ME4054_E3.0.doc

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1、如有侵权，请联系网站删除，仅供学习与交流ME4054_E3.0【精品文档】第 11 页Standalone Linear Li-Ion Battery Charger in ThinSOT ME4054-4.2VGeneral Description Featuresl Programmable Charge Current Up to 800mAl No MOSFET, Sense Resistor or Blocking Diode Requiredl Complete Linear Charger in ThinSOT Package for Single Cell Lithium-Io

2、n Batteriesl Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charge Rate Without Risk of Overheatingl Charges Single Cell Li-Ion Batteries Directly from USB Portl Preset 4.2V Charge Voltage with 1% Accuracyl Automatic Rechargel Charge Status Output Pinl C/10 Charge Te

3、rmination l 25A Supply Current in Shutdownl 2.9V Trickle Charge Thresholdl Soft-Start Limits Inrush Currentl Available in 5-Lead SOT-23 PackageME4054 is a constant-current/constant-voltage linear charger for single cell lithium-ion batteries. Its Thin SOT package and low external component count mak

4、e the ME4054 ideally suited for portable applications. Furthermore, the ME4054 is specifically designed to work within USB power specifications.No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge curre

5、nt to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The ME4054 automatically terminates he charge cycle when the charge current drops to 1/10th the pr

6、ogrammed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the ME4054 automatically enters a low current state, dropping the battery drain current to less than 2A.The ME4054 can be put into shutdown mode, reducing the supply current to 25A

7、.Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage.Applicationsl Cellular Telephones, PDAs, MP3 Playersl Charging Docks and Cradlesl Bluetooth ApplicationsVIN4.5V TO 6.5V600mA S

8、ingle Cell Li-Ion ChargerComplete Charge Cycle (750mAh Battery)ME4054TIME(HOURS)CHARGE CURRENT(mA)4.754.54.254.03.753.53.253.0BATTERY VOLTAGE(V)0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 7006005004003002001000CONSTANT VOLTAGAECONSTANT CURRENTCONSTANTPOWER VCC=5VJA=130/WRPROG=1.65KTA=25CHARGE TERMINATED4V

9、CC5PROG3BAT600mA4.2VLi-IonBATTERY1.65K2GND1FPin Configuration1CHRGGNDBATPROGVCC5432 Pin AssignmentPinSymbolDescriptionSOT23-51CHRGOpen-Drain Charge Status Output2GNDGround JA3BATCharge Current Output4VCCPositive Input Supply Voltage5PROGCharge Current ProgramBlock Diagram CA5A3AVCCTO BAT2.9V43521CHR

10、GGNDPROGSHDNC3C2C1R31VR40.1VR5REF1.22VR2R1BAT1000xVAMA1xVCCTATDIE120 Absolute Maximum RatingsParameterRatingsInput Supply Voltage (VCC)0.3V10VPROG-0.3VVcc0.3VBAT-0.3V7VCHRG-0.3V10VBAT Short-Circuit DurationContinuousBAT Pin Current800mAPROG Pin Current800AMaximum Junction Temperature125Operating Amb

11、ient Temperature Range-4085Storage Temperature Range-65125Lead Temperature (Soldering, 10 sec)260Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be exceeded under any conditions.Electrical Characteristic

12、sSYMBOLPARAMETERCONDITIONSMINTYPMAXUnitVCCInput Supply Voltage4.256.5VICCInput Supply CurrentCharge Mode，RPROG=10K-3002000AStandby Mode (Charge Terminated)-200500AShutdown Mode（RPROG Not Connected，VCC2.9VPROG100mVPROG FLOATEDORUVLO CONDITIONSHUNDOWN MODEICC DROPS TO25ACHRG:HI-Z IN UVLOWEAK PULL-DOWN

13、OTHERWISESTANDBY MODENO CHARGE CURRENTCHRG:WEAKPULL-DOWNCHARGE MODEFULL CURRENTCHRG:STRONGPULL-DOWNTRICKLE CHARGEMODE1/10TH FULL CURRENTCHRG:STRONGPULL-DOWN2.9V4.05VBAT2.9VBAT2.9VPOWER ONFig.1 State Diagram of a Typical Charge CycleApplication Information1.Stability ConsiderationsThe constant-voltag

14、e mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. With no battery present, an output capacitor is recommended to reduce ripple voltage (as Fig.2). When using high value, low ESR ceramic capacitors, it is recommended to add a 1 resistor

15、in series with the capacitor. No series resistor is needed if tantalum capacitors are used. In constant-current mode, the PROG pin is in the feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the PROG pin. With no additional capacitance on the PROG pi

16、n, the charger is stable with program resistor values as high as 20K. However, additional capacitance on this node reduces the maximum allowed program resistor. The pole frequency at the PROG pin should be kept above 100KHz. Therefore, if IPROG pin is loaded with a capacitance CPROG, the following e

17、quation should be used to calculate the maximum resistance value for RPROG： Fig.2Average, rather than instantaneous, charge current may be of interest to the user. For example, if a switching power supply operating in low current mode is connected in parallel with the battery, the average current be

18、ing pulled out of the BAT pin is typically of more interest than the instantaneous current pulses. In such a case, a simple RC filter can be used on the PROG pin to measure the average battery current as shown in Fig.3. A 10K resistor has been added between the PROG pin and the filter capacitor to e

19、nsure stability. Fig.3 Isolating Capacitive Load on PROG Pin and Filtering2.Power dissipation The conditions that cause the ME4054 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the IC. Nearly all of this power dissipation is generated by the internal MOSFET-this is calculated t