Generating a voltage feedback signal in non-isolated LED drivers

摘要

An LED lamp comprises one or more LEDs, an inductive element coupled to an input voltage source and the one or more LEDs, and a switch coupled to the inductive element. A first current detector is coupled between the input voltage source and a ground node of the LED lamp, such that a current detected by the first current detector is proportional to a bulk voltage across the input voltage source. A second current detector is coupled between the inductive element and the ground node, such that current detected by the second current detector is proportional to a drain voltage across the switch. A switch controller controls the switch based on a feedback signal indicative of a voltage across the inductive element, which is generated based on a difference between the current detected by the second current detector and the current detected by the first current detector.

主权项

1. A light-emitting diode (LED) lamp, comprising:
one or more LEDs; an inductor coupled to an input voltage source and the one or more LEDs; a switch coupled to the inductor, current in the inductor being generated responsive to the switch being turned on and not generated responsive to the switch being turned off; a first current detector coupled between the input voltage source and a ground node of the LED lamp, the first current detector detecting a current that is proportional to a bulk voltage across the input voltage source; a second current detector coupled between the inductor and the ground node, the second current detector detecting a current that is proportional to a drain voltage across the switch; a current-to-voltage converter configured to:
convert a difference between the current detected by the first current detector and the current detected by the second current detector to a voltage signal based on a resistance of the first current detector and a resistance of the second current detector, andgenerate a feedback signal proportional to a regulated output voltage from the LED lamp based on the voltage signal; and a switch controller receiving the feedback signal and controlling switching of the switch based on the feedback signal to regulate an output current through the one or more LEDs.