Management. BQ2002G Datasheet

BQ2002G Datasheet PDF


Part BQ2002G
Description NiCd/NiMH Fast-Charge Management
Feature bq2002E/G NiCd/NiMH Fast-Charge Management ICs Features ® Fast charge of nickel cadmium or nickel-.
Manufacture UNITRODE
Datasheet
Download BQ2002G Datasheet


bq2002E/G NiCd/NiMH Fast-Charge Management ICs Features ® BQ2002G Datasheet




BQ2002G
bq2002E/G
NiCd/NiMH Fast-Charge Management ICs
Features
® Fast charge of nickel cadmium
or nickel-metal hydride batter-
ies
® Direct LED output displays
charge status
® Fast-charge termination by -V,
maximum voltage, maximum
temperature, and maximum
time
® Internal band-gap voltage ref-
erence
® Optional top-off charge
® Selectable pulse trickle charge
rates
® Low-power mode
® 8-pin 300-mil DIP or 150-mil
SOIC
Pin Connections
General Description
The bq2002E and bq2002G Fast-
Charge ICs are low-cost CMOS bat-
tery-charge controllers providing reli-
able charge termination for both NiCd
and NiMH battery applications. Con-
trolling a current-limited or con-
stant-current supply allows the
bq2002E/G to be the basis for a cost-
effective stand-alone or system-inte-
grated charger. The bq2002E/G inte-
grates fast charge with optional top-off
and pulsed- trickle control in a single
IC for charging one or more NiCd or
NiMH battery cells.
Fast charge is initiated on application
of the charging supply or battery re-
placement. For safety, fast charge is
inhibited if the battery temperature
and voltage are outside configured
limits.
Pin Names
Fast charge is terminated by any of
the following:
n Peak voltage detection (PVD)
n Negative delta voltage (-V)
n Maximum voltage
n Maximum temperature
n Maximum time
After fast charge, the bq2002E/G op-
tionally tops-off and pulse-trickles the
battery per the pre-configured limits.
Fast charge may be inhibited using
the INH pin. The bq2002E/G may
also be placed in low-standby-power
mode to reduce system power con-
sumption.
The bq2002E differs from the
bq2002G only in that a slightly dif-
ferent set of fast-charge and top-off
time limits is available. All differ-
ences between the two ICs are illus-
trated in Table 1.
TM 1
LED 2
BAT 3
VSS 4
8 CC
7 INH
6 VCC
5 TS
TM
LED
BAT
VSS
Timer mode select input
Charging status output
Battery voltage input
System ground
TS Temperature sense input
VCC Supply voltage input
INH Charge inhibit input
CC Charge control output
8-Pin DIP or
Narrow SOIC
PN-200201.eps
bq2002E/G Selection Guide
Part No. LBAT
bq2002E 0.175
VCC
TCO
0.5
VCC
bq2002G 0.175 0.5
VCC
VCC
HTF
0.6
VCC
0.6
VCC
LTF
None
None
-V PVD
Fast Charge
C/2
1C
2C
C/2
1C
2C
tMTO
200
80
40
160
80
40
Top-Off
None
C/16
None
None
C/16
None
Maintenance
C/32
C/32
C/32
C/32
C/32
C/32
SLUS132 - FEBRUARY 1999
1



BQ2002G
bq2002E/G
Pin Descriptions
TM
LED
BAT
VSS
TS
VCC
INH
Timer mode input
A three-level input that controls the settings
for the fast charge safety timer, voltage ter-
mination mode, top-off, pulse-trickle, and
voltage hold-off time.
Charging output status
Open-drain output that indicates the charging
status.
Battery input voltage
The battery voltage sense input. The input to
this pin is created by a high-impedance re-
sistor divider network connected between
the positive and negative terminals of the
battery.
System ground
Temperature sense input
Input for an external battery temperature
monitoring thermistor.
Supply voltage input
5.0V ± 20% power input.
Charge inhibit input
When high, INH suspends the fast charge in
progress. When returned low, the IC re-
sumes operation at the point where initially
suspended.
CC Charge control output
An open-drain output used to control the
charging current to the battery. CC switch-
ing to high impedance (Z) enables charging
current to flow, and low to inhibit charging
current. CC is modulated to provide top-off,
if enabled, and pulse trickle.
Functional Description
Figure 2 shows a state diagram and Figure 3 shows a
block diagram of the bq2002E/G.
Battery Voltage and Temperature
Measurements
Battery voltage and temperature are monitored for
maximum allowable values. The voltage presented on
the battery sense input, BAT, should represent a
single-cell potential for the battery under charge. A
resistor-divider ratio of
RB1 = N - 1
RB2
is recommended to maintain the battery voltage within
the valid range, where N is the number of cells, RB1 is
the resistor connected to the positive battery terminal,
and RB2 is the resistor connected to the negative bat-
tery terminal. See Figure 1.
Note: This resistor-divider network input impedance to
end-to-end should be at least 200kand less than 1 M.
BAT
bq2002E/G
VSS
RB1
RB2
VCC
RT
R3 VCC
TM TS
R4 bq2002E/G
VSS
PACK +
N
T
C
BAT pin connection
Mid-level
setting for TM
Thermistor connection
NTC = negative temperature coefficient thermistor.
Fg2002E/G01.eps
Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration
2






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