A current drive circuit is provided with a bias generator and a current output unit; wherein the bias generator is provided with: p-channel MOS transistor, p-channel MOS transistor, and reference current source; and the current output unit is provided with: p-channel MOS transistor, switch means, p-channel MOS transistor, and output terminal. The communications system includes a computer and a call-routing database in a memory operably associated with the computer. The block power logic may be to: receive a first request to initiate a first reduced power mode in the at least one functional block, and in response to the first request, send a notification signal to a central power controller. When the solder layer is melted, the guide portion guides a portion of the melted solder to the other side face.