bq2005
Fast-Charge IC
for Dual-Battery Packs
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:
n
➤
➤
➤
➤
➤
Rate of temperature rise
(∆T/∆t)
Negative delta voltage (-∆V)
Maximum voltage
Maximum temperature
Maximum time
n
n
n
n
➤
After fast charge, optional top-off
and pulsed current maintenance
phases are available.
Pin Connections
Pin Names
DCMD
A
Discharge command input,
battery A
DVEN
-∆V enable
Timer mode select 1
Timer mode select 2
Temperature cut-off
Temperature sense input,
battery A/B
Battery voltage input,
battery A/B
Sense resistor input ,
battery A/B
DIS
A
CH
A
,
CH
B
FCC
A
,
FCC
B
V
SS
V
CC
MOD
A
,
MOD
B
Discharge control output,
battery A
Charge status output,
battery A/B
Fast charge complete output,
battery A/B
System ground
5.0V
±
10% power
Charge current control
output, battery A/B
DCMDA
DVEN
TM1
TM2
TCO
TSA
TSB
BATA
BATB
SNSA
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
FCCB
CHB
MODB
MODA
VCC
VSS
FCCA
CHA
DISA
SNSB
TM
1
TM
2
TCO
TS
A
,
TS
B
BAT
A
,
BAT
B
SNSA,
SNSB
20-Pin DIP or SOIC
PN200501.eps
SLUS079–JUNE 1999 F
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