Features
➤ Fast charge and conditioning of
nickel cadmium or nickel-metal
hydride batteries
➤ Hysteretic PWM switch-mode
current regulation or gated control
of an external regulator
➤ Easily integrated into systems or
used as a stand-alone charger
➤ Pre-charge qualification of temperature
and voltage
➤ Configurable, direct LED outputs
display battery and charge status
➤ Fast-charge termination by Δ temperature/
Δ time, peak volume detection,
-ΔV, maximum voltage,
maximum temperature, and maximum
time
➤ Optional top-off charge and
pulsed current maintenance
charging
➤ Logic-level controlled low-power
mode (< 5μAstandby current)

General Description
The bq2004 Fast Charge IC provides
comprehensive fast charge control
functions together with high-speed
switching power control circuitry on a
monolithicCMOS device.
Integration of closed-loop current
control circuitry allows the bq2004
to be the basis of a cost-effective solution
for stand-alone and systemintegrated
chargers for batteries of
one or more cells.
Switch-activated discharge-beforecharge
allows bq2004-based chargers
to support battery conditioning and
capacity determination.
High-efficiency power conversion is
accomplished using the bq2004 as a
hysteretic PWM controller for
switch-mode regulation of the charging
current. The bq2004 may alternatively
be used to gate an externally
regulated charging current.
Fast charge may begin on application
of the charging supply, replacement
replacement
of the battery, or switch depression.
For safety, fast charge is
inhibited unless/until the battery
temperature and voltage are within
configured limits.
Temperature, voltage, and time are
monitored throughout fast charge.
Fast charge is terminated by any of
the following:

Rate of temperature time
(ΔT/Δt)

Peak voltage detection (PVD)

Negative delta voltage (-ΔV)

Maximum voltage

Maximum temperature

Maximum time
After fast charge, optional top-off
and pulsed current maintenance
phases are available.