESCRIPTION The UTC UD05121 is a monolithic synchronous buck regulator with a built in internal power MOSFET. It achieves 1.2A continuous output current fix switching frequenc y with excellent load and line regulation. Current mode operation provides fast transient response and eases of loop stabilization. Fault condition protection includes cycle-by-cycle current limiting, output short circuit prot ection and thermal shutdown. In shutdown mode the regulator draws less than 1 μA of supply current. Internal soft-start minimi zes the inrush supply current at initial startup. The UTC UD05121 requires a minimum number of readily available standard external components.  FEATURES * 2.5V~5.5V input voltage range * Up to 1.2A Output Current * 300/200mΩ Internal Power MOSFET Switch * Stable with Low ESR Output Ceramic Capacitors * Up to 95% Efficiency * Less than 1μA Shutdown Current * 1.5Mhz Switching Frequency * Thermal Shutdown Protection * Current limit and short circuit protections. * Output Adjustable from 0.6V to V IN * Build-in soft start function  ORDERING INFORMATION Ordering Number Package Packing UD05121G-AF5-R SOT-25 Tape Reel  MARKING

UD05121 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 2 of 7 www.unisonic.com.tw Q W - R 2 2 1 - 0 2 8 . E  PIN CONFIGURATION 12 3 EN GND SW FB V CC  PIN DESCRIPTION PIN NO. PIN NAME DESCRIPTION 1 EN Chip enable pin. Active high.

2 GND Ground pin

3 SW Switching pin

4 V CC V CC input pin

5 FB Feedback pin

 BLOCK DIAGRAM EN FB GND SW VCC -EA0.6V UVLO and POR Reference And bias softatart COMP Thermal shutdown Driver OSCILLATOR ILimit PWM Control logic P-switch ISEN

UD05121 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 3 of 7 www.unisonic.com.tw Q W - R 2 2 1 - 0 2 8 . E  ABSOLUTE MAXIMUM RATING (TA= 25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT VCC Pin Voltage V IN -0.3~7 V SW Pin Voltage V SW -0.7 ~ V IN+0.3 V EN, FB Pins Voltage -0.3 ~ V IN+0.3 V Continuous Power Dissipation P D 370 mW Junction Temperature T J -40~125 °C Storage Temperature T STG -65~150 °C Notes: 1. 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. 2. Stresses exceed those ratings may damage the device.  THERMAL CHARACTERISTICS PARAMETER SYMBOL RATINGS UNIT Junction to Ambient θJA 270 °C/W Junction to Case θJC 85 °C/W Note: θJA is measured with the PCB copper are of approximately 1 in2 (Multi-layer).  ELECTRICAL CHARACTERISTICS (VIN=5V, VEN=5V, VOUT=1.8V, TA= 25°C) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Input Voltage V IN 2.5 5.5 V Input UVLO UVLO I OUT=0A 1.8 2.2 2.5 V Input OVLO OVLO I OUT=0A 6.0 V Quiescent Current I CCQ V FB=1V 250 350 μA Shutdown Current I SD V EN=0V 0.1 1 μA FB Pin Voltage V FB 0.588 0.6 0.612 V FB Pin Current I FB ±50 nA Load Regulation 0A<I OUT<1.2A 0.6 % Load Regulation 2.5A<V IN<5.5V 0.3 %/V EN Pin Voltage High V ENH 1.5 V EN Pin Voltage Low V ENL 0.4 V EN Pin Leakage Current V EN=3V 0.1 1 uA Switching Frequency F OSC 1.1 1.5 1.9 MHz Current Limit C L VIN=3V, VFB=0.5V or VOUT=90%, Duty Cycle<35% 1.4 1.7 A Switching Maximum Duty Dmax 100 % Minimum Duty Dmin 0 % P-Switch RDS(ON) R DS(ON)-P 300 m Ω N-Switch RDS(ON R DS(ON)-N 200 m Ω Low Side Discharger 60 Ω Thermal Shutdown T SD 160 °C Thermal Shutdown Protection hysteresis T SH 30 °C

UD05121 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 4 of 7 www.unisonic.com.tw Q W - R 2 2 1 - 0 2 8 . E  TYPICAL APPLICATION CIRCUIT EN GND FB SWVCCVIN 10uF OFF ON 22P 10uF 2.2uH VOUT VOUT=0.6x(1+R1/R2) VOUT=VFB × (1+R1/R2), VFB = 0.6V, R2 suggest 60k~300kΩ

schottky diode turns on until either the inductor current starts to reverse or the beginning of the next switching cycle. Table 1. Resistor select for output voltage setting one cycle until it reaches 100% duty cycle. The output voltage is dropped from the input supply for the voltage which across the high-side switch. reducing normal switching frequency to reduce power delivered from input to output.

UD05121 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 6 of 7 www.unisonic.com.tw Q W - R 2 2 1 - 0 2 8 . E  TYPICAL CHARACTERISTICS C1=100μF, C2=330μF, L1=33μH, TA=25°C Efficiency Test (VOUT=1.0V) Output Current, IOUT (A) Efficiency, EFF (%) 0 0.5 1.0 100 1.5 Output Current, IOUT (A) Efficiency, EFF (%) Efficiency Test (VIN=5V) Frequency vs. Input Voltage Quiescent Current vs. Input Voltage VIN=5V, VOUT=1.0V, ILOAD=No Load V IN=5V, VOUT=1.0V, IOUT=1.2A SWVIN VOUTVOUT IOUT VIN 5VIN 3.6VIN 2.7VIN 0 0.5 1.0 100 1.5 IOUT SW Input Voltage, VIN (V) Switch Frequency, FOSC (MHz) 2.5 3.5 4.5 1.50 1.45 1.40 1.35 1.25 1.20 1.30 5.53.0 4.0 5.0 Input Voltage, VIN (V) Quiescent Current, ICCQ (mA) 2.5 3.5 4.5 0.50 0.40 0.35 0.25 0.20 0.10 0.05 0.15 0.30 5.5 0.45 3.0 4.0 5.0 VOUT=1V

UD05121 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 7 of 7 www.unisonic.com.tw Q W - R 2 2 1 - 0 2 8 . E 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.