Digital method of measuring driver slew rates for reduced test time

A circuit combination for providing digital signals indicative of slew rate rise and fall times of phase signals of H-bridge power drive transistors of a motor of a mass data storage device, comprising:

• a circuit for generating up and down phase control signals to initiate up and down voltage changes in said phase signals;
• a circuit to produce a state change in a phase status output signal when said phase signal is less than a supply voltage;
• and a digital comparison circuit for comparing said phase status output signal and said up and down control signals, and for producing respective rise and fall digital outputs when said up and down phase control signals and said phase status output signal are the same, wherein said respective rise and fall digital outputs have state change timings that indicate rise and fall times of said motor phase signals.

A method for providing digital signals indicative of slew rates of motor phase signals, comprising:

• generating up and down phase control signals to initiate up and down voltage changes in said motor phase signals;
• producing a state change in a phase status output signal when said phase signal is less than a supply voltage;
• and comparing said phase status output signal and said up and down control signals, and producing respective rise and fall digital outputs when said up and down phase control signals and said phase status output signal are the same, wherein said respective rise and fall digital outputs have state change timings that indicate rise and fall times of said motor phase signals.