| 摘要 |
An LED AC drive circuit, comprising: a rectification unit, a current-limiting unit, M LED units, and M-1 connected/disconnected control connection lines; each LED unit comprising ni LEDs connected in series, wherein 1≤i≤M, and n1+n2+…+nM＝N, 1≤M≤N, and N is determined by formula (I). The M LED units are connected sequentially to the positive end of the rectification unit and to the current-limiting unit connected to the negative end of the rectification unit; the first LED unit comprises switches connected in series at the negative end of the LED string; the ith LED unit comprises switches connected in series at the positive end of the LED string and switches connected in series at the negative end of the LED string, wherein 1≤i≤M-1; and the Mth LED unit comprises switches connected in series at the positive end of the LED string. The serial or parallel connection state of each LED unit is changed by changing the on/off state of each switch and the connected/disconnected state of the control connection lines, allowing all LEDs to work normally within each voltage range of the pulsating direct current. |
