Apparatus and method for safely handling asychronous shutdown of pulsewidth modulated output
First Claim
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1. An apparatus, comprising:
- a first circuit to determine a commencement of a signal transition from a first state to a second state for a pulsed signal and to determine a minimum period after the commencement of the signal transition wherein the first circuit includes a counter to count to a predetermined value to determine the minimum period; and
a second circuit to receive a shutdown signal to initiate shutdown of associated circuitry, said second circuit to delay the shutdown until the minimum period following the commencement of the signal transition has lapsed and to continue the shutdown at least until the pulsed signal has transitioned back to the first state, even if the shutdown signal has terminated.
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Abstract
An apparatus and method for safely handling asynchronous shutdown of pulsewidth modulated output. A shutdown circuit controls asynchronous shutdown of a pulsewidth modulated stage to ensure that pulsewidth modulated signals of less duration than a minimum period does not occur at transition edges of the pulsewidth modulated signal, in which such short pulses may affect the proper operation of output circuitry.
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Citations
19 Claims
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1. An apparatus, comprising:
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a first circuit to determine a commencement of a signal transition from a first state to a second state for a pulsed signal and to determine a minimum period after the commencement of the signal transition wherein the first circuit includes a counter to count to a predetermined value to determine the minimum period; and a second circuit to receive a shutdown signal to initiate shutdown of associated circuitry, said second circuit to delay the shutdown until the minimum period following the commencement of the signal transition has lapsed and to continue the shutdown at least until the pulsed signal has transitioned back to the first state, even if the shutdown signal has terminated. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus, comprising:
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a modulator to generate a pulsewidth modulated signal utilized to drive an output stage; and a shutdown circuit to receive the pulsewidth modulated signal to determine a commencement of a signal transition from a first state to a second state for the pulsewidth modulated signal and to determine a minimum period after the commencement of the signal transition, said shutdown circuit also to receive a shutdown signal to initiate shutdown of the drive to the output stage and to delay the shutdown until the minimum period following the commencement of the signal transition has lapsed and to continue the shutdown at least until the pulsewidth modulated signal has transitioned back to the first state, even if the shutdown signal has terminated; and wherein said shutdown circuit includes a counter to count to a predetermined value to determine the minimum period. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A method to handle asynchronous shutdown, comprising:
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determining a commencement of a signal transition from a first state to a second state for a pulsewidth modulated signal; determining a minimum period after the commencement of the signal transition of the pulsewidth modulated signal wherein the determining of the minimum period is achieved by counting clock pulses to a predetermined count value; detecting an occurrence of a shutdown signal; initiating a shutdown of an output stage in response to the shutdown signal and delaying the shutdown until the minimum period following the commencement of the signal transition has lapsed; and continuing the shutdown at least until the pulsewidth modulated signal has transitioned back to the first state, even if the shutdown signal has terminated. - View Dependent Claims (17, 18, 19)
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Specification