BQ24401_15 Datasheet, PDF (13/27 Pages) Texas Instruments – Programmable NiCd/NiMH Fast-Charge Management IC

bq24401
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TEMPERATURE
V_TS < V_HTF
V_TS < V_TCO
SLUS497A – SEPTEMBER 2001 – REVISED MARCH 2010
Table 3. Temperature-Monitoring Conditions and Actions (continued)
CONDITION
Hot battery – checked at all times,
except during fast charge
Battery exceeding maximum
allowable temperature – checked at
all times
ACTION
During charge qualification, stops charging
During fast charge, no effect
During top-off, stops charging
During trickle maintenance charge, stops charging
During charge qualification, stops charging
During fast charge, terminates fast charge and stops charging, turns off
LED
During top-off, terminates top-off and stops charging
During trickle maintenance charge, stops charging
Table 4. Summary of NiCd or NiMH Charging Characteristics
PARAMETER
VALUE ⁽¹⁾
Maximum cell voltage (V_MCV)
Minimum pre-charge qualification voltage (V_LBAT)
High-temperature cutoff voltage (V_TCO)
High-temperature fault voltage (V_HTF)
Low-temperature fault voltage (V_LTF)
bq24401 fast-charge maximum time out (MTO)
Fast-charge charging current (I_MAX)
Hold-off period
2V
950 mV
0.225 × V_CC
0.25 × V_CC
0.5 × V_CC
R_MTO × C_MTO × 35,988
0.05/R_SNS
MTO/32
Top-off charging current (optional)
Top-off period (optional)
I_MAX/16
MTO
Trickle-charge frequency
1Hz
Trickle-charge pulse-width
See Figure 5
(1) See the DC Thresholds Specification for details.
Charge Status Display
The charge status is indicated by open-drain output LED. Table 5 summarizes the display output of the bq24401.
A temperature fault or timer expiring changes the charge state immediately (according to Figure 2) and will thus
change the LED status immediately and accordingly.
Table 5. Charge Status Display
bq24401 CHARGE STATE
Charge qualification (including battery conditioning and charge suspended)
Fast charge (current regulation)
Top-off charge
Trickle maintenance charge (after fast charge)
Charge complete
Battery absent
Sleep mode
LED STATUS
1 Hz flash
Low
High impedance
Sleep Mode
The bq24401 features a sleep mode for low power consumption. This mode is enabled when the voltage at the
BAT pin is above the low-power-mode threshold, V_SLP. During sleep mode, the bq24401 shuts down all
unnecessary internal circuits, drives the LED output to high-impedance state, and drives the MOD pin low.
Restoring BAT below the V_MCV threshold initiates the IC and starts a fast-charge cycle. Normally, the bq24401
only enters sleep mode when there is no battery connected on the output and the charger is idling with nothing to
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