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.