A breathing assistance apparatus and method of controlling a breathing assistance apparatus is disclosed. In the power down mode, a refresh control unit holds the start address and the end address and controls refresh to be carried out for data only in a region requiring refresh. The control is thus adapted to each operating point and its prevailing flow gain and linearizes the dependence between flow control and flow. The connection pad portion of at least one of the upper wirings is arranged above an upper surface of the insulating member.