CST4054 Descriptions:
The CST4054 is a complete constant-current/constant voltage linear charger for single cell lithium-ion batteries. Its Thin SOT package and low external component count make the CST4054 ideally suited for portable applications. Furthermore, the CST4054 is specifically designed to work wi thin 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 CST4054 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 CST4054 automatically enters a low current state, dropping the battery drain current to less than 2μA. The CST4054 can be put into shutdown mode, reducing the supply current to 25μA. Other features include charge current monitor, under voltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage.
CST4054 Features:
Programmable Charge Current Up to 500mA
No MOSFET, Sense Resistor or Blocking Diode Required
Complete Linear Charger in 5-Lead SOT-23 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
AutomaticRecharge
Charge Status Output Pin
C/10 Charge Termination
25μA Supply Current in Shutdown
2.9V Trickle Charge Threshold
Soft-Start Limits Inrush Current
When using a single lamp, the light is completely extinguished after fully charging..
CST4054 Applications:
Cellular Telephones, PDAs, MP3 Players
Charging Docks and Cradles
Bluetooth Applications.
CST4054 Equivalent Circuit or Application Circuit:
CST4054 Pinning:
CST4054 Pin Descriptions：
CST4054 Functional Block Diagram：
CST4054 Equivalent Circuit or Application Circuit:
CST4054 Pinning:
CST4054 Pin Descriptions：
CHRG(Pin 1):
Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20μA is connected to the CHRG pin, indicating an “AC present” condition. When the CST4054 detects an under voltage lockout condition, CHRG is forced high impedance.
GND(Pin 2)：
Ground.
BAT(Pin 3):
Charge Current Output. Provides charge current to the battery and regulates the final float voltage to 4.2V. An internal precision resistor divider from this pin sets the float voltage which is disconnected in shut down mode.
VCC (Pin 4):
Positive Input Supply Voltage. Provides power to the charger. VCC can range from 4.25V to 6.5V and should be bypassed with at least a 1μF capacitor. When VCC drops to within 30mV of the BAT pin voltage, the 4054 enters shutdown mode, dropping I BAT to less than 2μA.
PROG (Pin 5):
Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is programmed by connecting a 1% resistor, RPROG, to ground. When charging in constant-current mode, this pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula: IBAT = (VPROG/RPROG)×1000.
The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from ground allows a 3μA current to pull the PROG pin high. When it reaches the 1.21V shutdown threshold voltage, the charger enters shutdown mode, charging stops and the input supply current drops to 25μA. This pin is also clamped to approximately 2.4V. Driving this pin to voltages beyond the clamp voltage will draw currents as high as 1.5mA. Reconnecting RPROG to ground will return the charger to normal operation.
CST4054 Functional Block Diagram：
Business consulting
13823761625
Mail me