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DV2003L1
Datasheet
14 pgs142.53 Kb0

Texas Instruments DV2003L1, DV2003S2, DV2003S1, BQ2003STR, BQ2003S-NTR Datasheet

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1
Features
➤
Fast charge and conditioning of nickel cadmium or nickel-metal hydride batteries
➤
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, maxi­mum voltage, maximum tem­perature, and maximum time
➤ Optional top-off charge
General Description
The bq2003 Fast Charge IC provides comprehensive fast charge control functions together with high-speed switching power control circuitry on a monolithic CMOS device.
Integration of closed-loop current control circuitry allows the bq2003 to be the basis of a cost-effective so
Switch-activated discharge-before­charge allows bq2003-based chargers to support battery conditioning and capacity determination.
High-efficiency power conversion is accomplished using the bq2003 as a hysteretic PWM controller for switch-mode regulation of the charg­ing current. The bq2003 may alterna­tively be used to gate an externally regulated charging current.
Fast charge may begin on applica
tion of the charging supply, replace
ment of the battery, or switch de
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)
n
Negative delta voltage (-∆V)
n
Maximum voltage
n
Maximum temperature
n
Maximum time
After fast charge, an optional top-off phase is available. Constant-cur­rent maintenence charge is provided by an external trickle resistor.
Fast-Charge IC
bq2003
CCMD Charge command/select
DCMD Discharge command
DVEN -∆V enable/disable
TM
1
Timer mode select 1
TM
2
Timer mode select 2
TS Temperature sense
BAT Battery voltage
V
SS
System ground
1
PN200301.eps
16-Pin DIP or SOIC
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CC
DIS
MOD
CHG
TEMP
MCV
TCO
SNS
CCMD
DCMD
DVEN
TM
1
TM
2
TS
BAT
V
SS
SNS Sense resistor input
TCO Temperature cutoff
MCV Maximum voltage
TEMP Temperature status
output
CHG Charging status output
MOD Charge current control
DIS Discharge control
V
CC
5.0V±10% power
Pin Connections
Pin Names
SLUS095A - OCTOBER 1999 I
Pin Descriptions
CCMD, DCMD
Charge initiation and discharge-before­charge control inputs
These two inputs control the conditions that begin a new charge cycle and enable discharge-before-charge. See Table 1.
DVEN
-∆V enable input
This input enales/disables -∆V charge termina
TM
1
–
TM
2
Timer mode inputs
TM
1
and TM2are three-state inputs that con
TS
Temperature sense input
Input, referenced to SNS, for an external thermistor monitoring battery temperature.
BAT
Single-cell voltage input
The battery voltage sense input, referenced to SNS. This is created by a high-impedance resistor divider network connected between the positive and the negative terminals of the battery.
Vss
Ground
SNS
Charging current sense input
SNS controls the switching of MOD based on the voltage across an external sense resistor in the current path of the battery. SNS is the reference potential for the TS and BAT pins. If SNS is connected to V
SS
, MOD switches high at the beginning of charge and low at the end of charge.
TCO
Temperature cutoff threshold input
Input to set maximum allowable battery temperature. If the potential between TS and SNS is less than the voltage at the TCO input, then fast charge or top-off charge is terminated.
MCV
Maximum-Cell-Voltage threshold input
Input to set maximum single-cell equivalent voltage. If the voltage between BAT and SNS is greater than or equal to the voltage at the MCV input, then fast charge or top-off charge is inhibited.
Note: For valid device operation, the voltage level on MCV must not exceed
0.6 ∗ V
CC
.
TEMP
Temperature status output
Push-pull output indicating temperature status. TEMP is low if the voltage at the TS pin is not within the allowed range to start fast charge.
CHG
Charging status output
Push-pull output indicating charging status. See Figure 1.
