Bootstrap circuit in DC/DC static converters
First Claim
1. A bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit for overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, the overcharge circuit being coupled between the second non drivable terminal and a reference voltage.
1 Assignment
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Accused Products
Abstract
A bootstrap circuit in DC/DC static converters is provided that includes a power transistor having a first non drivable terminal coupled with a first input voltage and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period. The bootstrap circuit includes a capacitor coupled respectively with the second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor. The bootstrap circuit includes an overcharge circuit arranged between the second non drivable terminal and ground; the overcharge circuit is able to allow overcharging the capacitor during the off time of the power transistor and for a time period lower than the off time.
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Citations
22 Claims
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1. A bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit for overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, the overcharge circuit being coupled between the second non drivable terminal and a reference voltage. - View Dependent Claims (5, 6, 10, 11, 12, 13, 14)
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
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2. A bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit arranged between the second non drivable terminal and a reference voltage, the overcharge circuit being able to allow overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, wherein the overcharge circuit comprises a series coupling of a resistor and a further transistor. - View Dependent Claims (3, 4, 7, 8, 9)
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
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15. A bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit arranged between the second non drivable terminal and a reference voltage, the overcharge circuit being able to allow overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, wherein the converter comprises an inductance connected between the second non drivable terminal of the power transistor and an output terminal of the converter, a freewheeling diode connected between the non drivable terminal of the power transistor and ground which is adapted for demagnetising the inductance during the off time of the power transistor, the time period for overcharging the capacitor occurring after the period time for demagnetising the inductance.
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
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16. A device including at least one bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantial equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit for overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, the overcharge circuit being coupled between the second non drivable terminal and a reference voltage. - View Dependent Claims (17, 18)
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
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19. A device including at least one bootstrap circuit in a DC/DC static converter including a power transistor having a first non drivable terminal coupled with a first input voltage;
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
a capacitor coupled respectively with a second non drivable terminal of the power transistor and with a second input voltage and an input of the driving means so that the voltage between its terminals is substantially equal to the voltage between the second non drivable terminal and the drivable terminal during the off time of the power transistor; and
an overcharge circuit arranged between the second non drivable terminal and a reference voltage, the overcharge circuit being able to allow overcharging the capacitor during the off time of the power transistor for a time period lower than the off time, wherein the overcharge circuit comprises a series coupling of a resistor and a further transistor. - View Dependent Claims (20, 21, 22)
- and driving means connected with a drivable terminal of the power transistor and adapted for determining the on time and the off time of the power transistor for each prefixed switching time period, the bootstrap circuit comprising;
Specification