Load driver with first and second series converters
View Patent ↗A load driver includes: a rectifying unit configured to rectify an AC voltage from a power source to generate a first voltage; a first converter configured to convert the first voltage outputted from the rectifying unit into a second voltage; a second converter configured to drive a load with a constant current, based on the second voltage converted by the first converter; and a feedback unit configured to generate feedback information, based on information obtained from the second converter and indicating an output voltage when the second converter drives the load with the constant current, wherein the first converter converts the first voltage into the second voltage having a magnitude based on the feedback information obtained from the feedback unit.
1. A load driver comprising:
a rectifying unit configured to rectify an AC voltage from a power source to generate a first voltage;
a first converter configured to convert the first voltage outputted from the rectifying unit into a second voltage;
a second converter configured to drive a load with a constant current, based on the second voltage converted by the first converter; and
a feedback unit configured to generate feedback information, based on information obtained from the second converter and indicating an output voltage when the second converter drives the load with the constant current,
wherein the first converter converts the first voltage into the second voltage having a magnitude so that a difference between the second voltage and the output voltage becomes a desired value, based on the feedback information obtained from the feedback unit,
wherein the feedback unit includes:
a reference voltage generating unit configured to use the output voltage and a first reference voltage, which is a constant voltage, to generate a second reference voltage; and
a feedback generating unit configured to generate a feedback voltage as the feedback information, based on the second reference voltage and the second voltage.
2. The load driver according to claim 1 ,
wherein the reference voltage generating unit includes
a reference voltage setting circuit configured to output the second reference voltage if the first reference voltage and the output voltage are inputted, and
wherein the feedback generating unit includes
an error amplification circuit configured to output an error current according to a difference between the second reference voltage and a divided voltage, if the second reference voltage and a divided voltage of the second voltage is inputted.
3. The load driver according to claim 2 ,
wherein the feedback voltage generating unit further includes
a feedback voltage output circuit configured to output the feedback voltage having a magnitude according to the error current.
4. The load driver according to claim 2 ,
wherein the reference voltage setting circuit includes
a differentiation circuit configured to control a magnitude of the second voltage when starting of the load driver.
5. The load driver according to claim 1 , further comprising
a reference voltage source configured to output the first reference voltage if the second voltage is inputted.
6. The load driver according to claim 1 ,
wherein each of the first and second converters is a converter having any one of step-up function and a step-down function.
7. The load driver according to claim 1 ,
wherein the first voltage generated from the rectifying unit is any one of a voltage, which is rectified from the AC voltage, and a voltage, which is rectified and smoothed from the AC voltage.