Rechargeable Alkaline Charge/discharge Controller Ic

  The BQ2902 is a low-cost charger for rechargeable alkaline batteries such as Renewal? batteries from Rayovac?. The BQ2902 combines sensitive, fullcharge detection for two rechargeable 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 properly managing the charge and discharge. 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 provided 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 Transistors 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 Pin Names DC CHG BAT1P Charging supply input Battery status output LRTN Battery 1 positive input VSEL BAT1N Battery 1 negative input End-of-discharge voltage select input System load return VSS Battery 2 negative input IC ground VSEL BAT1N BAT1P DC 1 2 3 4 8 7 6 5 CHG VSS VSS LRTN 8-Pin Narrow DIP or SOIC PN290201.eps 5/99 C 1 BQ2902 Pin
Item: BQ2902
File Size : 13 KB
Pages : 12 Pages

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Texas Instruments Incorporated
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