Circuit for driving two power mosfets in a half-bridge configuration
First Claim
1. A circuit for alternately driving first and second transistors, each transistor having a control terminal for receiving a transistor drive signal, at least one of said transistor having a terminal coupled to an output terminal adapted to be coupled to a load and to a bootstrap capacitor charged to provide a boosted drive voltage to the first transistor, said circuit comprising:
- a driver input adapted for receiving a driver input signal having a first state intended to turn the first transistor ON and the second transistor OFF, and a second state intended to turn the first transistor OFF and the second transistor ON;
means for monitoring the first transistor to generate a first signal indicative of the first transistor being in an operational state that can be considered substantially OFF;
means for monitoring the second transistor to generate a second signal indicative of the second transistor being in an operational state that can be considered substantially OFF;
means for monitoring the voltage at the output terminal to generate a recharge signal when the output voltage is below a predetermined voltage level; and
means coupled to the control terminals of the first and second transistors for driving the transistors in response to the driver input signal, the recharge signal and the first and second signals, so that (1) the first transistor is prevented from being driven ON until the driver input signal is in the first state and the second and recharge signals are also present, and (2) the second transistor is prevented from being driven ON until the driver input signal is in the second state and the first signal is also present,whereby the drive to the first transistor is inhibited until the second transistor is considered to be substantially OFF and the bootstrap capacitor has had time to charge sufficiently to provide at least a predetermined boost to the first transistor drive voltage, and the drive to the second transistor is inhibited until the first transistor is considered to be substantially OFF.
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Accused Products
Abstract
A driver circuit for driving top and bottom power transistors stacked between two supply terminals is provided. The driver circuit includes shoot-through reduction means for monitoring the gate-to-source voltages of the two power transistors so as to inhibit the turning-ON of each power transistor until the gate-to-source voltage of the other power transistor has fallen to a voltage level indicative of the other transistor being OFF. Additionally, the driver circuit which can utilize a bootstrap capacitor for providing enhanced voltages to drive the top power transistor, also includes a bootstrap capacitor recharge means to monitor the output voltage of the circuit so as to inhibit the turning-ON of the top power transistor until the bootstrap capacitor has had sufficient time to recharge.
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Citations
22 Claims
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1. A circuit for alternately driving first and second transistors, each transistor having a control terminal for receiving a transistor drive signal, at least one of said transistor having a terminal coupled to an output terminal adapted to be coupled to a load and to a bootstrap capacitor charged to provide a boosted drive voltage to the first transistor, said circuit comprising:
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a driver input adapted for receiving a driver input signal having a first state intended to turn the first transistor ON and the second transistor OFF, and a second state intended to turn the first transistor OFF and the second transistor ON; means for monitoring the first transistor to generate a first signal indicative of the first transistor being in an operational state that can be considered substantially OFF; means for monitoring the second transistor to generate a second signal indicative of the second transistor being in an operational state that can be considered substantially OFF; means for monitoring the voltage at the output terminal to generate a recharge signal when the output voltage is below a predetermined voltage level; and means coupled to the control terminals of the first and second transistors for driving the transistors in response to the driver input signal, the recharge signal and the first and second signals, so that (1) the first transistor is prevented from being driven ON until the driver input signal is in the first state and the second and recharge signals are also present, and (2) the second transistor is prevented from being driven ON until the driver input signal is in the second state and the first signal is also present, whereby the drive to the first transistor is inhibited until the second transistor is considered to be substantially OFF and the bootstrap capacitor has had time to charge sufficiently to provide at least a predetermined boost to the first transistor drive voltage, and the drive to the second transistor is inhibited until the first transistor is considered to be substantially OFF. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 18, 19, 20)
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13. A circuit for alternately driving first and second transistors, each transistor having a control terminal for receiving a transistor drive signal, at least one of said transistors having a terminal coupled to an output terminal adapted to be coupled to a load and to a bootstrap capacitor charged to provide a boosted drive voltage to the first transistor, said circuit adapted for receiving a driver input signal having a first state intended to turn the first transistor ON and the second transistor OFF, and a second state intended to turn the first transistor OFF and the second transistor ON, said circuit comprising:
