Fast Chargeer. BQ2005 Datasheet
Fast-Charge IC for Dual-
∗ Sequential fast charge and con d-i
tioning of two NiCd or NiMH nickel
cadmium or nickel-metal hydride
bat tery packs
∗ Hysteretic PWM switch-mode cur -
rent regulation or gated control of
∗ Easily integrated into systems or
used as a stand-alone charger
∗ Pre-charge qual i fi ca tion of tem per a-
ture and volt age
∗ Direct LED outputs dis play bat tery
and charge sta tus
∆ temperature/∆ time, -∆V, max i mum
volt age, max i mum tem per a ture, and
max i mum time
∗ Optional top-off and pulse-trickle
The bq2005 Fast-Charge IC provides
comprehensive fast charge control
functions together with high-speed
switching power control circuitry on a
monolithic CMOS device for sequential
charge man age ment in dual battery
In te gra tion of closed-loop cur rent con-
trol circuitry allows the bq2005 to be
the basis of a cost-effective solution
for stand-alone and sys tem-integrated
charg ers for bat ter ies of one or more
bq2005-based chargers to support bat-
tery conditioning and capacity determ-i
High-efficiency power con ver sion is ac-
complished using the bq2005 as a
hysteretic PWM controller for
switch-mode regulation of the charging
cur rent. The bq2005 may alternatively
be used to gate an externally reg u-
lated charging cur rent.
Fast charge may begin on ap pli ca tion
of the charg ing sup ply, re place ment of
the battery, or switch depres sion. For
safety, fast charge is in hib ited un-
less/un til the bat tery tem per a ture and
volt age are within con fig ured lim its.
Temperature, voltage, and time are
monitored throughout fast charge.
Fast charge is ter mi nated by any of
the fol low ing:
n Rate of temperature rise
n Negative delta voltage (-∆V)
Af ter fast charge, op tional top-off and
pulsed current maintenance phases
are avail able.
SLUS079A - AU GUST 2000 G
DCMDA Dis charge com mand in put,
bat tery A
DVEN -DV en able
TM1 Timer mode se lect 1
TM2 Timer mode se lect 2
Tem pera ture sense in put,
bat tery A/B
SNSA, Sense re sis tor in put ,
Dis charge con trol out put,
bat tery A
Charge status out put,
bat tery A/B
FCCA, Fast charge com plete out put,
VSS Sys tem ground
VCC 5.0V±10% power
MODA, Charge cur rent con trol
MODB out put, bat tery A/B
DCMDA Discharge-before-charge control input,
DCMDA controls the discharge-before-charge
function of the bq2005. A negative-going
pulse on DCMDA initiates a discharge to
EDV followed by a charge if conditions allow.
By tying DCMDA to ground, automatic
discharge-before-charge is enabled on every
new charge cycle start.
-∆ V enable input
This input enables/disables -∆ V charge termi-
nation. If DVEN is high, the -∆ V test is en-
abled. If DVEN is low, -∆ V test is disabled.
The state of DVEN may be changed at any
Timer mode inputs
TM1 and TM2 are three-state inputs that con-
figure the fast charge safety timer, -∆V hold-
off time, and that enhance/disable top-off.
See Table 2.
Temperature cutoff threshold input
Input to set maximum allowable battery
temperature. If the potential between TSA
and SNSA or TSB and SNSB is less than the
voltage at the TCO input, then fast charge or
top-off charge is terminated for the corre-
sponding battery pack.
Temperature sense inputs
Input, referenced to SNSA or SNSB, respec-
tively, for an external thermistor monitoring
The battery voltage sense input, referenced to
SNSA,B, respectively. This is created by a
high-impedance resistor divider network con-
nected between the positive and the negative
terminals of the battery.
Charging current sense inputs,
SNSA,B controls the switching of MODA,B
based on the voltage across an external
sense resistor in the current path of the bat-
tery. SNS is the reference potential for the
TS and BAT pins. If SNS is connected to
VSS, MOD switches high at the beginning of
charge and low at the end of charge.
Discharge control output
Push-pull output used to control an external
transistor to discharge battery A before
Charge status outputs
Push-pull outputs indicating charging status
for batteries A and B, respectively. See Fig-
ure 1 and Table 2.
Fast charge complete outputs
Open-drain outputs indicating fast charge
complete for batteries A and B, respectively.
See Figure 1 and Table 2.
Charge current control outputs
MODA,B is a push-pull output that is used to
control the charging current to the battery.
MODA,B switches high to enable charging
current to flow and low to inhibit charging
current flow to batteries A and B,
VCC supply input
5.0 V, ±10% power input.