Digital pulse width modulator with integrated test and control
First Claim
1. 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;
a logic circuit for receiving the first and second pulses and enabling the driver control unit in accordance with the first and second pulses, 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
a built-in test (BIT) circuit for providing BIT input signals corresponding to the first and second pulses to verify correct operation of the PWM circuit including a feed back path from the driver control unit, the driver control unit having a higher level of integration than the PWM circuit, and the BIT input signals providing control of said PWM circuit.
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Accused Products
Abstract
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 including an input section for receiving an N bit digitized input signal to be modulated and 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 receives and compares the digitized input signal and the digitized triangular waveform to produce an output pulse and a dead-time generator unit produces a first pulse and a second pulse from the output pulse produced from the compare unit. The first and second pulses each drives a corresponding one of the switching circuits and the first and second pulses have different transition times relative to each other. A built-in test (BIT) circuit provides BIT input signals corresponding to the first and second pulses to verify correct operation of the PWM circuit including a feed back path from the driver control unit, the driver control unit having a higher level of integration than the PWM circuit, and the BIT input signals providing individual control of each of the PWM signals.
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Citations
15 Claims
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1. 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:
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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; a logic circuit for receiving the first and second pulses and enabling the driver control unit in accordance with the first and second pulses, 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 a built-in test (BIT) circuit for providing BIT input signals corresponding to the first and second pulses to verify correct operation of the PWM circuit including a feed back path from the driver control unit, the driver control unit having a higher level of integration than the PWM circuit, and the BIT input signals providing control of said PWM circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. 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:
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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.
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14. 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:
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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. - View Dependent Claims (15)
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Specification