LM317 integrated circuit charger circuit

Published:2011/7/18 21:19:00 Author:TaoXi | Keyword: integrated, charger circuit | From:SeekIC

The constant current charging circuit which is composed of the three-port voltage stabilizer is as shown in figure 2-21. Because the electric potential difference of the LM317's pin-1 and pin-2 is 1.25V, if we ignore the shunting effects of R3, R1, LED, the potentiometer R2 can adjust the charging current value, the constant current value I=1.25/R2. In actual use, the R2 always uses the 1W resistance. When the R2 is 25Ω/1W, the charging current of the battery is about 50mA. The charging indicator circuit is composed of the resistor R1 and LED, if we choose the appropriate value of R3, when the battery has the required charging voltage, the VT1 will cut off, the LED will turn off. This circuit can charge more than four No.5 nickel-cadmium batteries.



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