Light emitting diode driving circuit
AssigneeDongbu HiTek Co., Ltd.
InventorSung-Man Pang
Life of this patent
Estimating the term…
Abstract
A LED driving circuit that may control current flow into an LED on a current path according to the amount of light sensed from the LED. An LED driving circuit for driving at least one LED may include at least one of: An optical sensor for receiving light emitted from the LED and generating a feedback signal having a level corresponding to an amount of the received light. A current regulator provided on a path through which current of the LED flows for regulating an amount of current flowing into the LED according to a comparison of the feedback signal with a first reference signal.
Claims16
An apparatus comprising a light emitting diode (LED) driving circuit configured to drive at least one LED, wherein the circuit comprises:
- an optical sensor configured to receive light emitted from said at least one LED and generate a feedback signal corresponding to an amount of light received by the optical sensor;
- and
- a current regulator configured to regulate an amount of current flowing into said at least one LED according to a comparison of the feedback signal with a first reference signal,
- wherein the current regulator comprises:
- a first reference signal generator configured to generate the first reference signal,
- a comparator configured to compare a level of the feedback signal with a level of the first reference signal;
- a first transistor connected between a negative electrode of said at least one LED and a reference voltage source, where the first transistor is driven in response to the comparison of the feedback signal with the first reference signal;
- and
- a first load connected between the first transistor and the reference voltage source,
- wherein the first reference signal generator comprises:
- an operational amplifier comprising a positive input terminal configured to receive a second reference signal;
- a second load connected between a negative input terminal of the operational amplifier and the reference voltage source;
- a second transistor configured to supply a reference current to the second load in response to an output of the operational amplifier;
- a current mirror configured to generate a mirror current of the reference current;
- and
- a first resistor, wherein the mirror current flows into the first resistor and wherein the first reference signal corresponds to a voltage across both ends of the first resistor.
An apparatus comprising light emitting diode (LED) driving circuit configured to drive at least one LED, wherein the circuit comprises:
- an optical sensor configured to receive light emitted from said at least one LED and generate a feedback signal corresponding to an amount of light received by the optical sensor;
- and
- a current regulator configured to regulate an amount of current flowing into said at least one LED according to a comparison of the feedback signal with a first reference signal,
- wherein the current regulator comprises:
- a comparator configured to compare the feedback signal with the first reference signal;
- a reference signal generator configured to generate a second reference signal in response to the comparison of the feedback signal with the first reference signal;
- an operational amplifier comprising a positive input terminal connected to the reference signal generator;
- a first transistor connected between a negative electrode of said at least one LED and a reference voltage source, wherein the first transistor is driven by an output of the operational amplifier;
- and
- a load connected between a negative input terminal of the operational amplifier and the reference voltage source, wherein reference signal generator comprises:
- a second transistor through which a reference current flows, wherein the second transistor is driven in response to the comparison of the feedback signal with the first reference signal;
- a first resistor connected between the second transistor and the reference voltage source;
- a current mirror configured to generate a mirror current of the reference current;
- and
- a second resistor, wherein the mirror current flows into the second transistor and wherein the second reference signal corresponds to a voltage across both ends of the second resistor.
Dependencies are inferred from the claim text.