US Patent No. 10,602,598

DIMMING CIRCUIT FOR LED LAMP


Patent No. 10,602,598
Issue Date March 24, 2020
Title Dimming Circuit For Led Lamp
Inventorship Ke Wang, Zhejiang (CN)
Assignee Self Electronics Co., Ltd., Ningbo (CN)

Claim of US Patent No. 10,602,598

1. A dimming circuit for an LED lamp, electrically connected to the LED load, comprising:a constant voltage source for supplying power to the LED load;
a switching tube connected in series with the LED load at the output end of the constant voltage source, and a dimming level of the LED load is realized through on and off of the switching tube;
a short circuit detecting circuit, wherein an input end of the short circuit detecting circuit is electrically connected to the constant voltage source for detecting an output voltage of the power supply circuit to obtain a short circuit voltage signal;
a signal processing circuit, wherein an input end of the signal processing circuit is electrically connected to an output end of the short circuit detecting circuit, used for calculating whether or not a short circuit condition occurs, and is capable of timing control detecting a short circuit recovery of the LED load in an event of a short circuit;
a driving circuit electrically connected to an output end of the signal processing circuit and the switching tube, used for driving the switching tube to be turned on or off according to a control signal of the signal processing circuit to perform PWM dimming on the LED load under normal conditions, and driving the switching tube to be turned off for short circuit protection in a case of a short circuit, and driving the switching tube is turned off to achieve short circuit protection, and driving the switching tube to be turned on temporarily to detect a recovery condition when it is necessary to detect an elimination condition of the short circuit of the LED load,
and wherein
the constant voltage source includes a flyback transformer, a power management chip, a first rectifying and filtering circuit, and a second rectifying and filtering circuit;
the flyback transformer includes a first primary coil, a second primary coil, and secondary coil;
one end of the first primary coil is electrically connected to an external power source, and other end of the first primary coil is electrically connected to a control end of the power management chip;
both ends of the secondary coil are electrically connected to the input end of the first rectifying and filtering circuit, and the driving circuit is connected to the output end of the first rectifying and filtering circuit, and an signal input end of the driving circuit is electrically connected to the output end of the signal processing circuit, and an drive output end of the driving circuit is electrically connected to the switching tube;
both ends of the second primary coil are electrically connected to the input end of the second rectifying and filtering circuit;
two power supply ends of the power management chip are respectively electrically connected to the external power source and the output end of the second rectifying and filtering circuit; the input end of the short circuit detecting circuit is connected to the output end of the second rectifying and filtering circuit.