UNISONIC TECHNOLOGIES CO., LTD UC3380 CMOS IC 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. FEATURES * 0.9V Low Start-Up Input Voltage at 1mA Load * Low Operation Current * 0.5uA Low Shutdown Current * Fix Frequency PWM at 300KHZ * Built in PWM Switching Control Circuit ,Duty Ratio is 0~78% * Output Voltage:0.1V Step Setting is Available Between 2.0V and 6.5V * Soft Start Time: 3ms * 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 www.unisonic.com.tw Copyright © 2012 Unisonic Technologies Co., Ltd Package Packing SOT-25 Tape Reel 1 of 9 QW-R502-099.D UC3380 CMOS IC MARKING INFORMATION PACKAGE VOLTAGE CODE SOT-25 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 PIN DESCRIPTION PIN NO NAME 1 SHUTDOWN 2 3 4 5 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. BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 9 QW-R502-099.D UC3380 CMOS IC ABSOLUTE MAXIMUM RATINGS 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=25°C, VIN=VOUT (S)*0.6, IOUT=VOUT (S)/50Ω, unless otherwise specified. TEST TEST CONDITION MIN TYP PARAMETER SYMBOL CIRCUIT TOTAL DEVICE VOUT VOUT Output Voltage VOUT 2 (S) (S)*0.976 VOUT (S)15 to 19 33.8 VOUT (S)20 to 29 50.3 VOUT (S)30 to 39 68.6 VOUT= Supply Current 1 IS1 1 VOUT (S)*0.95 VOUT (S)40 to 49 88.4 VOUT (S)50 to 59 109.4 VOUT (S)60 to 65 131.6 VOUT (S)15 to 19 9.7 VOUT (S)20 to 29 9.9 V (S)30 to 39 10.0 VOUT= OUT Supply Current 2 IS2 1 VIN (S)+0.5V VOUT (S)40 to 49 10.2 VOUT (S)50 to 59 10.4 VOUT (S)60 to 65 10.5 Input Voltage VIN 2 Measured by decreasing VIN Operation Holding Voltage VHOLD 2 voltage gradually, when 0.7 IOUT=1mA. Operation Start Voltage VST1 2 IOUT=1mA Increase the VIN until EXT pin Oscillation Start Voltage VST2 1 output the oscillating signal Oscillation Frequency fOSC 1 VOUT=VOUT (S)*0.95 255 300 Duty Ratio Duty 1 VOUT=VOUT (S)*0.95 70 78 ⊿LNR Line Regulation 2 VIN=VOUT (S)*0.4 to *0.6 30 ⊿LDR Load Regulation 2 IOUT=10uA to VOUT (S)/50*1.25 30 ⊿VOUT/(⊿TOPR*VOUT) ±50 Temperature Coefficient ET 2 TOPR=-40°C ~ +85°C Efficiency EF 2 85 Soft Start time Ts 2 1.5 3.0 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MAX VOUT (S)*1.024 56.4 83.9 114.4 147.4 182.4 219.3 19.4 19.7 20.0 20.4 20.7 21.0 10 UNIT V uA uA V V 0.9 V 0.8 V 345 85 60 60 KHz % mV mV ppm/°C 6.0 % ms 3 of 9 QW-R502-099.D UC3380 CMOS IC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL SHUTDOWN Shutdown Supply Current Shutdown Pin Input Current ISS ISH ISL TEST CIRCUIT 1 1 VIH Shutdown Pin Input Voltage Threshold VIL1 V IL2 1 TEST CONDITION VSHUTDOWN=0 VSHUTDOWN=VOUT (S)*0.95 VSHUTDOWN=0 Shutdown pin “L” to “H” until EXT output oscillating signal Shutdown pin “H” to VOUT≥1.5V “L” until EXT output VOUT<1.5V oscillating signal MIN TYP MAX UNIT 0.5 0.1 -0.1 uA uA uA 0.75 V 0.3 V 0.2 V EXT VOUT (S)15 to 19 VOUT (S)20 to 24 VOUT (S)25 to 29 VEXT= 1 VOUT (S)30 to 39 IEXTH VOUT (S) -0.4V VOUT (S)40 to 49 VOUT (S)50 to 59 VOUT (S)60 to 65 EXT Pin Current VOUT (S)15 to 19 VOUT (S)20 to 24 VOUT (S)25 to 29 IEXTL 1 VEXT= 0.4V VOUT (S)30 to 39 VOUT (S)40 to 49 VOUT (S)50 to 59 VOUT (S)60 to 65 Note: VOUT (S) is the value of the set output voltage. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw -4.5 -6.2 -7.8 -10.3 -13.3 -16.1 -18.9 9.5 12.6 15.5 19.2 23.8 27.4 30.3 -8.9 -12.3 -15.7 -20.7 -26.7 -32.3 -37.7 19.0 25.2 31.0 38.5 47.6 54.8 60.6 mA mA 4 of 9 QW-R502-099.D UC3380 CMOS IC APPLICATION CIRCUIT TEST CIRCUIT 1. 2. VIN + + - - 47u + EXT VOUT 0.1u 47u - V SHUTDOWN VSS UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 9 QW-R502-099.D UC3380 CMOS IC APPLICATION CIRCUIT INFORMATION The following equations show the relation of the basic design parameters. 