Motor control circuit and method
In accordance with an embodiment, a method for driving a motor includes generating a position indicator signal in response to a signal from the at least one Hall sensor, wherein the position indicator signal has a first period. A phase shift value is generated using the position indicator signal. The position indicator signal is used to generate an adjusted position indicator signal in response to the phase shift value. In accordance with another embodiment, a lead angle adjustment circuit includes a counter coupled to a subtractor circuit through a multiplier circuit. A storage register is coupled to the output of the counter and to an input of a slope determination circuit, wherein the slope determination circuit is coupled to a first external pin of the lead angle adjustment circuit. A multiplier circuit is coupled to the slope determination circuit and to a second external pin.
1. A method for driving a motor, comprising:
providing a motor having a stator, a rotor, a plurality of coils coupled to the stator, and at least one Hall sensor coupled to the stator;
generating a position indicator signal in response to a signal from the at least one Hall sensor, wherein the position indicator signal has a first period;
generating a phase shift value using the position indicator signal; and
adjusting the position indicator signal to generate an adjusted position indicator signal in response to the phase shift value, wherein generating the adjusted position indicator signal comprises:
determining a number of times the position indicator signal transitions from a first level to a second level before a difference between a first edge of the position indicator signal and a corresponding first edge of the adjusted position indicator signal stabilize to form a first count value;
multiplying the first count value with a predetermined number to generate a multiplied count value; and
using the multiplied count value to determine an amount to advance the adjusted position indicator signal.
2. The method of claim 1 , further including generating a drive voltage from the adjusted position indicator signal.
3. The method of claim 1 , further including:
selecting a count adjustment value from a count adjustment value storage register;
using the count adjustment value and a first control signal coupled to a first external pin to determine a slope of a first count adjustment parameter; and
using the first count adjustment parameter and a second control signal from a second external pin to determine a second count adjustment parameter.
4. The method of claim 3 , further including combining the second count adjustment value with an advance angle control signal to generate a correction factor.
5. The method of claim 4 , wherein using the multiplied count value to determine an amount to advance the adjusted position indicator signal includes combining the multiplied count value with the correction factor to generate the adjusted position indicator signal.
6. The method of claim 5 , further including generating the advance angle signal by:
determining a number of times the position indicator signal transitions from the first level to the second level; and
generating a start signal in response to the number of times the position indicator signal transitions from the first level to the second level.