Current control circuit and method for floating IC driven buck-boost converter

摘要

A buck-boost LED driver circuit is provided with floating IC driving control. A DC power supply is provided with first and second inputs, the second input coupled to a mains ground. A PFC switching circuit is coupled to the first input and operable to drive an LED load. A current sensor is coupled to the switching circuit and configured to provide feedback signals representative of current through the LED load, and a dimming control circuit is coupled to the mains circuit ground and effectively superposes an external dimming control signal with the load feedback signal. A PFC controller is configured to provide driver signals to a switching element based on the superposed dimming and load feedback signals as compared to an internal reference. Each of the switching element, the current sensor and the controller are commonly coupled to a floating circuit ground.

主权项

1. An LED driver circuit comprising:
first and second DC input terminals, the second DC input terminal coupled to a first circuit ground; a PFC switching circuit block comprising a PFC controller and a switching element coupled on a first end to the first DC input terminal and on a second end to a second circuit ground; an output circuit block comprising
a buck-boost inductor coupled on a first end to the first circuit ground and on a second end to the second circuit ground, anda first current sensor coupled on a first end to the second circuit ground; and a dimming control circuit block comprising a second current sensor coupled between a second end of the first current sensor and a feedback input terminal on the PFC controller, the dimming control circuit block further coupled to the second circuit ground.