Digital pulse width modulator with integrated test and control

A pulse width modulator (PWM) circuit for generating pulses to enable a driver control unit to drive a pair of switching circuits for an electric motor comprising:

• a input section for receiving an N bit digitized input signal to be modulated;
• a PWM counter for continuously counting up from zero to a predetermined number and back down to zero, the PWM counter generating a digitized triangular waveform having N bits of resolution corresponding to the predetermined number;
• a compare unit for receiving and comparing the digitized input signal and the digitized triangular waveform to provide an output pulse;
• a dead-time generator unit for producing a first pulse and a second pulse from the output pulse produced from the compare unit, the first and second pulses each driving a corresponding one of the switching circuits, the first and second pulses having different transition times relative to each other;
• and
• means for preventing input signal values corresponding to peak and valley of the triangular waveform from being compared to the triangular waveform.

A pulse width modulator (PWM) circuit for generating pulses to enable a driver control unit to drive a pair of switching circuits for an electric motor comprising:

• an input section for receiving an N bit digitized input signal to be modulated;
• a PWM counter for continuously counting up from zero to a predetermined number and back down to zero, the PWM counter generating a digitized triangular waveform having N bits of resolution corresponding to the predetermined number;
• a compare unit for receiving and comparing the digitized input signal and the digitized triangular waveform to provide an output pulse;
• a dead-time generator unit for producing a first pulse and a second pulse from the output pulse produced from the compare unit, the first and second pulses each driving a corresponding one of the switching circuits, the first and second pulses having different transition times relative to each other;
• a logic circuit for receiving the first and second pulses and enabling the driver control unit in accordance with the first and second pulses, respectively;
• and
• a test control unit for replacing the input signal of the PWM circuit with a test signal to test the PWM circuit, the test control unit comparing actual PWM output pulses generated from the PWM circuit corresponding to the test signal with known output pulses corresponding to the test signal.