Features
➤ Safe charge of Lithium Ion battery
packs
➤ Voltage-regulated currentlimited
charging
➤ Fast charge terminated by selectable
minimum current; safety
backup termination on maximum
time
➤ Charging continuously qualified
by temperature and voltage limits
➤ Pulse-width modulation control
ideal for high-efficiency switchmode
power conversion
➤ Direct LED control outputs display
charge status and fault conditions

General Description
The bq2054 Lithium Ion Fast-
Charge IC is designed to optimize
charging of lithium ion (Li-Ion)
chemistry batteries. A flexible
pulse-width modulation regulator
allows the bq2054 to control voltage
and current during charging. The
regulator frequency is set by an external
capacitor for design flexibility.
The switch-mode design keeps
power dissipation to a minimum.
The bq2054 measures battery temperature
using an external thermistor
for charge qualification. Charging
begins when power is applied or on
battery insertion.
For safety, the bq2054 inhibits
charging until the battery voltage
and temperature are within configured
limits. If the battery voltage
is less than the low-voltage threshold,
the bq2054 provides low-current
conditioning of the battery.
A constant current-charging phase replenishes
up to 70% of the charge capacity,
and a voltage-regulated phase
returns the battery to full. The charge
cycle terminates when the charging
current falls below a user-selectable
current limit. For safety, charging terminates
after maximum time and is
suspended if the temperature is outside
the preconfigured limits.
The bq2054 provides status indications
of all charger states and faults
for accurate determination of the
battery and charge system conditions.