BQ2002ESNTR Datasheet, PDF (6/15 Pages) Texas Instruments – NiCd/NiMH Fast-Charge Management ICs

bq2002E/G
rate, and voltage hold-off period options. Table 1 de-
scribes the states selected by the TM pin. The mid-
level selection input is developed by a resistor di-
vider between VCC and ground that fixes the voltage
on TM at VCC/2 ± 0.5V. See Figure 4.
Charge Status Indication
A fast charge in progress is uniquely indicated when the
LED pin goes low. The LED pin is driven to the high-Z
state for all conditions other than fast charge. Figure 2
outlines the state of the LED pin during charge.
Low-Power Mode
The IC enters a low-power state when VBAT is driven
above the power-down threshold (VPD) where
VPD = VCC - (1V ±0.5V)
Both the CC pin and the LED pin are driven to the
high-Z state. The operating current is reduced to less
than 1µA in this mode. When VBAT returns to a value
below VPD, the IC pulse-trickle charges until the next
new charge cycle begins.
Charge Inhibit
Fast charge and top-off may be inhibited by using the
INH pin. When high, INH suspends all fast charge and
top-off activity and the internal charge timer. INH
freezes the current state of LED until inhibit is removed.
Temperature monitoring is not affected by the INH pin.
During charge inhibit, the bq2002E/G continues to
pulse-trickle charge the battery per the TM selection.
When INH returns low, charge control and the charge
timer resume from the point where INH became active.
6