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US 7,583,034 B2Granted
LED controller and method therefor
AssigneeSemiconductor Components Industries, LLC
InventorsAlejandro Lara-Ascorra, Stephen P. Robb, Alan R. Ball
Life of this patent
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Abstract
In one embodiment, a vertical N-channel transistor is coupled in a high side configuration to control a current through an LED. A control circuit operates the vertical N-channel transistor to control a value of the current.
Claims20
An LED controller comprising:
- a vertical N-channel transistor having a gate, having a drain coupled to receive an input voltage, and having a source coupled to supply a load current to an LED;
- and
- a control circuit operably coupled to supply a control voltage to the gate of the vertical N-channel transistor that is representative of a difference between the load current and a desired value of the load current wherein the control voltage is no greater than a voltage on the drain.
A method of forming an LED controller comprising:
- configuring vertical N-channel transistor to receive a power supply voltage on a drain of the vertical N-channel transistor and supply a load current to an LED through a source of the vertical N-channel transistor wherein a gate of the vertical N-channel transistor receives a control voltage that operates the vertical N-channel transistor in a saturated region of the operating characteristics of the vertical N-channel transistor;
- and
- configuring a control circuit to form the control voltage without using a charge pump circuit.
A method of forming an LED controller comprising:
- forming a vertical N-channel transistor on a semiconductor substrate;
- coupling the vertical N-channel transistor to receive an input voltage and form a load current for an LED;
- and
- configuring a control circuit to operate the vertical N-channel transistor in saturation to control a value of the load current.
1 more element
Dependencies are inferred from the claim text.