ME2109ME2139ME2149优秀升压IC设计方案.doc

ME2109 ME2139 ME2149移动电源优秀升压 IC外置 MOSFETMEM2306 实际效率高，在 1.5A-3A 最佳低成本升压方案，IC 与外围器件温度可保证在常温ME2139 系列是采用 CMOS 升压型开关稳压器，其主要包括一个参考电压源，一个振荡电路，一个误差放 大器，一个相位补偿电路，通过 PWM / PFM 切换控制电路。随着外部低通态电阻 N 沟道功率 MOS，本产 品适用于需要高效率和高输出电流的应用。 ME2139 系列交换机操作 PFM 控制电路的占空比为 15的 PWM/ PFM 切换控制电路在轻负载，并防止 IC 工作电流效率下降。特点：低电压工作：启动保证从 0.9 V（IOUT = 1 mA）占空比：内置 PWM/ PFM 切换控制电路 1578。振荡频率：1.0MHz 的外部部件：线圈，二极管，电容器和晶体管输出电压范围：1.5V6.5 V输出电压精度：2软启动功能：2 毫秒。包装：SOT23-5应用范围：MP3 播放器，数字音频播放器数码相机，GPS，无线收发器便携式设备 ME2139 ULTRA-SMALL PACKAGE PWM/PFM SWITCHING CONTROLDescriptionSTEP-UP SWITCHING REGULATORFeatureThe ME2139 series is a CMOS step-up switching regulator which mainly consists of a reference voltage source, an oscillation circuit, an error amplifier, a phase compensation circuit, a PWM/PFM switching control circuit. With an external low-ON-resistance Nch Power MOS, this product is applicable to applications requiring high efficiency and high output current. The ME2139 series switches its operation to the PFM control circuit whose duty ratio is 15 % with to the PWM/PFM switching control circuit under a light load and to prevent decline in the efficiency by IC operation current.Selection GuidelLow voltage operation: Start-up is guaranteed from 0.9 V(IOUT =1 mA )lDuty ratio: Built-in PWM/PFM switching controlcircuit 15 to 78 % .loscillator frequency：1.0MHzlExternalparts:coil,diode,capacitor,and transistorlOutput voltage range: 1.5V 6.5 VlOutput voltage accuracy：2%lSoft start function: 2 mS.lPACKAGE：SOT23-5Typical ApplicationlMP3 players, digital audio playerslDigital cameras, GPS, wireless transceiverlPortable devicesPin ConfigurationTYPEPOSFIXPACKAGESWICHINGTRANSISTORCEFUNCTIONVDDFUNCTIONFBFUNCTIONFEATUREME2139FM5SOT23-5ExternalTransistorYesYesYesExt+FBPin informationSOT-23-5ME2139FPin NumberPin NameFunctionSOT23-51FBFeed Back voltage pin2VDDIC power supply pin3CEShutdown pin4GNDGND pin5EXTExternal transistor connection pinBlock DiagramAbsolute Maximum RangPARAMETERSYMBOLRATINGUNITVDD Pin VoltageVDD-0.36.5VEXT Pin VoltageEXT-0.3VDD+0.3VCE Pin VoltageVCE-0.3Vin+0.3VEXT Pin CurrentIEXT1000mAPower Dissipation (SOT23-5)Pd250mWOperating Temperature RangeTOpr-25+85Storage Temperature RangeTstg-40+125Electrical CharacteristicsME2139FMeasuring conditions：VDD=VCE=3.3V，Topt=25。Unless otherwise specified。ParameterSYMBOLCONDITIONMINTYPMAXUNITCircuitFeedback voltageVFB-1.2251.251.275V2Input voltageVIN-6V2Operation start voltageVST1IOUT=1mA-0.9V2Oscillation start voltageVST2No external parts, voltage applied to VOUT-0.7V1Operation holding voltageVHLDIOUT=1mA，Measured by decreasing VIN voltage gradually0.7-V2Current consumption 1ISS1VFB=VFB(S) 0.95-200-A1Current consumption 2ISS2VFB=1.5V-15-A1Current consumption during shutdownISSSVCE=0V-0.020.5A1EXT pin output currentIEXTHVEXT=VOUT-0.4V-25-mA1IEXTLVEXT=0.4V-40-mA1Feed back voltagetemperature coefficientTa=-25-85-50-ppm/2Oscillation frequencyFosc-0.81.01.2MHz1Max. duty ratioMAXDUTYVFB=VFB(S) 0.95-78-1PWM/PFMswitchingduty ratioPFMDUTYVFB=VFB(S) 1.5, no load-15-1Shutdown pin input voltageVSHMeasured the oscillation at EXT pin0.75-V1VSL1Judged the stop of oscillation at EXT pinVOUT1.5V-0.3V1VSL2VOUT1.5V-0.2V1Shutdown pin input voltageISHVCE=VFB(S)0.95-0.1-0.1A1ISLVCE=0V-0.1-0.1A1Soft start timetss-2-mS2EfficiencyEFFI-90-2Note:1. VOUT(S) is the set output voltage value, and VOUT is the typical value of the output voltage.2. VOUT(S) can be set by using the rate of VFB and output voltage setting resistors (R1, R2).3. VFB(S) is the set output voltage value.4. VDD/VOUT separate type:1.8VVDD6V is recommended to stabilize the output voltage and oscillation frequency.Test Circuit1.2.External parts（suggest）1、Diode use Schottky diode such as IN5817 orIN5819 (forward voltage drop:0.2V)2、Inductor：3.3H（r30m）3、Capacitor：ceramiccapacitor 22F（It is best to use two parallel connection ceramic capacitors）4、Feed back resistors:R1+R250KExternal parts selection for DC/DC converterThe relationship between major characteristics of the step-up circuit and characteristics parameters of the external parts are shown in Figure 1.For larger output current? For high efficiency? For smaller ripple voltage?OperationefficiencyStand-by efficiencySmaller inductanceLarger inductanceSmaller DC resistance of inductorLarge output capacitanceLarge output capacitanceWith MOSFET, smaller ONresistanceWith MOSFET, smaller input capacitanceWith bipolar transistor, smaller external resisitance RbWith bipolar transistor, larger external resistance RbFigure 1 Relationship between major characteristics of the step-up circuit and external parts1. InductorAn inductance has strong influence on maximum output current IOUT and efficiency .1. Figure 2 shows the relation between IOUT, and characteristics to L of ME2139F.Figure 2LIOUT and characteristicsThe peak current (IPK) increases by decreasing L and the stability of a circuit improves and IOUT increases. If L is furthermore made small, efficiency falls and in running short, IOUT decreases. ( Based on the current drive capabilityof external switching transistor.)The loss of IPK by the switching transistor decreases by increasing L and the efficiency becomes maximum at a certain L value. Further increasing L decreases efficiency due to the loss of DC resistance of the coil. Also, IOUT decreases, too.Oscillation frequency is higher, smaller one can be chose and also makes coil smaller. The recommended inductances are 2.2 to 4.7 H inductor for ME2139F.Choose a value for L by referring to the reference data because the maximum output current is due to the input voltage in an actual case. Choose an inductor so that IPK does not exceed the allowable current. Exceeding the allowable current of the inductor causes magnetic saturation, remarkable low efficiency and destruction of the IC chip due to a large current.IPK in uncontinuous mode is calculated from the following equation:I PK =2I OUT(VOUT+ VD- VI N)( A)f OSC .LFosc = oscillation frequency, VDD =0.4 V.2. DiodeUse an external diode that meets the following requirements: Low forward voltage: (VF0.3 V) High switching speed: (50 ns max.) Reverse voltage: VOUT + VF or more Rated current: IPK or more3. Capacitor (CIN, CO)To improve efficiency, an input capacitor (CIN)lowers the power supply impedance and averages the input current. Select CIN according to the impedance of the power supply used. The recommended capacitance is 10F for the ME2139F.An output capacitor (COUT), which is used to smooth the output voltage, requires a capacitance larger than thatofthe step-down type because the current is intermittently supplied from the input to the output side in the step-up type. A 22F ceramic capacitor is recommended for the ME2139F. However, a higher capacitance is recommended if the output voltage is high or the load current is large. If the output voltage or load current is low,about 10F can be used without problems.Select COUT after sufficient evaluation with actual application.A ceramic capacitor can be used for both the input and output.4. Enhancement MOS FET typeFor a MOS FET, an N-channel power MOS FET should be used. Because the gate voltage and current of the external power MOS FET are supplied from the stepped up output voltage VOUT, the MOS FET is driven more effectively.Depending on the MOS FET you use in your device, there is a chance of a current overrun at power ON. Thoroughly test all settings with your device before deciding on which one to use. Also, try to use a MOS FET with the input capacitance of 700 pF or less.Since the ON resistor of the MOS FET might depend on the difference between the output voltage VOUT and the threshold voltage of MOS FET, and affect the output current as well as the efficiency, the threshold voltage shouldbe low. When the output voltage is low, the circuit operates only when the MOS FET has the threshold voltage lower than the output voltage.5. Precautions Mount external capacitors, a diode, and a coil as close as possible to the IC. Unique ripple voltage and spike noise occur in switching regulators. Because they largely depend on the coil andthe capacitor used, check them using an actually mounted model.Make sure dissipation of the switching transistor (especially at a high temperature) does not exceed the allowablepower dissipation of the package.The performance of this IC varies depending on the design of the PCB patterns, peripheral circuits and external parts. Thoroughly test all settings with your device. Also, try to use recommended external parts.Typical Application CircuitFor FB and external 1For FB and external 2Typical Performance CharacteristicsVin=3.6VVin=3VVin=4.2VVin=4.2VVin=3VVin=3.6VPackage DimensionPackage type:SOT23-5Unit:mm(inch)DIMMillimetersInchesMinMaxMinMaxA0.91.450.03540.0570A100.1500.0059A20.91.30.03540.0511B0.20.50.00780.0196C0.090.260.00350.0102D2.73.100.10620.1220E2.23.20.08660.1181E11.301.800.05110.0708e0.95REF0.0374REFe11.90REF0.0748REFL0.100.600.00390.0236a00030000300 The information described herein is subject to change without notice. Nanjing Micro One Electronics Inc is not responsible for any problems caused by circuits or diagrams described herein whose related industrial properties, patents, or other rights belong to third parties. The application circuit examples explain