Patent attributes
In a PC card communication terminal that operates supplied with power from a host device, problems such as malfunctions due to a supply voltage drop at the time of high transmission output are prevented from occurring. A baseband processor (1106) selects a transmission-power upper-limit measurement mode when a PC card terminal (1103) is to be controlled for the first time. A supply voltage drop is measured by a voltage measurement circuit (1114) while a load value of a load circuit (1112) is being changed. The load value of the load circuit (1112) when the supply voltage decreases to a permissible lowest supply voltage is obtained. Using a conversion table stored in a memory (1107), the load value is converted into a transmission output and is set as a transmission-output upper limit. In a normal communication mode, a maximum transmission output is restricted based on this transmission-output upper limit.
