Charge pump-based drive circuitry for bipolar junction transistor (BJT)-based power supply
First Claim
1. An apparatus, comprising:
- a bipolar junction transistor (BJT) configured to provide power to a controller powered from a supply voltage, the transistor comprising;
a collector coupled to a high voltage source;
an emitter configured to switch between a first output and a second output, wherein when the emitter is coupled to the first output the BJT returns energy to the supply voltage, and wherein the emitter is coupled to the second output the BJT drives current to a ground, andwherein the high voltage source comprises a high voltage with respect to the ground, the high voltage being greater in magnitude than the supply voltage with respect to the ground; and
a base; and
a base drive circuit coupled to the base and configured to;
receive the supply voltage; and
generate a current to the base.
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Abstract
A bipolar junction transistor (BJT) may be used to generate a supply voltage for operating a controller, such as a lighting controller for a LED-based light bulb. A base of the BJT may receive current generated from the supply voltage to control operation of the BJT. Although the base of the BJT would be at a lower voltage than the emitter, a base drive circuit may be coupled between the emitter and the base of the BJT to increase the voltage. As one example, the base drive circuit may be a charge pump. In another example, the BJT may function as its own charge pump. In yet another example, a positive and a negative base current of the BJT may be independently controlled to regulate an output supply voltage VDD from the BJT.
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Citations
29 Claims
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1. An apparatus, comprising:
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a bipolar junction transistor (BJT) configured to provide power to a controller powered from a supply voltage, the transistor comprising; a collector coupled to a high voltage source; an emitter configured to switch between a first output and a second output, wherein when the emitter is coupled to the first output the BJT returns energy to the supply voltage, and wherein the emitter is coupled to the second output the BJT drives current to a ground, and wherein the high voltage source comprises a high voltage with respect to the ground, the high voltage being greater in magnitude than the supply voltage with respect to the ground; and a base; and a base drive circuit coupled to the base and configured to; receive the supply voltage; and generate a current to the base. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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receiving, at a collector of a bipolar junction transistor (BJT), a high voltage from a high voltage source; driving, from an emitter of the bipolar junction transistor (BJT) in a first mode, current to a supply voltage node from the high voltage source to generate a power supply voltage, and driving, from an emitter of the BJT in a second mode, current to a ground, wherein the high voltage is high with respect to ground, the high voltage being greater in magnitude than the supply voltage with respect to the ground; and generating, in a base drive circuit, a current to the base. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A system, comprising:
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one or more light emitting diodes (LEDs); a line voltage input node configured to receive a high voltage; a controller coupled to the light emitting diodes (LEDs) and configured to regulate energy transfer from the line voltage input node to the one or more light emitting diodes (LEDs), the controller being powered by a power supply voltage; a bipolar junction transistor (BJT) configured to provide power to the controller, the transistor comprising; a collector coupled to the line voltage input node; an emitter configured to switch between a first output and a second output, wherein when the emitter is coupled to the first output the BJT returns energy to a supply voltage to produce the power supply voltage, and wherein when the emitter is coupled to the second output the BJT drives current to the ground, wherein the high voltage is high with respect to the ground, the high voltage being greater in magnitude than the supply voltage with respect to the ground; and a base; and a base drive circuit coupled to the base and configured to; receive the power supply voltage; and generate a current to the base. - View Dependent Claims (29)
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Specification