ME4057

V01

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Likewise, for positive temperature coefficient thermistor in battery, we have RTH＞RTL and we can calculate:

We can conclude that temperature monitor range is independent of power supply voltage VCC and it only depends

on R1, R2, RTL and RTH: The values of RTH and RTL can be found in related battery handbook or deduced from testing

data. In actual application, if only one terminal temperature is concerned (normally protecting overheating), there is

no need to use R2 but R1. It becomes very simple to calculate R1 in this case.

Under Voltage lockout (UVLO)

An internal under voltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode

until VCC rises above the under voltage lockout threshold . If the UVLO comparator is tripped, the charger will not

come out of shutdown mode until VCC rises 140mV above the battery voltage.

Manual terminate

At any time of the cycle of charging will put the ME4057 into disable mode to pull CE pin to GND, or remove

RPROG （PROG pin is float）. This made the battery drain current to less than 2μA and reducing the supply current to

55

μA. To restart the charge cycle, set CE pin in high level or connect a programming resistor.

If ME4057 in the under voltage Lockout mode, the

and

are all in high impedance state, or VCC is

above BAT pin 140mV, or VCC is too low.

Auto restart

Once charge is

been terminated, ME4057 immediately use a 1.8ms filter time（ tRECHARGE ）on the termination

comparator to constant monitor the voltage on BAT pin.

If this voltage drops below the 4.02V recharge threshold

(about between 80% and 90% of VCC), another charge cycle begins. This ensured the battery maintained (or

approach) to a charge full status and avoid the requirement of restarting the periodic charging cycle. In the recharge

cycle,

pin enters a pulled down status.