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.