A data transmitting method used in a semiconductor device having a controller and a transmitter is described. A first write command is output by the controller and then a second write command is output by the controller. An interval time between the first write command and the second write command is calculated. The transmitter is activated by the controller and a first data is transmitted by the transmitter in accordance with the first write command, and then the transmitter is inactivated based on the interval time. Then the transmitter is activated when the transmitter is inactivated. Then, the second data is transmitted by the transmitter in accordance with the second write command.