| 摘要 |
<p>Each driver circuit 300 for a six-by-four array 200 of light emitting diodes illuminating a pushbutton switch 100 switches three pairs of the light emitting diodes D1-D2, D3-D4 and D5-D6 between series connection and parallel connection based on changes to an applied input voltage. Driving six light emitting diodes instead of only four allows illumination of a larger area and improves power efficiency at higher applied input voltages, while retaining dimming compatibility at low voltage levels. Each driver circuit also includes a rectifier D12-D15 allow illumination of the pushbutton switch with direct current voltages of either polarity. The quiescent current limiting resistance is split into multiple resistors R3-R5 for further improved power efficiency.</p> |
