Reflected energy adaptive inductive load driver and method therefor

An inductive load driver comprising:

• a drive transistor with a control input, a sense output, and a drive output, the drive output coupled to and providing current to an inductive load and then preventing the providing of current to the inductive load, wherein the inductive load reflects the previously provided current to the drive transistor when the drive transistor is preventing the providing of current;
• current sensing means coupled to the sense output of the drive transistor for determining the previously provided current reflected by the inductive load, while the drive transistor is preventing the providing of current to the inductive load, and for providing an output indicative of the reflected current;
• current reference means for providing a current reference threshold;
• and
• control means for providing a drive waveform having an on-state and an off-state, the drive waveform coupled to the control input of the drive transistor, wherein a duration of the on-state of the drive waveform is reduced when the current reflected at the output of the current sensing means exceeds the current reference threshold provided by the current reference means.

An adaptive ignition inductive load driver comprising:

• a drive transistor with a control input, a sense output, and a drive output, the drive output coupled to and repetitively providing current to an ignition coil and preventing the providing of current to the ignition coil, wherein the ignition coil reflects the previously provided current to said drive transistor when said drive transistor is preventing the providing of current;
• current sense resistor coupled to the sense output of said drive transistor for determining the current reflected by said ignition coil and for providing an output indicative of said reflected current;
• current reference means for providing a current reference threshold;
• comparison means for comparing the output of said current sense resistor to the current reference threshold provided by said current reference means and providing an output activated when the current provided at the output of said current sense resistor exceeds the current reference threshold provided by said current reference means;
• means for providing an oscillating waveform;
• a logical AND gate having a first input, a second input, and an output, wherein the first input is coupled to said means for providing an oscillating waveform for receiving an oscillating waveform, the second input is coupled to the output of said comparison means, and the output, responsive to the first and second inputs for providing a clock waveform;
• a counter having a clock input and an output, wherein the clock input is coupled to the output of said logical AND gate for receiving the clock waveform and the output, responsive to the clock input, for providing an indication of a time duration that at least a predetermined level of current reflected by said inductive load exceeds the current reference threshold provided by said current reference means;
• and
• control means for providing an essentially periodic drive waveform having an on-state and an off-state, the essentially periodic drive waveform coupled to the control input of said drive transistor, wherein duration of the on-state of the essentially periodic drive waveform is reduced, responsive to a time duration that the current is reflected by said inductive load to said driving means determined at the output of said current sense resistor, exceeds the current reference threshold provided by said current reference means.

An inductive load driver method comprising the steps of:

• metering current to an inductive load, wherein the metering of current is dependent on a relationship between a first logical state of a drive waveform and a second logical state of the drive waveform, wherein the driving means provides current to the inductive load dependent on the first logical state of the drive waveform and prevents the providing of current to the inductive load dependent on the second logical state of the drive waveform;
• measuring the current reflected by the inductive load;
• and
• adjusting the current provided to the inductive load responsive to the step of measuring the current reflected by the inductive load.

An inductive load driver method comprising the steps of:

• providing current to an inductive load and then preventing the providing of current to the inductive load, wherein the inductive load reflects the previously provided current responsive to the step of preventing the providing of current;
• providing a current reference threshold;
• measuring the current reflected by the inductive load;
• comparing the current reflected by the inductive load, measured in the step of measuring, to the current reference threshold and providing an overcurrent waveform;
• comparing a time the overcurrent waveform is provided to a predetermined reference time;
• and
• adjusting the current provided to the inductive load responsive to the step of comparing the time the overcurrent waveform is provided to a predetermined reference time.