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 (< 5μA standby current)

General Description
The bq2004E and bq2004H Fast
Charge ICs provide comprehensive
fast charge control functions together
with high-speed switching power control
circuitry on a monolithic CMOS
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 bq2004E/H-based chargers
to support battery conditioning
and capacity determination.
High-efficiency power conversion is
accomplished using the bq2004E/H as
a hysteretic PWM controller for
switch-mode regulation of the charging
current. The bq2004E/H may alternatively
be used to gate an externally
regulated charging current.
Fast charge may begin on application
of the charging supply, 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 rise
(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 with appropriate display
mode selections are available.
The bq2004H differs from the
bq2004E only in that fast charge,
hold-off, and top-off time units have
been scaled up by a factor of two,
and the bq2004H provides different
display selections. Timing differences
between the two ICs are illustrated
in Table 1. Display differences
are shown in Table 2.