TC649 motor overheating protection and drive circuit

 The motor is a heating device, which often causes the coil winding temperature to be too high due to accidents or overloads. Figure 1-9 shows
the TC649 motor overheating protection and drive circuit .
    N TC thermistor RT is closely attached to the motor to detect the temperature of the motor. RT, ZI, and R2 determine the
input . The setting range is generally 1.2~2.6V. This voltage controls the output point of the output terminal K. The duty cycle of the PWM (Pulse
Width Modulation) signal (variation range is 0~100%). For example, at 30C, VIN = 1.9V, the duty cycle is
50qo; at 60qC, VIN = 2, 6V, the duty cycle is 100%; the PWM signal changes the speed of the motor after being driven by VT1.
Pin ⑤ is current detection, used to limit the size of the motor current. The current flowing through the motor or VT1 produces a voltage drop on R6
, which is fed back to pin ⑤ via c5 to control the maximum output current of the motor. ③Pin sets the threshold level for automatic shutdown.
    With proper selection of VT1 and supply voltage, this circuit can drive a fan or a motor with a larger load .