Switching regulator
The present invention has an object to provide a switching regulator power supply apparatus that realizes a plurality of light emitting amount outputs without increasing a total number of structural components thereof. A switching regulator power supply apparatus according to the present invention includes a switching type power converting circuit; a current detecting circuit for producing a feedback signal in response to a load current; and an SWR control circuit for driving the power converting circuit. In the switching regulator power supply apparatus, the SWR control circuit is provided with a control signal input terminal and a reference voltage circuit capable of outputting a plurality of reference voltages based upon a control signal inputted to the control signal input terminal.
1. A switching regulator control circuit, comprising:
a feedback signal terminal for inputting thereinto a feedback signal produced in response to a current flowing through a load, where the load comprises a LED;
a reference voltage circuit configured to output one of a plurality of discrete reference voltages based on a control signal, where each discrete reference voltage corresponds to one of a plurality of different luminance stages of the LED;
an error amplifying circuit for inputting thereinto the feedback signal and the one of the plurality of discrete reference voltages to amplify a difference therebetween;
a triangular wave oscillating circuit for oscillating a triangular wave; and
a comparator for comparing an output signal of the error amplifying circuit with the triangular wave to output a switching signal,
wherein the reference voltage circuit is further configured to switch between the plurality of discrete reference voltages based upon the control signal to output a switched reference voltage.
2. The switching regulator control circuit according to claim 1 , further comprising a terminal for inputting the control signal from an external source.
3. A switching regulator power supply apparatus, comprising:
a power supply input terminal for inputting thereinto electric power of a power supply;
a switching type power converting circuit for converting the electric power into electric power capable of driving a load;
the load which is driven by the electric power of the power converting circuit;
a current detecting circuit for producing a feedback signal in response to a current flowing through the load; and
the switching regulator control circuit for driving the power converting circuit in response to a feedback signal the switching regulator control circuit comprising: a feedback signal terminal for inputting thereinto a feedback signal produced in response to a current flowing through a load, where the load comprises a LED; a reference voltage circuit configured to output one of a plurality of discrete reference voltages based on a control signal, where each discrete reference voltage corresponds to one of a plurality of different luminance stages of the LED; an error amplifying circuit for inputting thereinto the feedback signal and the one of the plurality of discrete reference voltages to amplify a difference therebetween; a triangular wave oscillating circuit for oscillating a triangular wave; and a comparator for comparing an output signal of the error amplifying circuit with the triangular wave to output a switching signal, wherein the reference voltage circuit is further configured to switching between the plurality of discrete reference voltages based upon the control signal to output a switched reference voltage.
4. The switching regulator power supply apparatus according to claim 3 , wherein:
the load includes an LED; and
and a current supplied to the LED is switched to change luminance.
5. The switching regulator power supply apparatus according to claim 4 , wherein the LED emits light by switching between at least a normal LED turn-on condition and an LED flash emitting condition.