Features
➤ Sequential fast charge and con-
ditioning of two NiCd or NiMH
nickel cadmium or nickel-metal
hydride battery packs
➤ 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
➤ Direct LED outputs display
battery and charge status
➤ Fast-charge termination by
∆ temperature/∆ time, -∆V, maxi-
mum voltage, maximum tem-
perature, and maximum time
➤ Optional top-off and pulse-
trickle charging
General Description
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 management in dual battery
pack applications.
Integration of closed-loop current
control circuitry allows the bq2005
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 bq2005-based chargers
to support battery conditioning and
capacity determination.
High-efficiency power conversion is
accomplished using the bq2005 as a
hysteretic PWM controller for
switch-mode regulation of the charg-
ing current. The bq2005 may alterna-
tively 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 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 Negative delta voltage (-∆V)
c110 Maximum voltage
c110 Maximum temperature
c110 Maximum time
After fast charge, optional top-off
and pulsed current maintenance
phases are available.
1
Fast-Charge IC
for Dual-Battery Packs
bq2005
Pin Connections Pin Names
SLUS079–JUNE 1999 F
DCMD
A
Discharge command input,
battery A
DVEN -∆V enable
TM
1
Timer mode select 1
TM
2
Timer mode select 2
TCO Temperature cut-off
TS
A
, Temperature sense input,
TS
B
battery A/B
BAT
A
, Battery voltage input,
BAT
B
battery A/B
SNSA, Sense resistor input ,
SNSB battery A/B
1
PN200501.eps
20-Pin DIP or SOIC
2
3
4
5
6
7
8
20
19
18
17
16
15
14
13
9
10
12
11
DCMD
A
DVEN
TM
1
TM
2
TCO
TS
A
TS
B
BAT
A
BAT
B
SNS
A
FCC
B
CH
B
MOD
B
MOD
A

V
CC
V
SS
FCC
A
CH
A
DIS
A
SNS
B
DIS
A
Discharge control output,
battery A
CH
A
, Charge status output,
CH
B
battery A/B
FCC
A
, Fast charge complete output,
FCC
B
battery A/B
V
SS
System ground
V
CC
5.0V ±10% power
MOD
A
, Charge current control
MOD
B
output, battery A/B