A switch includes a first switching member and a latch circuit. A first terminal of the first switching member is electrically connected to a power source, while a second terminal thereof is electrically connected to a loading. The latch circuit includes a first transistor and a second transistor which are mutually electrically connected. The first transistor is electrically connected to the first terminal, and the second transistor is electrically connected to the control terminal. By inputting a trigger voltage to the second transistor, the second transistor and the first switching member are conducted, which makes the first transistor become conductive. After the first transistor becoming conductive, the first transistor provides electricity to the second transistor to cause latching effect, and to consequently keep the first switching member conductive.