POWER DISSIPATION MONITOR FOR CURRENT SINK FUNCTION OF POWER SWITCHING TRANSISTOR
First Claim
Patent Images
1. A light emitting diode (LED) lamp comprising:
- a switching power converter including;
a magnetic component coupled to an output voltage of a dimmer switch with phase angle switching and coupled to an output of the switching power converter, the output voltage of the dimmer switch received as the input voltage of the switching power converter;
a switch coupled to the magnetic component, current through the magnetic component being generated while the switch is turned on and not being generated while the switch is turned off; and
a controller configured to generate a control signal to turn on or turn off the switch at each switching cycle of the switch;
wherein the controller is configured to operate the switch in a first mode to deliver electrical power to the output of the switching power converter or operate the switch in a second mode causing the switch to function as a current sink;
wherein the controller is configured to estimate power dissipated by the switch during the second mode to determine whether the switch is approaching an unsafe operating condition;
a current regulator coupled to the output of the switching power converter, the current regulator receiving the electrical power delivered by the switching power converter; and
one or more LEDs coupled to an output of the current regulator;
wherein the current regulator regulates current through the one or more LEDs based on a control signal from the controller.
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Abstract
The embodiments disclosed herein describe a method of a power controller for monitoring for unsafe operating conditions of a drive transistor in a switching power converter of a LED lamp system by predicting the power dissipation of the drive transistor based on knowledge of the current through the drive transistor and a continuous observation of the voltage across the drive transistor. When the drive transistor approaches unsafe operating conditions, the power controller turns off the drive transistor.
78 Citations
20 Claims
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1. A light emitting diode (LED) lamp comprising:
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a switching power converter including; a magnetic component coupled to an output voltage of a dimmer switch with phase angle switching and coupled to an output of the switching power converter, the output voltage of the dimmer switch received as the input voltage of the switching power converter; a switch coupled to the magnetic component, current through the magnetic component being generated while the switch is turned on and not being generated while the switch is turned off; and a controller configured to generate a control signal to turn on or turn off the switch at each switching cycle of the switch; wherein the controller is configured to operate the switch in a first mode to deliver electrical power to the output of the switching power converter or operate the switch in a second mode causing the switch to function as a current sink; wherein the controller is configured to estimate power dissipated by the switch during the second mode to determine whether the switch is approaching an unsafe operating condition; a current regulator coupled to the output of the switching power converter, the current regulator receiving the electrical power delivered by the switching power converter; and one or more LEDs coupled to an output of the current regulator; wherein the current regulator regulates current through the one or more LEDs based on a control signal from the controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a controller, a method of controlling a light emitting diode (LED) lamp, the LED lamp comprising a switching power converter including a magnetic component coupled to an output voltage of a dimmer switch with phase angle switching and coupled to an output of the switching power converter, the output voltage of the dimmer switch received as the input voltage of the switching power converter, and a switch coupled to the magnetic component, current through the magnetic component being generated while the switch is turned on and not being generated while the switch is turned off, the LED lamp further including a current regulator coupled to the output of the switching power converter, the current regulator receiving the electrical power delivered by the switching power converter, and one or more LEDs coupled to an output of the current regulator, the method comprising:
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generating a control signal to turn on or turn off the switch at each switching cycle of the switch; operating the switch either in a first mode to deliver electrical power to the output of the switching power converter or operating the switch in a second mode causing the switch to function as a current sink; and estimating power dissipated by the switch during the second mode to determine whether the switch is approaching an unsafe operating condition. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A light emitting diode (LED) lamp comprising:
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a first switch coupled to an output voltage of a dimmer switch with phase angle switching, the output voltage of the dimmer switch received as an input voltage of the LED lamp; a switching power converter including; a magnetic component coupled to the input voltage of the LED lamp and coupled to an output of the switching power converter; a second switch coupled to the magnetic component, current through the magnetic component being generated while the second switch is turned on and not being generated while the second switch is turned off; and a controller configured to generate a control signal to turn on or turn off the second switch at each switching cycle of the second switch; wherein the controller is configured to turn on the first switch to draw current from the dimmer switch; wherein the controller is configured to estimate power dissipated by the first switch when the first switch is turned on; and wherein the controller is configured to determine whether the first switch is approaching an unsafe operating condition based on the estimated power dissipated by the first switch; a current regulator coupled to the output of the switching power converter, the current regulator receiving the electrical power delivered by the switching power converter; and one or more LEDs coupled to an output of the current regulator; wherein the current regulator regulates current through the one or more LEDs based on a control signal from the controller.
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Specification