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US 7,679,351 B2Granted
Power supply apparatus
AssigneeRohm Co., Ltd.
InventorsHiroaki Asazu, Kunihiro Komiya
Life of this patent
Estimating the term…
Abstract
A voltage generation unit generates a driving voltage for driving an LED. A first feedback path feeds back a voltage according to a voltage at one end of the LED. A second feedback path feeds back a voltage according to a voltage at the other end of the LED. A current driving circuit is provided on a path on which the voltage generation unit drives the LED. A control circuit controls the voltage generation unit so that one of first and second feedback voltages fed back by the first and second feedback paths, respectively is closer to a predetermined reference voltage.
Claims16
A power supply apparatus comprising:
- a voltage generation unit generating a driving voltage for driving a load;
- a first feedback path feeding back a voltage according to a voltage at one end of the load;
- a second feedback path feeding back a voltage according to a voltage at the other end of the load;
- and
- a control circuit controlling the voltage generation unit so that one of a first feedback voltage and a second feedback voltage fed back by the first feedback path and the second feedback path, respectively is closer to a predetermined reference voltage;
- wherein the control circuit includes an error amplifier amplifying an error between one of the first feedback voltage and the second feedback voltage and the reference voltage, and adjusts the driving voltage so that the error is closer to zero, and
- the error amplifier includes two input differential pairs, the reference voltage and the first feedback voltage being input to one of the two input differential pairs, and the reference voltage and the second feedback voltage being input to other input differential pair.
4 more elements
A power supply apparatus comprising:
- a voltage generation unit generating a driving voltage for driving a load;
- a current driving circuit provided on a path on which the voltage generation unit drives the load;
- a first feedback path feeding back a first feedback voltage according to the driving voltage;
- a second feedback path feeding back a second feedback voltage according to a voltage at a connection point between the current driving circuit and the load;
- and
- a control circuit controlling the voltage generation unit so that one of the first feedback voltage and the second feedback voltage fed back by the first feedback path and the second feedback path, respectively is closer to a predetermined reference voltage;
- wherein the control circuit includes an error amplifier amplifying an error between one of the first feedback voltage and the second feedback voltage and the reference voltage, and adjusts the driving voltage so that the error is closer to zero, and
- the error amplifier includes two input differential pairs, the reference voltage and the first feedback voltage being input to one of the two input differential pairs, and the reference voltage and the second feedback voltage being input to other input differential pair.
5 more elements
A power supply apparatus comprising:
- a voltage generation unit generating a driving voltage for driving a load;
- a first feedback path feeding back a voltage according to a voltage at one end of the load;
- a second feedback path feeding back a voltage according to a voltage at the other end of the load;
- and
- a control circuit controlling the voltage generation unit so that one of a first feedback voltage and a second feedback voltage fed back by the first feedback path and the second feedback path, respectively is closer to a predetermined reference voltage;
- wherein the first feedback path includes
- a constant current circuit generating a predetermined constant current;
- and
- a voltage drop circuit provided between the constant current circuit and the voltage generation unit, and generating a voltage drop according to the constant current, and
- the first feedback path feeds back the voltage at the connection point between the constant current circuit and the voltage drop circuit as the first feedback voltage.
7 more elements
A power supply apparatus comprising:
- a voltage generation unit generating a driving voltage for driving a load;
- a current driving circuit provided on a path on which the voltage generation unit drives the load;
- a first feedback path feeding back a first feedback voltage according to the driving voltage;
- a second feedback path feeding back a second feedback voltage according to a voltage at a connection point between the current driving circuit and the load;
- and
- a control circuit controlling the voltage generation unit so that one of the first feedback voltage and the second feedback voltage fed back by the first feedback path and the second feedback path, respectively is closer to a predetermined reference voltage;
- wherein the first feedback path includes
- a constant current circuit generating a predetermined constant current;
- and
- a voltage drop circuit provided between the constant current circuit and the voltage generation unit, and generating a voltage drop according to the constant current, and
- the first feedback path feeds back the voltage at the connection point between the constant current circuit and the voltage drop circuit as the first feedback voltage.
8 more elements
Dependencies are inferred from the claim text.