Features
➤ Fast charge and conditioning of
nickel cadmium or nickel-metal
hydride batteries
➤ Hysteretic PWM switch-mode
current regulation or gated con-
trol of an external regulator
➤ Easily integrated into systems or
used as a stand-alone charger
➤ Pre-charge qualification of tem-
perature and voltage
➤ Configurable, direct LED outputs
display battery and charge status
➤ Fast-charge termination by ∆ tem-
perature/∆ time, peak volume de-
tection, -∆V, maximum voltage,
maximum temperature, and maxi-
mum 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 con-
trol circuitry on a monolithic CMOS
device.
Integration of closed-loop current
control circuitry allows the bq2004
to be the basis of a cost-effective so-
lution for stand-alone and system-
integrated chargers for batteries of
one or more cells.
Switch-activated discharge-before-
charge allows bq2004E/H-based charg-
ers 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 charg-
ing current. The bq2004E/H may al-
ternatively be used to gate an exter-
nally 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 tempera-
ture and voltage are within config-
ured limits.
Temperature, voltage, and time are
monitored throughout fast charge.
Fast charge is terminated by any of
the following:
c110 Rate of temperature rise
(∆T/∆t)
c110 Peak voltage detection (PVD)
c110 Negative delta voltage (-∆V)
c110 Maximum voltage
c110 Maximum temperature
c110 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 differ-
ences between the two ICs are illus-
trated in Table 1. Display differ-
ences are shown in Table 2.
1
Fast-Charge ICs
bq2004E/H
DCMD Discharge command
DSEL Display select
VSEL Voltage termination
select
TM
1 Timer mode select 1
TM
2 Timer mode select 2
TCO Temperature cutoff
TS Temperature sense
BAT Battery voltage
1
PN2004E01.eps
16-Pin Narrow DIP
or Narrow SOIC
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
INH
DIS
MOD
V
CC

V
SS
LED
2
LED
1
SNS
DCMD
DSEL
VSEL
TM
1
TM
2
TCO
TS
BAT
SNS Sense resistor input
LED
1 Charge status output 1
LED
2 Charge status output 2
V
SS System ground
V
CC 5.0V ±10% power
MOD Charge current control
DIS Discharge control
output
INH Charge inhibit input
Pin Connections
6/99 E
Pin Names