LTC4054

Part: LTC4054 from Linear Technology Corporation

Type: Single Cell Lithium-Ion Linear Charger

Description: A complete constant-current/constant-voltage linear charger for single cell lithium-ion batteries, featuring programmable charge current up to 800mA, preset 4.2V charge voltage with ±1% accuracy, and thermal regulation in a ThinSOT package.

Operating Conditions:

• Supply voltage: 4.25–6.5 V
• Operating temperature: -40 to 85 °C
• Regulated output voltage: 4.2 V
• Max programmable charge current: 800 mA

Absolute Maximum Ratings:

• Max supply voltage: 10 V
• Max continuous current: 800 mA (BAT Pin Current, PROG Pin Current)
• Max junction/storage temperature: 125 °C (Junction), -65 to 125 °C (Storage)

Key Specs:

• Regulated Output (Float) Voltage (V FLOAT): 4.158 V min, 4.2 V typ, 4.242 V max (0 °C ≤ T A ≤ 85 °C, I BAT = 40mA)
• Input Supply Current (I CC) Charge Mode: 300 mA typ (R PROG = 10k)
• BAT Pin Current (I BAT) R PROG = 2k: 465 mA min, 500 mA typ, 535 mA max
• Trickle Charge Threshold Voltage (V TRIKL): 2.8 V min, 2.9 V typ, 3.0 V max (R PROG = 10k, V BAT Rising)
• C/10 Termination Current Threshold (I TERM): 0.085 mA/mA min, 0.10 mA/mA typ, 0.115 mA/mA max (R PROG = 10k)
• Power FET 'ON' Resistance (R ON): 600 mΩ typ (Between V CC and BAT)
• Junction Temperature in Constant Temperature Mode (T LIM): 120 °C typ
• V CC Undervoltage Lockout Threshold (V UV): 3.7 V min, 3.8 V typ, 3.92 V max (From V CC Low to High)

Features:

• Programmable Charge Current Up to 800mA
• No MOSFET, Sense Resistor or Blocking Diode Required
• Constant-Current/Constant-Voltage Operation with Thermal Regulation
• Charges Single Cell Li-Ion Batteries Directly from USB Port
• Preset 4.2V Charge Voltage with ±1% Accuracy
• C/10 Charge Termination

Applications:

• Cellular Telephones, PDAs, MP3 Players
• Charging Docks and Cradles
• Bluetooth Applications

Package:

• 5-Lead SOT-23

• n Programmable Charge Current Up to 800mA
• n No MOSFET, Sense Resistor or Blocking Diode Required
• n Complete Linear Charger in ThinSOT TM Package for Single Cell Lithium-Ion Batteries
• n Constant-Current/Constant-Voltage Operation with Thermal Regulation* to Maximize Charge Rate Without Risk of Overheating
• n Charges Single Cell Li-Ion Batteries Directly from USB Port
• n Preset 4.2V Charge Voltage with -1% Accuracy
• n Charge Current Monitor Output for Gas Gauging*
• n Automatic Recharge
• n Charge Status Output Pin
• n C/10 Charge Termination
• n 25 m A Supply Current in Shutdown
• n 2.9V Trickle Charge Threshold (LTC4054)
• n Available Without Trickle Charge (LTC4054X)
• n Soft-Start Limits Inrush Current
• n Available in 5-Lead SOT-23 Package

An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 120 C. This feature protects the LTC4054 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the LTC4054. The charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. ThinSOT power considerations are discussed further in the Applications Information section.