Switch-mode drive sensing of reverse recovery in bipolar junction transistor (bjt)-based power converters
AssigneeCirrus Logic, Inc.
InventorsJohn L. Melanson, Ramin Zanbaghi, Thirumalai Rengachari, Prashanth Drakshapalli, Rahul Singh, Arnab Kumar Dutta
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Abstract
A bipolar junction transistor (BJT) may be used in a power stage DC-to-DC converter, such as a converter in LED-based light bulbs. The power stage may be operated by a controller to maintain a desired current output to the LED load. The controller may operate the power stage by monitoring a start and end of a reverse recovery time of the BJT. Information regarding the start and end of the reverse recovery time may be used in the control of the power stage to improve efficiency of the power stage.
Claims24
A method, comprising:
- driving a base current from a base current source to a base of a bipolar junction transistor (BJT) to maintain conduction of the bipolar junction transistor (BJT) during a first time period;
- disconnecting the base current source from the bipolar junction transistor (BJT) for a second time period, wherein the second time period comprises a reverse recovery time period during which the bipolar junction transistor (BJT) remains conducting while the base current source is disconnected;
- and
- detecting an end of the reverse recovery time period by monitoring a voltage at the base of the bipolar junction transistor (BJT).
An apparatus, comprising:
- a controller configured to couple to a base of a bipolar junction transistor (BJT);
- wherein the controller is configured to perform the steps comprising:
- driving a base current from a base current source to the base of the bipolar junction transistor (BJT) to maintain conduction of the bipolar junction transistor (BJT) during a first time period;
- disconnecting the base current source from the bipolar junction transistor (BJT) for a second time period, wherein the second time period comprises a reverse recovery time period during which the bipolar junction transistor (BJT) remains conducting while the base current source is disconnected;
- and
- detecting an end of the reverse recovery time period by monitoring a voltage at the base of the bipolar junction transistor (BJT).
Dependencies are inferred from the claim text.