Led driver and led driving method
AssigneeSilergy Semiconductor Technology (Hangzhou) LTD
InventorsXiaodong Huang, Jin Jin
Life of this patent
Estimating the term…
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 and an auxiliary power switch are coupled in series between a DC bus voltage and said LED load, and wherein said DC bus voltage comprises a sinusoidal half-wave voltage signal;
- f) turning on, by said control circuit, said main power switch when a detection voltage at a common node between said main power switch and said auxiliary power switch is less than a predetermined voltage;
- and
- g) driving, by a driving current output from said main power switch, said LED load when said main power switch and said auxiliary power switch are both on.
A light-emitting diode (LED) driver, comprising:
- a) a main power switch and an auxiliary power switch coupled in series between a DC bus voltage and an LED load;
- b) a control circuit configured to turn on said main power switch when a detection voltage at a common node between said main power switch and said auxiliary power switch is less than a predetermined voltage;
- and
- c) wherein said DC bus voltage comprises a sinusoidal half-wave voltage signal, and a driving current output from said main power switch is configured to drive said LED load when said main power switch and said auxiliary power switch are both on.
The LED driver of claim 18, wherein said supply voltage control circuit comprises:
- a) a first unidirectional conduction circuit having a first terminal coupled to a first terminal of said main power switch, a second terminal coupled to an input terminal of said supply voltage, wherein said first unidirectional conduction circuit is turned on when a voltage at said first terminal of said first unidirectional conduction circuit is higher than a voltage at said second terminal;
- and
- b) a second unidirectional conduction circuit having a first terminal coupled to said input terminal of said supply voltage, a second terminal coupled to a gate of said auxiliary power switch, wherein said second unidirectional conduction circuit is turned on when a voltage at said first terminal of said second unidirectional conduction circuit is higher than a voltage at a second terminal.
Dependencies are inferred from the claim text.