LED driver and LED driving method
AssigneeSilergy Semiconductor Technology (Hangzhou) LTD
InventorsXiaodong Huang, Jin Jin
Life of this patent
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Abstract
A method of driving an LED can include: (i) controlling a main power switch by a control circuit of an LED driver; (ii) turning on an auxiliary power switch when the main power switch is turned on such that a DC bus voltage is provided to the main power switch through the auxiliary power switch, and the main power switch outputs a driving current to a load; (iii) charging a capacitor by the DC bus voltage through the auxiliary power switch when the main power switch is turned off, where the capacitor is charged until a voltage across the capacitor reaches a predetermined stable voltage; (iv) clamping the voltage across the capacitor at the predetermined stable voltage; and (v) using the clamping voltage across the capacitor as a supply voltage for the control circuit.
Claims20
A method of driving a light-emitting diode (LED) load, the method comprising:
- a) controlling a main power switch by a control circuit of an LED driver, wherein said main power switch, an auxiliary power switch and said LED load are coupled in series between two terminals of a DC bus voltage, and wherein said main power switch is directly connected to said LED load through only an output current sampling resistor;
- b) generating a driving current through said main power switch to drive said LED load when said main power switch and said auxiliary power switch are both on;
- c) controlling said main power switch to turn off in response to said driving current becoming saturated;
- and
- d) charging a capacitor through said auxiliary power switch when said main power switch is off and said auxiliary power switch is on.
A light-emitting diode (LED) driver, comprising:
- a) a main power switch, an auxiliary power switch, and an LED load coupled in series between two terminals of a DC bus voltage, wherein said main power switch is directly connected to said LED load through only an output current sampling resistor;
- b) a control circuit configured to control said main power switch to generate a driving current through said main power switch to drive said LED load when said main power switch and said auxiliary power switch are both on;
- and
- c) said control circuit being configured to control said main power switch to turn off in response to said driving current becoming saturated;
- and
- d) a capacitor configured to be charged through said auxiliary power switch when said main power switch is off and said auxiliary power switch is on.
Dependencies are inferred from the claim text.