BL4056

www.belling.com.cn

V1.4

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Description of the Principle

The BL4056 is a complete constant-current/constant-voltage linear charger for single cell lithium-ion batteries.

Constant-current/constant-voltage to charger batter by internal MOSFET .It can deliver up to 1A of charge

current .No blocking diode or external current sense resistor is required. BL4056 include two Open-Drain charge

status Pins: Charge status indicator

and battery failure status output

.

The internal thermal regulation circuit reduces the programmed charge current if the die temperature attempts to

rise above a preset value of approximately 145℃. This feature protects the BL4056 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

BL4056 or the external components. Another benefit of adopting thermal regulation is that charge current can be set

according to typical, not worst-case, ambient temperatures for a given application with the

assurance that the charger will automatically reduce the current in worst-case conditions.

connected from the PROG pin to ground, and the CE pin is pulled above the chip enable threshold. The

pin

outputs a logic low to indicate that the charge cycle is on going. At the beginning of the charge cycle, if the battery

voltage is below 2.9V, the charge is in precharge mode to bring the cell voltage up to a safe level for charging. The

charger goes into the fast charge constant-current mode once the voltage on the BAT pin rises above 2.9 V. In

4.2V/4.34V, the charge current begins to decrease as the BL4056 enters the constant-voltage mode. When the

current drops to charge termination threshold, the charge cycle is terminated, and

pin assumes a high

impedance state to indicate that the charge cycle is terminated and

pin is pulled low. The charge termination

threshold is 10% of the current in constant current mode. To restart the charge cycle, remove the input voltage and

reapply it, or momentarily force CE pin to 0V. The charge cycle can also be automatically restarted if the BAT pin

voltage falls below the recharge threshold. The on-chip reference voltage, error amplifier and the resistor divider

provide regulation voltage with 1% accuracy which can meet the requirement of lithium-ion and lithium polymer

dropping battery drain current to less than 3µA. This greatly reduces the current drain on the battery and increases

the standby time. The charger can be shutdown by forcing the CE pin to GND.

The charging profile is shown in the following figure: