New Content (1)
Application NotesAN-171: Reverse Voltage Protection for Battery Chargers
Features and Benefits
- Programmable Charge Current Up to 800mA
- No MOSFET, Sense Resistor or Blocking Diode Required
- Complete Linear Charger in ThinSOT™ Package for Single Cell Lithium-Ion Batteries
- Constant-Current/Constant-Voltage Operation with Thermal Regulation* to Maximize Charge Rate Without Risk of Overheating
- Charges Single Cell Li-Ion Batteries Directly from USB Port
- Preset 4.2V Charge Voltage with ±1% Accuracy
- Charge Current Monitor Output for Gas Gauging*
- Automatic Recharge
- Charge Status Output Pin
- C/10 Charge Termination
- 25µA Supply Current in Shutdown
- 2.9V Trickle Charge Threshold (LTC4054)
- Available Without Trickle Charge (LTC4054X)
- Soft-Start Limits Inrush Current
- Available in 5-Lead SOT-23 Package
The LTC4054 is a complete constant-current/constant-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 needed, 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 externally 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, dropping the battery drain current to less than 2µA. The LTC4054 can be put into shutdown mode, reducing the supply current to 25µA.
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.
|Max Charge Current||Trickle Charge|
- Cellular Telephones, PDAs, MP3 Players
- Charging Docks and Cradles
- Bluetooth Applications
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 569 is a single cell Li-Ion linear charger in a SOT-23. Charge rates as high as 600mA can be achieved due to the LTC4054’s internal die temperature control loop that prevents excessive PCB heating under worst-case conditions. The user is provided with a control jumper to select between OFF/450mA/600mA charge rates. The reduced charge rate is suitable for USB applications. A charge LED illuminates while the charger is charging the battery.
Tools & Simulations
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Sample & Buy
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