Texas Instruments BQ2002CSNTR, BQ2002CSN-SITR, BQ2002CSN-SI, BQ2002CSN, BQ2002CPN-SI Datasheet
...
1
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
➤
Selectable pulse-trickle charge
rates
➤ Low-power mode
➤ 8-pin 300-mil DIP or 150-mil
SOIC
General Description
The bq2002C F ast-Charge IC is a lowcost CMOS battery-charge controller
providing reliable charge termination
for both NiCd and NiMH battery appli
cations. Controlling a current-limited
or constant-current supply allows the
bq2002C to be the basis for a costeffective stand-alone or system-inte
grated charger. The bq2002C inte
grates fast charge with 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
replacement. For safety, fast charge is
inhibited if the battery temperature
and voltage are outside configured
limits.
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 bq2002C pulsetrickles the battery per the preconfigured limits. Fast charge may be
inhibited using the INH pin. The
bq2002C may also be placed in lowstandby-power mode to reduce
system power consumption.
NiCd/NiMH Fast-Charge Management IC
bq2002C
TM Timer mode select input
LED
Charging status output
BAT Battery voltage input
V
SS
System ground
1
PN-200201.eps
8-Pin DIP or
Narrow SOIC
2
3
4
8
7
6
5
TM
LED
BAT
V
SS
CC
INH
V
CC
TS
TS Temperature sense input
V
CC
Supply voltage input
INH Charge inhibit input
CC Charge control output
Pin Connections
Pin Names
9/97 B
Pin Descriptions
TM
Timer mode input
A three-level input that controls the settings
for the fast charge safety timer, voltage ter
mination mode, pulse-trickle, and voltage
hold-off time.
LED
Charging output status
Open-drain output that indicates the charging
status.
BAT
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.
V
SS
System ground
TS
Temperaturesenseinput
Input for an external battery temperature
monitoring thermistor.
V
CC
Supply voltage input
5.0V±20% power input.
INH
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 pulse
trickle.
Functional Description
Figure 2 shows a state diagram and Figure 3 shows a
block diagram of the bq2002C.
Battery Voltageand 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-dividerratioof
RB1
RB2
= N - 1
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
battery terminal. See Figure 1.
Note: This resistor-divider network input impedance to
end-to-end should be at least 200kΩ and less than 1 MΩ.
A ground-referenced negative temperature coefficient
thermistor placed near the battery may be used as a lowcost temperature-to-voltage transducer. The temperature
sense voltage input at TS is developed using a resistorthermistor network between V
CC
and VSS. See Figure 1.
2
bq2002C
Fg2002/C.eps
bq2002C
BAT
V
SS
N
T
C
bq2002C
V
CC
V
CC
PACK +
T
S
V
SS
BAT pin connection Thermistor connection
TM
NTC = negative temperature coefficient thermistor.
RT
R3
R4
RB1
RB2
Mid-level
setting for TM
Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration
3
bq2002C
Chip on
V
CC
4.0V
Battery Voltage
too High?
Battery
Temperature?
Charge
Pending
Fast
LED =
Low
S
D
20
02
C
.e
p
s
Battery Voltage
too Low?
V
BAT
< 2V
V
TS
< V
CC
/2
V
TS
> V
CC
/2
V
BAT
> 0.84V and
V
BAT
< 2V and
V
TS
> V
CC
/2
V
BAT
< 0.84V
0.84V < V
BAT
V
BAT
>
2V
Trickle
LED =
Flash
Trickle
LED = Z
V
BAT
> 2V or
VTS < VCC/2 or
PVD or - V or
Maximum Time Out
V
BAT
> 2V
V
BAT
2V
Figure 2. State Diagram
OSC
TM
CC
LED
V
CC
V
SS
BAT
INH
Clock
Phase
Generator
Timing
Control
Sample
History
A to D
Converter
MCV
Check
Power
Down
TS
Bd2002CEG.eps
Voltage
Reference
Power-On
Reset
TCO
Check
HTF
Check
LBAT
Check
Charge-Control
State Machine
PVD, - V
ALU
Figure 3. Block Diagram
Starting ACharge Cycle
Either of two events starts a charge cycle (see Figure 4):
1.Applicationofpowerto V
CC
or
2. Voltage at the BAT pin falling through the maximum
cell voltage V
MCV
where
V
MCV
= 2V ±5%.
If the battery is within the configured temperature and
voltage limits, the IC begins fast charge. The valid
battery voltage range is V
LBAT<VBAT<VMCV,
where
V
LBAT
= 0.175 ∗ VCC±20%
The valid temperature range is V
TS>VHTF
where
V
HTF
= 0.6 ∗ VCC±5%.
If V
BAT
≤ V
LBAT
or VTS≤ V
HTF
, the IC enters the charge-
pending state. In this state pulse trickle charge is
applied to the battery and the LED flashes until the
voltage and temperature come into the allowed fast
charge range or V
BAT
rises above V
MCV
. Anytime V
BAT
≥ V
MCV
, the IC enters the Charge Complete/Battery
Absent state. In this state the LED is off and trickle
charge is applied to the battery until the next new
charge cycle begins.
Fast charge continues until termination by one or more of
the five possible termination conditions:
n
Peak voltage detection (PVD)
n
Negative delta voltage (-∆V)
n
Maximum voltage
n
Maximum temperature
n
Maximum time
4
Corresponding
Fast-Charge
Rate TM Termination
Typical
Fast-
Charge
Time Limits
(minutes)
Typical PVD
and -∆V
Hold-Off
Time (seconds)
Pulse-
Trickle
Rate
Pulse-
Trickle
Pulse Width
(ms)
Maximum
Synchronized
Sampling
Period
(seconds)
C/2 Mid PVD 160 300 C/32 73 18.7
1C Low PVD 80 150 C/32 37 18.7
2C High -∆V 40 75 C/32 18 9.4
Notes: Typical conditions = 25°C, VCC= 5.0V
Mid = 0.5*V
CC
±0.5V
Tolerance on all timing is ±12%.
Table 1. Fast-Charge Safety Time/Hold-Off Table
bq2002C
TD2002C1.eps
Fast ChargingVCC = 0 Fast Charging
CC Output
LED
Charge initiated by application of power
Charge initiated by battery replacement
Pulse-Trickle
See
Table 1
1s
Figure 4. Charge Cycle Phases
Loading...