UC3380G-XX-AF5-R

UNISONIC TECHNOLOGIES CO., LTD UC3380 PWM STEP UP DC-DC CONTROLLER DESCRIPTION The UC3380 is PWM step up DC-DC switching controller that operates from 0.9V. The low start up input voltage makes UC3380 specially designed for powering portable equipment from one or two cells battery packs. This device consist of a soft start circuit, a reference voltage source, an error amplifier, an oscillator, a phase compensation, a PWM controller and an output drive circuit for driving external power transistor. Additionally, a chip enable feature is provided to power down the converter for extended battery life. The device features a voltage mode PWM control loop, providing stable and high efficiency operation over a broad load current range. CMOS IC FEATURES * 0.9V Low Start-Up Input Voltage at 1mA Load * Low Operation Current * 0.5uA Low Shutdown Current * Fix Frequency PWM at 100KHZ * Built in PWM Switching Control Circuit ,Duty Ratio is 0~83% * Output Voltage:0.1V Step Setting is Available Between 2.0V and 6.5V * Soft Start Time: 6ms * Shutdown Function APPLICATIONS *Portable Devices *Electronic Games *Portable Audio (MP3) *Personal Digital Assistant (PDA) *Digital still Cameras(DSC) *Camcorders *White LED Driver *Single and Dual-Cell Battery Operated Products ORDERING INFORMATION Ordering Number Lead Free Halogen Free UC3380L-xx-AF5-R UC3380G-xx-AF5-R Package SOT-25 Packing Tape Reel www.unisonic.com.tw 1 of 9 QW-R502-099.C Copyright © 2010 Unisonic Technologies Co., Ltd UC3380 MARKING INFORMATION PACKAGE VOLTAGE CODE 18:1.8V 21:2.1V 25:2.5V 27:2.7V 30:3.0V 33:3.3V 40:4.0V 50:5.0V MARKING CMOS IC SOT-25 PIN DESCRIPTION PIN NO 1 2 3 4 5 NAME SHUTDOWN VOUT NC VSS EXT DESCRIPTION Shutdown control input, “H” : normal operation “L” : stop step up( whole circuit stop). Power supply and voltage output. No connection. Ground. Switching the circuit by connecting to a transistor. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 9 QW-R502-099.C UC3380 BLOCK DIAGRAM CMOS IC UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 9 QW-R502-099.C UC3380 ABSOLUTE MAXIMUM RATINGS CMOS IC PARAMETER SYMBOL RATINGS UNIT VOUT Pin Voltage VOUT 12 V SHUTDOWN Pin Voltage VSHUTDOWN VSS-0.3~12 V EXT Pin Voltage VEXT -0.3~ VOUT+0.3 V EXT Pin Current IEXT ±80 mA Power Dissipation PD 250 mW Operating Ambient Temperature TOPR -40~+85 °C Storage Temperature TSTG -40~ +125 °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. ELECTRICAL CHARACTERISTICS Refer to the test circuit, TOPR=25ºC, VIN=VOUT (S)*0.6, IOUT=VOUT (S)/50Ω, unless otherwise specified. PARAMETER TOTAL DEVICE Output Voltage Supply Current 1 Supply Current 2 Input Voltage Operation Holding Voltage Operation Start Voltage Oscillation Start Voltage Oscillation Frequency Duty Ratio Line Regulation Load Regulation Temperature Coefficient Efficiency Soft Start time SHUTDOWN Shutdown Supply Current Shutdown Pin Input Current VOUT IS1 IS2 VIN VHOLD VST1 VST2 fOSC Duty ⊿LNR ⊿LDR ET EF Ts ISS ISH ISL VIH Shutdown Pin Input Voltage Threshold VIL1 V IL2 EXT EXT Pin Current IEXTH IEXTL 1 1 VEXT=VOUT (S) -0.4V VEXT= 0.4V -16.1 27.4 -32.3 54.8 mA mA 1 2 1 1 2 2 2 1 1 1 2 2 2 2 2 1 1 VSHUTDOWN=0 VSHUTDOWN=VOUT (S)*0.95 VSHUTDOWN=0 Shutdown pin “L” to “H” until EXT output oscillating signal Shutdown pin VOUT≥1.5V “H” to “L” until EXT output oscillating signal VOUT I PK *Reverse voltage: ≥ U O + U D *Rated current: 2. Inductor (L1) Low inductance values supply higher output current, but also increase the ripple and reduce efficiency. Choose a low DC-resistance inductor to minimize loss. It is necessary to choose an inductor with saturation current greater than the peak current that the inductor will encounter in the application. Saturation occurs when the inductor’s magnetic flux density reaches the maximum level the core can support and inductance falls. 3. Capacitor (C1, C3) The input capacitor C1 improves the efficiency by reducing the power impedance and stabilizing the input current. Select a C1 value according to the impedance of the power supply used. Small Equivalent Series Resistance (ESR) Tantalum or ceramic capacitor with an appropriate value should be suitable The output capacitor is used for smoothing the output voltage and sustaining the output voltage when the switch is on. Select an appropriate capacitor depending on the ripple voltage that increases in case of a higher output voltage or a higher load current. The capacitor value should be 10uF minimum. Small ESR should be used to reduce output ripple voltage. However, the best ESR may depend on L, capacitance, wiring and applications (output load). Therefore, fully evaluate ESR under an actual condition to determine the best value. 4. External transistor (Q1 R1 C2) An enhancement N-channel MOSFET or a bipolar NPN transistor can be used as the external switch transistor. *Bipolar NPN transistor The hFE value of NPN transistor and the R1 value determine the driving capacity to increase the output current using a bipolar transistor. 1KΩ is recommended for R1. R1 is selected from the following calculation. Calculate the necessary base current(Ib) from the bipolar transistor hFE using Ib = I PK hFE R1 = Vout − 0.7 0.4 − | I EXTH | Ib UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 9 QW-R502-099.C UC3380 EXTERNAL COMPONENTS(Cont.) CMOS IC Since the pulse current flows through the transistor, the exact Rb value should be finely tuned by the experiment. Generally, a small Rb value can increase the output current capability, but the efficiency will decrease due to more energy is used to drive the transistor. Moreover, a speed up capacitor, C2, should be connected in parallel with R1 to reduce switching loss and improve efficiency. C2 can be calculated by the equation below: C2 ≤ 1 2π × R1× fOSC × 0.7 It is due to the variation in the characteristics of the transistor used. The calculated value should be used as the initial test value and the optimized value should be obtained by the experiment. *Enhancement MOS FET For enhancement N-channel MOSFET, since enhancement MOSFET is a voltage driven, it is a more efficient switch than a BJT transistor. However, the MOSFET requires a higher voltage to turn on as compared with BJT transistors. An enhancement N-channel MOSFET can be selected by the following guidelines: -Input capacitance less than 700pF. -Low gate threshold voltage. -Low on-resistance. -The allowable maximum current of drain should be larger than peak current of inductor. 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 9 of 9 QW-R502-099.C