Ni-Cd charger circuit with pre-discharge for RC mode - Power Circuit - Circuit Diagram

1. The battery state is operated by many different circuit modules in the charging state and the discharging state, and the battery voltage difference is large in the two states. Therefore, in order to improve the detection efficiency and accuracy, two channels (VB and VB2) are used to detect the battery. Voltage.
2. 14 feet is the key to control the opening (discharging) or off of the load (motor). If the 14 pin is pulled down by the external button, and the IC internally determines by the logic circuit that the battery has enough power to push the motor, the IC will The output of the 18-pin is pulled low, thereby controlling the conduction of the Q2 tube, turning on the motor and the battery, and the motor is powered. During operation, the IC continuously judges the battery voltage through the VB2 pin. If the battery voltage drops to the voltage divided by R5/R4/R3, the voltage on the VB2 pin is lower than 1.65V (related to Vee, the set value is 0.825*Vee). , the 7-second low-voltage indicator LED (3 feet) is lit, and the same is lit for 7 seconds each time the motor is turned off. If you continue to use the battery voltage to drop to 0.80*Vee, the IC will automatically control the 18-pin off motor to protect the battery from over-discharge.
3. In addition to judging the -DV characteristic during the charging process, the IC also detects other states of the battery, and achieves perfect protection measures such as maximum charging voltage protection, maximum charging time protection, and battery body temperature overrun protection.
4. The circuit described above has perfect over-discharge protection, but for Ni-Cd batteries, not only reliable charging protection and discharge protection are required, but also because there is a significant memory effect, and if the battery is not fully charged before charging If the battery is discharged, the battery capacity will become smaller and smaller over time. Therefore, it is hoped that the charger can automatically charge the residual power in the Ni-Cd battery before each charge. Please see the next section: