CASCODE-TYPE DIMMING SWITCH USING A BIPOLAR JUNCTION TRANSISTOR FOR DRIVING A STRING OF LIGHT EMITTING DIODES

摘要

The invention comprises a dimming switch for use with a string of light emitting diodes (LEDs). The dimming switch comprises a bipolar junction transistor (BJT) driven in a cascode scheme. The dimming switch also comprises circuitry to offset the current that drives the base of the BJT to provide a controlled amount of current to the LEDs when the dimming input signal is high.