| 摘要 |
<p>Provided is an LED drive circuit, wherein switching is conducted between LED blocks, according to the power supply voltage and the forward voltage drops (Vf) inherent to the LEDs contained in each of the LED blocks. The LED drive circuit comprises a rectifier; a first circuit that has a first LED group, a first current detection unit that detects a current flowing from the first LED group to the minus output terminal of the rectifier, and a first current limiting unit that limits the current flowing from the first LED group to the minus output terminal of the rectifier according to the current detected by the first current detection unit; and a second circuit that has a second LED group, and a current path through which a current flows through the second LED group to the minus output terminal of the rectifier. A current path whereby only the first LED group is connected to the rectifier, or a current path whereby the first LED group and the second LED group are connected in series to the rectifier is formed, according to the output voltage of the rectifier, and the LED drive circuit makes the first current limiting unit function when the first current detection unit detects a current flowing through the first LED group and the second LED group, and switches the current path.</p> |
