Current is a parameter commonly used when we buy or use DC geared motors. This motor has certain requirements for the use of current. When the current is too high, in order to ensure the normal operation of the motor, we usually limit the current of the motor. The purpose of current limiting is to protect the motor and thus the battery and controller. The following describes the current limiting method of DC geared motors.
1. The external inverter bridge is grounded through a resistor Rs for current sampling. The sampling voltage is input to pin 9 and pin 15 to the current detection comparator. A 100mV reference voltage is set at the inverting input of the comparator as a current limit reference.
2. During the rising time of the sawtooth wave of the oscillator, if the current is too large, the comparator will flip, reset the lower Rs trigger, and turn off the drive output to limit the current from increasing. At the ramp-to-saw time, reset the trigger to turn on the drive output.
3. Using this cycle-by-cycle current comparison, the DC geared motor is limited. If the maximum current is allowed to be Imax, the sampling resistor is selected as follows: Rs = 0.1 / Imax. RC low-pass filter can be set before the input of pin 9.
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