Power converter, LED driver and control method
AssigneeSilergy Semiconductor Technology (Hangzhou) LTD
InventorsQiukai Huang, Jianxin Wang, Qingliang Zheng
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Abstract
A power converter for an LED drive circuit, can include: a capacitor and an LED load coupled in parallel to receive an output signal of a rectifier circuit; a power switch coupled in series with the LED load, and being configured to control a current path from the rectifier circuit to the LED load; and a control circuit configured to control the power switch to be turned off in accordance with an error between an output current flowing through the LED load and a desired current value to decrease power consumption of the power switch, where the operation of the power switch is controlled to transition between on and off states in each sinusoidal half-wave period.
Claims20
A power converter for a light-emitting diode (LED) drive circuit, the power converter comprising:
- a) a capacitor and an LED load coupled in parallel to receive an output signal of a rectifier circuit;
- b) a power switch coupled in series with said LED load, and being configured to control a current path from said rectifier circuit to said LED load;
- and
- c) a control circuit configured to control said power switch to be turned off for a first time duration in accordance with an error between an output current flowing through said LED load and a desired current value to decrease power consumption of said power switch, wherein the operation of said power switch is controlled to transition between on and off states in each sinusoidal half-wave period.
A method of controlling a power converter having a power switch coupled in series with an light-emitting diode (LED) load for controlling a current path from an input terminal of said power converter to said LED load, the method comprising:
- a) obtaining a sampling voltage representing a voltage difference between the input voltage and the output voltage;
- b) determining a first time duration;
- and
- c) controlling said power switch to be turned off for said first time duration such that an input current concentrates in a time period during which a voltage difference at two power terminals of said power switch is less than a predetermined value and an output current flowing through said LED load remains substantially constant.
Dependencies are inferred from the claim text.