| 摘要 |
An LED drive circuit, which comprises a transformer, an MOS tube, a power regulating resistor, a direct current isolation circuit, a rectifying circuit, and a voltage control circuit; when the voltage of the control terminal of the voltage control circuit is higher than the threshold voltage of the MOS tube, the MOS tube is on, a current from an external power supply flows through the first winding of the transformer, the MOS tube and the power regulating resistor successively; when the voltage of the power regulating resistor is close to the voltage of the reference terminal of the voltage control circuit, the MOS tube is cut off, the second winding of the transformer charges the capacitor of the MOS tube via the direct current isolation circuit, the rectifying circuit is on, and the first winding of the transformer supplies power to the LED load via the rectifying circuit. |
| 主权项 |
1. An LED drive circuit, comprising a transformer, an MOS tube, a power regulating resistor, a direct current isolation circuit, a rectifying circuit, and a voltage control circuit; wherein:
the transformer comprises a first winding and a second winding; the first winding is connected at one end to an external power supply and at the other end to a source electrode of the MOS tube, a drain electrode of the MOS tube is grounded via the power regulating resistor; the second winding is grounded at one end, and connected at the other end to a grid electrode of the MOS tube via the direct current isolation circuit; the voltage control circuit comprises a control terminal for controlling on/off of the MOS tube, a reference terminal for regulating voltage of the control terminal, and a ground terminal; the control terminal is connected to the external power supply and the grid electrode of the MOS tube, the reference terminal is grounded via the power regulating resistor, and the ground terminal is grounded directly; the transformer and the voltage control circuit cooperate to control on/off of the MOS tube; when the MOS tube is on, a current from the external power supply flows through the first winding of the transformer, the MOS tube and the power regulating resistor successively, and the rectifying circuit is cut off; when the MOS tube is cut off, the second winding of the transformer charges a capacitor of the MOS tube by the direct current isolation circuit, the rectifying circuit is on, and the first winding of the transformer supplies power to an LED load via the rectifying circuit. |
