BQ2406X Datasheet, PDF (22/31 Pages) Texas Instruments – 1A SINGLE-CHIP Li-Ion/Li-Pol CHARGE MANAGEMENT IC WITH THERMAL REGULATION

bq2406x
SLUS689 – JUNE 2006
www.ti.com
SHORT CIRCUIT PROTECTION
The internal comparators monitor the battery voltage and detect when a short circuit is applied to the battery
terminal. If the voltage at the BAT pin is less than the internal threshold V(scind) (1.8 V typical), the STAT pins
indicate a fault condition (STAT1 = STAT2 = Hi-Z). When the voltage at the BAT pin falls below a second
internal threshold V(sc) (1.4 V typical), the charger power stage is turned off. A recovery current, I(short) (22 mA
typical), is applied to the BAT pin, enabling detection of the short circuit removal. The battery output current
versus battery voltage is shown in the graph, Figure 11
1200
1000
R_ISET at 840 W
800
600
400
200
0
4 3.5 3 2.5 2 1.5 1 0.5 0
Battery Voltage - V
Figure 11. bq2406x Short Circuit Behavior
See the application section for additional details on start-up operation with V(BAT) < V_(SC).
STARTUP WITH DEEPLY DEPLETED BATTERY CONNECTED
The bq2406x charger furnishes the programmed charge current if a battery is detected. If no battery is
connected the bq2406x operates as follows:
• The output current is limited to 22 mA (typ), if the voltage at BAT pin is below the short circuit detection
threshold V_(SC), 1.8 V typical.
• The output current is regulated to the programmed pre-charge current if V_(SC) < V(BAT) < V_(LOWV).
• The output current is regulated to the programmed fast charge current If V(BAT) > V_(LOWV) AND voltage
regulation is not reached.
The output voltage collapses if no battery is present and the end equipment requires a bias current larger that
the available charge current.
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