1. Refer to the application circuit, the increasing inductor current when the switch is turn on is given by the following equation 1 1 d ( UIN : input voltage: US : transistor saturation voltage) Δi L + = ULTON = (UIN − US ) L L f The decreasing inductor current when the switch is turn off can derive by the equation below 1 1 1− d ( UD ：diode forward voltage) Δi L − = ULTOFF = − (UO + UD − UIN ) L L f according to Δi L + + Δi L − = 0 , the duty ratio is given by d= UO + UD − UIN UO + UD − US IO 1− d I then we can write: IO = (1 − d ) L • Δi L Δi L 2. The average current flowing through the inductor is IL = 3. We note that IO = (1 − d )IL 1 ULTOFF Δi L for equation above, output current is given by L Δi 1 1 ( ICR = L ) IO = (1 − d ) • • ULTOFF IL ICR L substituting Δi L = 1 1 1− d • (Uo + UD − UIN ) ICR L f UO + UD − UIN 2 IO = (1 − d ) • ICR • L • f derive that IO = (1 − d ) • 4. The peak current of the inductor is given by 1 IPK = IL + Δi L 2 1 Δi L IPK = IL + • IL 2 IL according to ICR = Δi L derive that IL 1 ICR • IL 2 Then derive the following equation for peak current of inductor 1 IPK = IL (1 + ICR ) 2 5. Charge stores in C3 during charging up is given by ΔQ = IC • TOFF IPK = IL + we can write ΔQ = (IL − IO ) • 1− d f UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 9 QW-R502-099.D UC3380 CMOS IC APPLICATION CIRCUIT INFORMATION (Cont.) 6. Output ripple voltage is given by VPP = ΔUC + ESR • (IL − IO ) (ESR: equivalent series resistance of the output capacitor) ΔQ + ESR • (IL − IO ) C Then we give the following example about choosing external components by considering the design parameters. Design parameters: UIN=1.5V UO=2.1V IO=200mA VPP=100mV f=300KHz ICR=0.2 Assume UD and US are both 0.3V, the duty ratio is U + UD − UIN 2.1 + 0.3 − 1.5 d= O = = 0.429 UO + UD − US 2.1 + 0.3 − 0.3 VPP = In order to generate the desired output current and ICR, the value of inductor should meets the following formula L≤ (1– d)2(UO+UD-UIN) ICR • IO • f = (1– 0.429)2(2.1V+0.3V-1.5V) = 24.5uH 0.2×0.2A×300000HZ Calculate the average current and the peak current of inductor I 0.2 A IL = O = = 0.35 A 1 − d 1 − 0.429 1 1 IPK = IL (1 + ICR ) = 0.35 A × (1 + × 0.2) = 0.385 A 2 2 So, we make a trial of choosing a 22uH inductor that allowable maximum current is lager than 0.385A. Determine the delta charge stores in C3 during charging up 1− d 1 − 0.429 ΔQ = (IL − IO ) • = (0.35 A − 0.2 A) × = 0.286uC f 300000HZ Assume the ESR of C3 is 0.15Ω, determine the value of C3 ΔQ 0.286 × 10 −6 C C≥ = = 3.69uF VPP − ESR • (IL − IO ) 0.1 − 0.15Ω × (0.35 A − 0.2 A) Therefore, a Tantalum capacitor with value of 10uF and ESR of 0.15Ω can be used as output capacitor. However, the optimized value should be obtained by experiment. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 9 QW-R502-099.D UC3380 CMOS IC EXTERNAL COMPONENTS 1. Diode (D1) The diode is the largest source of loss in DC-DC converters. The most important parameters which affect the efficiency are the forward voltage drop UD and the reverse recovery time. The forward voltage drop creates a loss just by having a voltage across the device while a current flowing through it. The reverse recovery time generates a loss when the diode is reverse biased, and the current appears to actually flow backwards through the diode due to the minority carriers being swept from the P-N junction. A Schottky diode with the following characteristics is recommended: *Low forward voltage: UD<0.3V *Fast reverse recovery time/switching speed: ≦50nS *Rated current: >IPK *Reverse voltage: ≧UO+UD 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. I Calculate the necessary base current(Ib) from the bipolar transistor hFE using Ib = PK hFE R1 = VOUT − 0.7 0.4 − Ib | IEXTH | 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: 1 C2 ≤ 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. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 9 QW-R502-099.D UC3380 CMOS IC 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.D