SYSTEM AND METHOD FOR PRE-CHARGING A BOOT CAPACITOR IN A SWITCHING REGULATOR WITH HIGH PRE-BIAS VOLTAGE
First Claim
1. An apparatus, comprising:
- a voltage regulator including an high side switching transistor and a low side switching transistor;
an high side driver for controlling operation of the high side switching transistor;
a low side driver for controlling operation of the low side switching transistor;
a bootstrap capacitor for providing an operating voltage to the high side driver, the bootstrap capacitor charged to a predetermined level responsive to a supply voltage; and
wherein the low side driver drives the low side switching transistor according to a process that charges the bootstrap capacitor to the predetermined level, the process turning on the low side switching transistor for a first predetermined number of cycles and turning off the low side switching transistor for a second predetermined number of cycles and repeating the process for predetermined number of times during startup of the voltage regulator when a prebias load is applied to the voltage regulator.
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Accused Products
Abstract
An apparatus comprises a voltage regulator including an high side switching transistor and a low side switching transistor. An high side drive controls operation of the high side switching transistor. A low side driver controls operation of the low side switching transistor. A bootstrap capacitor provides an operating voltage to the high side switching driver. The bootstrap capacitor is charged to a predetermined level responsive to a supply voltage. A low side driver drives the low side switching transistor according to a process that charges the bootstrap capacitor to the predetermined level. The process turns on the low side switching transistor for a first predetermined number of cycles and turns off the low side switching transistor for a second predetermined number of cycles. The process is repeated for a predetermined number of times during startup of the voltage regulator when a prebias load is applied to the voltage regulator.
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Citations
18 Claims
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1. An apparatus, comprising:
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a voltage regulator including an high side switching transistor and a low side switching transistor; an high side driver for controlling operation of the high side switching transistor; a low side driver for controlling operation of the low side switching transistor; a bootstrap capacitor for providing an operating voltage to the high side driver, the bootstrap capacitor charged to a predetermined level responsive to a supply voltage; and wherein the low side driver drives the low side switching transistor according to a process that charges the bootstrap capacitor to the predetermined level, the process turning on the low side switching transistor for a first predetermined number of cycles and turning off the low side switching transistor for a second predetermined number of cycles and repeating the process for predetermined number of times during startup of the voltage regulator when a prebias load is applied to the voltage regulator. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus, comprising:
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a voltage regulator including high side switching circuitry, low side switching circuitry and a bootstrap capacitor for providing an operating voltage to the high side switching circuitry; and wherein the voltage regular includes a startup mode of operation to charge the bootstrap capacitor to a predetermined level by turning on the low side switching circuitry for a first predetermined number of cycles and turning off the low side switching circuitry for a second predetermined number of cycles and repeating the process of turning on and off the low side switching circuitry for a predetermined number of times during startup of the voltage regulator when a prebias load is applied to the voltage regulator. - View Dependent Claims (9, 10, 11, 12)
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13. A method for charging a bootstrap capacitor in a voltage regulator, comprising the steps of:
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a) initiating a startup process for the voltage regulator when a prebias load is applied to the voltage regulator; b) turning on a lower switching transistor for a first predetermined number of clock cycles; c) turning off the lower switching transistor for a second predetermined number of clock cycles; d) repeating steps b)-c) for a predetermined number of times to charge the bootstrap capacitor to a predetermined voltage level while maintaining a negative inductor current in a predetermined range. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification