Control circuit and method for led drivers
AssigneeRichpower Microelectronics Corporation
InventorsChen-Jie RUAN, Chin-Hui Wang, Liang Mao
Life of this patent
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Abstract
A control circuit and method for a LED driver accurately control the output current of the LED driver by adjusting a reference voltage or a feedback voltage according to the input voltage of the LED driver such that the output current decreases with the decrease of the input voltage. Therefore, it enhances the efficiency of the LED driver and maximizes the battery use time of a battery powered system.
Claims17
A control circuit for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a feedback voltage, the control circuit comprising:
- a reference voltage adjuster connected to a power input terminal of the LED driver, detecting an input voltage of the LED driver and adjusting a first reference voltage accordingly, to thereby generate a second reference voltage;
- and
- an error amplifier connected to the feedback circuit and the reference voltage adjuster, generating an error signal according to a difference between the feedback voltage and the second reference voltage, for controlling the output current.
A control method for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a feedback voltage, the control method comprising the steps of:
- (A) detecting an input voltage of the LED driver and adjusting a first reference voltage accordingly, to thereby generate a second reference voltage;
- and
- (B) generating an error signal according to a difference between the feedback voltage and the second reference voltage, for controlling the output current.
A control circuit for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a first feedback voltage, the control circuit comprising:
- a feedback voltage adjuster connected to the feedback circuit and a power input terminal of the LED driver, detecting an input voltage of the LED driver and adjusting the first feedback voltage accordingly, to thereby generate a second feedback voltage;
- and
- an error amplifier connected to the feedback voltage adjuster, generating an error signal according to a difference between the second feedback voltage and a first reference voltage, for controlling the output current.
A control method for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a first feedback voltage, the control method comprising the steps of:
- (A) detecting an input voltage of the LED driver and adjusting the first feedback voltage accordingly, to thereby generate a second feedback voltage;
- and
- (B) generating an error signal according to a difference between the second feedback voltage and a first reference voltage, for controlling the output current.
A control circuit for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a first feedback voltage, the control circuit comprising:
- a reference voltage adjuster connected to a power input terminal of the LED driver, detecting an input voltage of the LED driver and adjusting a first reference voltage accordingly, to thereby generate a second reference voltage;
- and
- a feedback voltage adjuster connected to the feedback circuit and a power input terminal of the LED driver, detecting the input voltage and adjusting the first feedback voltage accordingly, to thereby generate a second feedback voltage;
- and
- an error amplifier connected to the reference voltage adjuster and the feedback voltage adjuster, generating an error signal according to a difference between the second feedback voltage and the second reference voltage, for controlling the output current.
A control method for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a first feedback voltage, the control method comprising the steps of:
- (A) detecting an input voltage of the LED driver and adjusting a first reference voltage accordingly, to thereby generate a second reference voltage;
- (B) detecting the input voltage and adjusting the first feedback voltage accordingly, to thereby generate a second feedback voltage;
- and
- (C) generating an error signal according to a difference between the second feedback voltage and the second reference voltage, for controlling the output current.
Dependencies are inferred from the claim text.