Controlling output voltage to achieve ultra-low standby power in dim-to-off led applications
AssigneesDialog Semiconductor GmbH, Dialog Semiconductor (UK) Limited
InventorsZhiqiu Ye, Xiaolin Gao, Nailong Wang, Guanglai Deng, Yichuan Niu
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Abstract
An electronic that includes an integrated circuit (IC) configured to regulate an output voltage for powering a light emitting diode (LED). A first transistor is configured to be switched on or off by the IC to inductively couple or decouple a main power supply bus voltage from a primary winding of a transformer to a secondary winding of the transformer connectable to the LED. A second transistor is coupled between the IC and the main power supply bus voltage, and configured to be switched on or off by the IC to selectively provide an IC power supply input voltage to the IC.
Claims10
A flyback converter for powering an LED, comprising:
- a power switch transistor coupled to a primary winding of a transformer;
- a controller configured to control a switching of the power switch transistor to regulate a an output power to the LED during a lighting mode in which an output voltage to the LED is greater than an LED threshold voltage, and wherein the controller is further configured to regulate a light-off output voltage to the LED during a light-off state in which the output voltage to the LED is less than the LED threshold voltage, the controller including a controller power supply voltage input node for a controller power supply voltage coupled to an auxiliary winding of the transformer through a diode;
- and
- a power supply transistor coupled between the power supply voltage input node and an input voltage bus coupled to the primary winding;
- wherein the controller is configured to cycle the power supply transistor during a transition period to the light-off state to maintain the controller power supply voltage above an undervoltage-lockout (UVLO) voltage for the controller.
A flyback converter for powering an LED, comprising:
- a power switch transistor coupled to a primary winding of a transformer;
- a controller configured to control a switching of the power switch transistor to regulate a an output power to the LED during a lighting mode in which an output voltage to the LED is greater than an LED threshold voltage, and wherein the controller is further configured to control the switching of the power switch transistor to regulate a controller power supply voltage for the controller to maintain the controller power supply voltage to be greater than an undervoltage-lockout (UVLO) voltage for the controller during a light-off state in which the output voltage to the LED is less than the LED threshold voltage.
Dependencies are inferred from the claim text.