ME4057

V01

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Typical performance characteristics

Description of the Principle

The ME4057 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. ME4057 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 ME4057 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 ME4057 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.

The charge cycle begins when the voltage at the VCC pin rises above the UVLO level, a current set resistor is

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