LTC4054L-4.2 Datasheet, PDF (10/16 Pages) Linear Technology – 150mA Standalone Linear Li-Ion Battery Charger in ThinSOT

LTC4054L-4.2
U
OPERATIO
Manual Shutdown
At any point in the charge cycle, the LTC4054L can be put
into shutdown mode by removing R_PROG thus floating the
PROG pin. This reduces the battery drain current to less
than 2µA and the supply current to less than 50µA. A new
charge cycle can be initiated by reconnecting the program
resistor.
In manual shutdown, the CHRG pin is in a weak pull-down
state as long as V_CC is high enough to exceed the UVLO
conditions. The CHRG pin is in a high impedance state if
the LTC4054L is in undervoltage lockout mode: either V_CC
is within 100mV of the BAT pin voltage or insufficient
voltage is applied to the V_CC pin.
Automatic Recharge
Once the charge cycle is terminated, the LTC4054L con-
tinuously monitors the voltage on the BAT pin using a
comparator with a 2ms filter time (t_RECHARGE). A charge
cycle restarts when the battery voltage falls below 4.05V
(which corresponds to approximately 80% to 90% battery
capacity). This ensures that the battery is kept at or near
a fully charged condition and eliminates the need for
periodic charge cycle initiations. CHRG output enters a
strong pull-down state during recharge cycles.
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