Resistance measurement of a resistor in a bipolar junction transistor (BJT)-based power stage

摘要

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. A resistor may be coupled to the BJT through a switch at the emitter of the BJT. The switch may regulate operation of the BJT by allowing current flow to ground through the resistor. The controller may perform measurements of the resistor to allow higher accuracy determinations of the current through the BJT and thus improve regulation of current to the LED load.

主权项

1. A method, comprising:
measuring a resistance value of a resistor coupled to an emitter of a bipolar junction transistor (BJT) in a power stage; 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, wherein the measured resistance value is used to determine the first time period and the second time period; and repeating the steps of the switching on the control signal and the switching off the control signal to operate the bipolar junction transistor (BJT) to output a desired average current to the load.