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means for generating a first signal responsive to a determination that the first transistor has entered an operational state that can be considered substantially OFF; means for generating a second signal responsive to a determination that the second transistor has entered an operational state that can be considered substantially OFF; and means for generating a recharge signal indicative of the bootstrap capacitor having charged sufficiently to provide at least a predetermined boost to the first transistor drive voltage; and means coupled to the control terminals of the first and second transistors for driving the transistors in response to the driver input signal, the recharge signal and the first and second signals, so that (1) the first transistor is prevented from being driven ON until the driver input signal is in the first state and the second and recharge signals are also present, and (2) the second transistor is prevented from being driven ON until the driver input signal is in the second state and the first signal is also present, whereby the drive to the first transistor is inhibited until the second transistor is considered to be substantially OFF and the bootstrap capacitor has had time to sufficiently charge, and the drive to the second transistor is inhibited until the first transistor is considered to be substantially OFF. - View Dependent Claims (21)
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14. A method for alternately driving first and second transistors, each transistor having a control terminal for receiving a transistor drive signal, at least one of said transistors having a terminal coupled to an output terminal adapted to be coupled to a load and to a bootstrap capacitor charged to provide a boosted drive voltage to the first transistor, said circuit adapted for receiving a driver input signal having a first state intended to turn the first transistor ON and the second transistor OFF, and a second state intended to turn the first transistor OFF and the second transistor ON, said method comprising the steps of:
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detecting when the first transistor has entered an operational state that can be considered substantially OFF to responsively generate a first signal; detecting when the second transistor has entered an operational state that can be considered substantially OFF to responsively generate a second signal; and generating a recharge signal indicative of the bootstrap capacitor having charged sufficiently to provide at least a predetermined boost to the first transistor drive voltage; and driving the transistors in response to the driver input signal, the recharge signal and the first and second signals, so that (1) the first transistor is prevented from being driven ON until the driver input signal is in the first state and the second and recharge signals are also present, and (2) the second transistor is prevented from being driven ON until the driver input signal is in the second state and the first signal is also present, whereby the drive to the first transistor is inhibited until the second transistor is considered to be substantially OFF and the bootstrap capacitor has had time to sufficiently charge, and the drive to the second transistor is inhibited until the first transistor is considered to be substantially OFF. - View Dependent Claims (22)
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15. A circuit for alternately driving first and second transistors, each transistor having a control terminal for receiving a transistor drive signal, at least one of said transistors having a terminal coupled to an output terminal adapted to be coupled to a load and to a bootstrap capacitor charged to provide a boosted drive voltage to the first transistor, said circuit comprising:
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a driver input adapted for receiving a driver input signal having a first state intended to turn the first transistor ON and the second transistor OFF, and a second state intended to turn the first transistor OFF and the second transistor ON; means for monitoring one of the first and second transistors to generate an "OFF" signal indicative of the monitored transistor being in an operational state that can be considered substantially OFF; means for generating a recharge signal indicative of the bootstrap capacitor having charged sufficiently to provide at least a predetermined boost to the first transistor drive voltage; and means coupled to the control terminals of the first and second transistors for driving the transistors in response to the driver input signal, and to the "OFF" and recharge signals, so that; (1) if the second transistor is monitored, the first transistor is prevented from being driven ON until the driver input signal is in the first state, and the recharge and "OFF" signals are also present;
or(2) if the first transistor is monitored, (a) the second transistor is prevented from being driven ON until the driver input signal is in the second state and the "OFF" signal is also present, and (b) the first transistor is prevented from being driven ON until the driver input signal is in the first state and the recharge signal is also present, whereby the efficiency of the circuit is improved. - View Dependent Claims (16, 17)
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Specification