What is the state of the LM629 PWM magnitude output during power up and reset?
During power-up, before the power supply is valid (5V +/- 10%), there is a chance the PWM output will go high. Some customers have complained about this because it can cause an uncontrolled spin of the motor. Once the LM629 has a valid power supply, it gains control of the PWM output and pulls it low. The motor will then stop due to loading and friction. At this point, the control loop is open and there is no signal to cause the motor to move.