Abstract: A control chip, a control system, and a control method for a motor are disclosed. The control chip comprises: an analog comparator comprising a first input terminal and a second input terminal, wherein the first input terminal receives a reference voltage of the motor, the second input terminal receives at least one back EMF (Electromotive Force) of the motor in turn, the analog comparator compares each of the at least one back EMF with the reference voltage in turn through a polling method, so as to produce at least one comparison result and control the motor according to the at least one comparison result. Thereby, the analog comparator is able to compare back EMF with the reference voltage without three comparators, and the cost is therefore saved.