Features
* Se quen tial fast charge and con d-i
tioning of two NiCd or NiMH nickel
cad mium or nickel-metal hy dride
bat tery packs
* Hysteretic PWM switch-mode cur -
rent reg u la tion or gated con trol of
an ex ter nal reg u la tor
* Easily in te grated into sys tems or
used as a stand-alone charger
* Pre-charge qual i fi ca tion of tem per ature
and volt age
* Di rect LED out puts dis play bat tery
and charge sta tus
* Fast-charge ter mi na tion by
D temperature/D time, -DV, max i mum
volt age, max i mum tem per a ture, and
max i mum time
* Op tional top-off and pulse-trickle
charg ing

General Description
The bq2005 Fast-Charge IC pro vides
com pre hen sive fast charge con trol
func tions to gether with high-speed
switching power con trol cir cuitry on a
mono lithic CMOS de vice for se quential
charge man age ment in dual bat tery
pack ap pli ca tions.
In te gra tion of closed-loop cur rent con -
trol cir cuitry al lows the bq2005 to be
the ba sis of a cost-effective so lution
for stand-alone and sys tem-integrated
charg ers for bat ter ies of one or more
cells.
S w i t c h - a c t i v a t e d
dis-charge-before-charge al lows
bq2005-based charg ers to sup port bat -
tery conditioning and ca pac ity de ter m-i
nation.
High-efficiency power con ver sion is ac -
com plished us ing the bq2005 as a
hysteretic PWM con trol ler for
switch-mode reg ulation of the charg ing
cur rent. The bq2005 may al ternatively
be used to gate an ex ter nally reg u -
lated charging cur rent.
Fast charge may be gin on ap pli ca tion
of the charg ing sup ply, re place ment of
the bat tery, or switch de pres 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, volt age, and time are
mon i tored through out fast charge.
Fast charge is ter mi nated by any of
the fol low ing:
n Rate of temperature rise
(DT/Dt)
n Negative delta voltage (-DV)
n Maximum voltage
n Maximum temperature
n Maximum time
Af ter fast charge, op tional top-off and
pulsed cur rent main te nance phases
are avail able.