MOD
Current-switching control output
MOD is a push/pull output that is used to control the charging current to the battery. MOD switches high to enable charging cur
DIS
Discharge FET control output
Push-pull output used to control an external transistor to discharge the battery before charging.
V
CC
VCCsupply input
5.0 V, ±10% power input.
2
bq2003
Functional Description
Figure 3 shows a state diagram and Figure 4 shows a block diagram of the bq2003.
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 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 bat
tery terminal. See Figure 1.
Note: This resistor-divider network input impedance to end-to-end should be at least 200kΩ and less than 1MΩ.
A ground-referenced negative temperature coefficient thermistor placed in proximity to the battery may be used as a low-cost temperature-to-voltage transducer. The tem
perature sense voltage input at TS is developed using a re
sistor-thermistor network between V
CC
and battery’s nega
tive terminal See Figure 1. Both the BAT and TS inputs are referenced to SNS, so the signals used inside the IC are:
V
BAT-VSNS=VCELL
and
V
TS-VSNS=VTEMP
3
Table 1. New Charge Cycle and Discharge Stimulus
CCMD DCMD New Charge Cycle
Started by:
Discharge-Before-Charge
Started by:
Pulled Up/Down to:
V
SS
V
SS
VCCrising to valid level
A rising edge on DCMD
Battery replacement
(V
CELL
falling through V
MCV
A rising edge on CCMD
V
CC
V
CC
VCCrising to valid level
A rising edge on DCMD
Battery replacement
(V
CELL
falling through V
MCV
A falling edge on CCMD or DCMD
V
CC
V
SS
A rising edge on CCMD A rising edge on DCMD
V
SS
V
CC
A falling edge on CCMD A rising edge on DCMD
bq2003
Fg2003a2.eps
N T C
bq2003
V
CC
PACK +
PACK -
T
S
SNS
RT1
RT2
RB2
RB1
bq2003
V
DC
External Trickle Resistor Negative Temperature
Coefficient Thermister
Pass Element
PACK+
PACK-
MOD
BAT
SNS
Figure 1. Voltage and Temperature Monitoring and Trickle Resistor
Discharge-Before-Charge
The DCMD input is used to command discharge-before­charge via the DIS output. Once activated, DIS becomes active (high) until V
CELL
falls below V
EDV,
at which time DIS goes low and a new fast charge cycle begins. See Table 1 for the conditions that initiate discharge-before­charge. Discharge-before-charge is qualified by the same voltage and temperature conditions that qualify a new charge cycle start (see below). If a discharge is ini
Starting A Charge Cycle
The stimulus required to start a new charge cycle is de
1. V
CC
rising above 4.5V
2. V
CELL
falling through the maximum cell voltage,
V
MCV
.V
MCV
is the voltage presented at the MCV input pin, and is configured by the user with a re­sistor divider between V
CC
and ground. The al-
lowed range is 0.2 to 0.4 ∗ V
CC
.
3. A rising edge on CCMD if it is pulled down, or a fal
ling edge on CCMD if it is pulled up.
Starting a new charge cycle may be limited to a push­button or logical pulse input only by pulling one member of the DCMD and CCMD pair up while pulling the other input down. In this configuration a new charge cycle will be started only by a falling edge on CCMD if it is pulled up, and by a falling edge on CCMD if it is pulled down. See Table 1.
If the battery is within the configured temperature and voltage limits, the IC begins fast charge. The valid bat
tery voltage range is V
EDV<VBAT<VMCV
where:
V
EDV
= 0.2 ∗ VCC± 30mV
The valid temperature range is V
HTF<VTEMP<VLTF
,
where:
V
LTF
= 0.4 ∗ VCC± 30mV
V
HTF
= [(1/8 ∗ V
LTF
) + (7/8 ∗ V
TCO
)] ± 30mV
V
TCO
is the voltage presented at the TCO input pin, and is
configured by the user with a resistor divider between V
CC
and ground. The allowed range is 0.2 to 0.4 ∗ VCC.
