Patent ID: 9661711
Date: 2017-05-23
CPC Classifications: H05B

Claim:
1. A light emitting diode (LED) system comprising: an LED driver comprising an input pin and a first transistor including a drain node and a source node, wherein the drain node of the first transistor is connected to the input pin of the LED driver; one or more LEDs; a second transistor, external to the LED driver and including a drain node and a source node, wherein current flowing through the one or more LEDs flows through the second transistor when the second transistor is turned on and into the input pin of the LED driver, wherein the source node of the second transistor is connected to the input pin of the LED driver and the drain node of the first transistor; a first capacitor connected to the drain node of the second transistor and the source node of the second transistor to couple changes in a voltage at the drain node of the second transistor to the source node of the second transistor for charging a power supply of the LED driver during normal operation mode, for determining whether the voltage at the drain node of the second transistor is beginning to oscillate, and for determining whether the current flowing through the one or more LEDs has reached an amplitude of zero; and a controller configured to determine whether the voltage at the drain node of the second transistor is beginning to oscillate based on a voltage at the input pin that receives the current flowing through the one or more LEDs into the LED driver, and to determine whether the current flowing through the one or LEDs has reached the amplitude of zero based on the voltage at the same input pin that receives the current flowing through the one or more LEDs into the LED driver, wherein the LED driver further comprises: wherein the controller is configured to determine whether the voltage at the drain node of the second transistor is beginning to oscillate based on the coupled voltage at the internal node, and determine whether the current flowing through the one or more LEDs has reached the amplitude of zero based on the coupled voltage at the internal node.