Compensating for a reverse recovery time period of a bipolar junction transistor (BJT) in switch-mode operation of a light-emitting diode (LED)-based bulb
First Claim
1. A method comprising:
- switching on a control signal to operate a bipolar junction transistor (BJT) for a first time period to charge an energy storage device;
switching off the control signal to operate the bipolar junction transistor (BJT) for a second time period to discharge the energy storage device to a load;
repeating the steps of switching on and switching off the bipolar junction transistor (BJT) to output a desired average current to the load; and
dynamically adjusting the repeating of the switching on and the switching off to maintain the desired average current to the load by compensating for a reverse recovery time period of the bipolar junction transistor (BJT).
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Abstract
A turn-off transition time period, also referred to as a reverse recovery time period, may be compensated for by a controller of a power stage including a bipolar junction transistor (BJT). The reverse recovery time period may be measured in one switching cycle and a subsequent switching cycle may include compensations based on the measured reverse recovery time period. That is the switching on and off of the BJT may be compensated to obtain a desired average output current to a load. When the reverse recovery time period is known, an error in the peak current obtained due to the reverse recovery time period may be calculated. The calculated error may be used to offset the target peak current for controlling the switching of the BJT to begin a turn-off transition of the BJT earlier in a switching cycle and thus reduce error in peak current at the BJT.
176 Citations
22 Claims
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1. A method comprising:
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switching on a control signal to operate a bipolar junction transistor (BJT) for a first time period to charge an energy storage device; switching off the control signal to operate the bipolar junction transistor (BJT) for a second time period to discharge the energy storage device to a load; repeating the steps of switching on and switching off the bipolar junction transistor (BJT) to output a desired average current to the load; and dynamically adjusting the repeating of the switching on and the switching off to maintain the desired average current to the load by compensating for a reverse recovery time period of the bipolar junction transistor (BJT). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus, comprising:
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a controller configured to couple to a base and an emitter of a bipolar junction transistor (BJT), wherein the controller is configured to perform the steps comprising; switching on a control signal to operate the bipolar junction transistor (BJT) for a first time period to charge an energy storage device; switching off the control signal to operate the bipolar junction transistor (BJT) for a second time period to discharge the energy storage device to a load; repeating the steps of switching on and switching off the bipolar junction transistor (BJT) to output a desired average current to the load; and dynamically adjusting the repeating of the switching on and the switching off to maintain the desired average current to the load by compensating for a reverse recovery time period of the bipolar junction transistor (BJT). - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification