BQ2902 Datasheet, PDF (1/12 Pages) Texas Instruments – Rechargeable Alkaline Charge/Discharge Controller IC

bq2902
Rechargeable Alkaline Charge/Discharge
Controller IC
Features
➤ Safely charges two rechargeable
alkaline batteries such as Re-
newal^® from Rayovac^®
➤ Terminates pulsed charge with
maximum voltage limit
➤ Contains LED charge status out-
put
➤ Features a pin-selectable
low-battery cut-off
➤ Pre-charge qualification indicates
fault condition
➤ Available in 8-pin 300-mil DIP or
150-mil SOIC
General Description
The bq2902 is a low-cost charger for
rechargeable alkaline batteries such
as Renewal^® batteries from Rayovac^®.
The bq2902 combines sensitive, full-
charge detection for two recharge-
able alkaline cells, with a low-battery
cut-off for overdischarge protection.
Designed for system integration
into a two-cell system, the bq2902
can improve the service life of the
rechargeable alkaline cells by prop-
erly managing the charge and dis-
charge. The bq2902 requires a
voltage limited current source to
generate the proper charge pulses
for the Renewal^® cell. Each cell is
individually monitored to ensure
full charge without a damaging
overcharge.
Charge completion is indicated
when the average charge rate falls
below approximately 3% of the fast
charge rate. A status output is pro-
vided to indicate charge in progress,
charge complete, or fault indication.
The bq2902 avoids over-depleting
the battery by using the internal
end-of-discharge control circuit.
The bq2902 also eliminates the
external power switching transis-
tors needed to separately charge
individual Renewal cells.
For safety, charging is inhibited if
the per-cell voltage is greater than
3.0V during charge (closed-circuit
voltage), or if the cell voltage is less
than 0.4V (open-circuit voltage).
Pin Connections
VSEL
1
BAT1N
2
BAT1P
3
DC
4
8
CHG
7
VSS
6
VSS
5
LRTN
8-Pin Narrow DIP
or SOIC
PN290201.eps
Pin Names
DC
CHG
BAT1P
BAT1N
Charging supply input
Battery status output
Battery 1 positive input
Battery 1 negative input
VSS
LRTN
VSEL
Battery 2 negative input
IC ground
System load return
End-of-discharge voltage
select input
5/99 C
1