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1、1 LTC4054-4.2/LTC4054X-4.2 405442xf FEATURES DESCRIPTIO U APPLICATIO S U TYPICAL APPLICATIO U Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT , LTC and LT are registered trademarks of Linear Technology Corporation. I Programmable Charge Current Up to 800mA I No MOSFET, Se
2、nse Resistor or Blocking Diode Required I Complete Linear Charger in ThinSOTTM Package for Single Cell Lithium-Ion Batteries I Constant-Current/Constant-Voltage Operation with Thermal Regulation* to Maximize Charge Rate Without Risk of Overheating I Charges Single Cell Li-Ion Batteries Directly from
3、 USB Port I Preset 4.2V Charge Voltage with 1% Accuracy I Charge Current Monitor Output for Gas Gauging* I Automatic Recharge I Charge Status Output Pin I C/10 Charge Termination I 25A Supply Current in Shutdown I 2.9V Trickle Charge Threshold (LTC4054) I Available Without Trickle Charge (LTC4054X)
4、I Soft-Start Limits Inrush Current I Available in 5-Lead SOT-23 Package I Cellular Telephones, PDAs, MP3 Players I Charging Docks and Cradles I Bluetooth Applications ThinSOT is a trademark of Linear Technology Corporation. *U.S.Patent No. 6,522,118 The LTC4054 is a complete constant-current/constan
5、t- voltage linear charger for single cell lithium-ion batteries. Its ThinSOT package and low external component count make the LTC4054 ideally suited for portable applications. Furthermore, the LTC4054 is specifically designed to work within USB power specifications. No external sense resistor is ne
6、eded, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current 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 externall
7、y with a single resistor. The LTC4054 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the LTC4054 automatically enters a low current state,
8、dropping the battery drain current to less than 2A. The LTC4054 can be put into shutdown mode, reducing the supply current to 25A. Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input volt
9、age. 600mA Single Cell Li-Ion Charger VCC 1.65k 4.2V Li-Ion BATTERY 405442 TA01a LTC4054-4.2 1F VIN 4.5V TO 6.5V BAT 4 3 5 2 PROG GND 600mA Complete Charge Cycle (750mAh Battery) TIME (HOURS) 0 CHARGE CURRENT (mA) 1.5 405442 TAO1b 0.51.02.0 700 600 500 400 300 200 100 0 4.75 4.50 4.25 4.00 3.75 3.50
10、 3.25 3.00 0.250.751.251.75 CONSTANT POWER CONSTANT VOLTAGE CONSTANT CURRENT CHARGE TERMINATED BATTERY VOLTAGE (V) VCC = 5V JA = 130C/W RPROG = 1.65k TA = 25C 2 LTC4054-4.2/LTC4054X-4.2 405442xf (Note 1) Input Supply Voltage (VCC). 0.3V to 10V PROG. 0.3V to VCC + 0.3V BAT0.3V to 7V CHRG 0.3V to 10V
11、BAT Short-Circuit Duration Continuous BAT Pin Current. 800mA PROG Pin Current 800A Maximum Junction Temperature125C Operating Ambient Temperature Range (Note 2) 40C to 85C Storage Temperature Range. 65C to 125C Lead Temperature (Soldering, 10 sec)300C TJMAX = 125C, (JA = 80C/W TO 150C/W DEPENDING ON
12、 PC BOARD LAYOUT) (N0TE 3) ORDER PART NUMBER S5 PART MARKING LTH7 LTADY SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITS VCCInput Supply VoltageG4.256.5V ICCInput Supply CurrentCharge Mode (Note 4), RPROG = 10kG3002000A Standby Mode (Charge Terminated)G200500A Shutdown Mode (RPROG Not Connected,G2550A VCC 2.
13、9V BAT 2.9V CHRG: STRONG PULL-DOWN CHARGE MODE FULL CURRENT CHRG: STRONG PULL-DOWN SHUTDOWN MODE CHRG: Hi-Z IN UVLO WEAK PULL-DOWN OTHERWISE PROG RECONNECTED OR UVLO CONDITION STOPS PROG FLOATED OR UVLO CONDITION ICC DROPS TO 25A POWER ON PROG 100mV STANDBY MODE NO CHARGE CURRENT CHRG: WEAK PULL-DOW
14、N 2.9V BAT 4.05V 405442 F01 Figure 1. State Diagram of a Typical Charge Cycle 10 LTC4054-4.2/LTC4054X-4.2 405442xf APPLICATIO S I FOR ATIO WUUU Stability Considerations The constant-voltage mode feedback loop is stable with- out an output capacitor provided a battery is connected to the charger outp
15、ut. With no battery present, an output capacitor is recommended to reduce ripple voltage. When using high value, low ESR ceramic capacitors, it is recom- mended to add a 1 resistor in series with the capacitor. No series resistor is needed if tantalum capacitors are used. In constant-current mode, t
16、he 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 pin, the charger is stable with program resistor values as high as 20k. How- ever, 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 the PROG pin is loaded with a capacitance, CPR