If the temperature of the battery is out of range, or the voltage is too low, the chip enters the charge pending state and waits for both conditions to fall within their allowed limits. There is no time limit on the charge pending state; the charger remains in this state as long as the voltage or temperature conditons are outside of
4
bq2003
Fast Charging Top-Off
(Optional)
34 sec.
TD200301a.eps
Discharge
(Optional)
Charge
Pending
DIS
MOD Switch-Mode Configuration
MOD External Regulation (SNS Grounded)
CHG Status Output
TEMP Status Output
Charge cycle start. Battery outside temperature limits.
or
Battery within temperature limits.
Battery discharged to 0.2 VCC.
4
sec
.
Figure 2. Charge Cycle Phases
the allowed limits. If the voltage is too high, the chip goes to the battery absent state and waits until a new charge cycle is started.
Fast charge continues until termination by one or more of the five possible termination conditions:
n
Delta temperature/delta time (∆T/∆t)
n Negative delta voltage (-
∆
V)
n
Maximum voltage
n
Maximum temperature
n
Maximum time
-∆V Termination
If the DVEN input is high, the bq2003 samples the volt
age at the BAT pin once every 34s. If V
CELL
is lower than any previously measured value by 12mV ±4mV, fast charge is terminated. The -∆V test is valid in the range V
MCV
- (0.2 ∗ VCC)<V
CELL<VMCV
.
Voltage Sampling
Each sample is an average of 16 voltage measurements taken 57µs apart. The resulting sample period (18.18ms) filters out harmonics around 55Hz. This technique mini
Voltage Termination Hold-off
A hold-off period occurs at the start of fast charging. During the hold-off period, -∆V termination is disabled. This avoids premature termination on the voltage spikes sometimes produced by older batteries when fast-charge current is first applied. ∆T/∆t, maximum voltage and
maximum temperature terminations are not affected by the hold-off period.
∆T/∆t Termination
The bq2003 samples at the voltage at the TS pin every 34s, and compares it to the value measured two samples earlier. If V
TEMP
has fallen 16mV ±4mV or more, fast charge is terminated. The ∆T/∆t termination test is valid only when V
TCO<VTEMP<VLTF
.
Temperature Sampling
Each sample is an average of 16 voltage measurements taken 57µs apart. The resulting sample period (18.18ms) filters out harmonics around 55Hz. This tech
Maximum Voltage, Temperature, and Time
Anytime V
CELL
rises above V
MCV,
CHG goes high (the LED goes off) immediately. If the bq2003 is not in the voltage hold-off period, fast charging ceases if V
CELL
remains above
MCV for a minimum of t
MCV
.IfV
CELL
then falls back be
low V
MCV
before 1.5t
MCV
±50ms, the chip transitions to the Charge Complete state (maximum voltage termination). If V
CELL
remains above V
MCV
beyond 1.5t
MCV
, the bq2003 transitions to the Battery Absent state (battery removal). See Figure 3.
If the bq2003 is in the voltage hold-off period when V
CELL
rises above V
MCV,
the LED goes out but fast charging continues until the expiration of the hold-off period. Temperature sampling continues during the hold-off period as well. If a new battery is inserted be
5
bq2003
Corresponding
Fast-Charge Rate TM1 TM2
Typical Fast Charge
and Top-Off Time Limits
Typical -∆V/MCV
Hold-Off
Time (seconds)
Top-Off
Rate
C/4 Low Low 360 137 Disabled C/2 Float Low 180 820 Disabled
1C High Low 90 410 Disabled 2C Low Float 45 200 Disabled 4C Float Float 23 100 Disabled
C/2 High Float 180 820 C/16
1C Low High 90 410 C/8 2C Float High 45 200 C/4 4C High High 23 100 C/2
Note: Typical conditions = 25°C, VCC= 5.0V.
Table 2. Fast-Charge Safety Time/Hold-Off/Top-Off Table
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