Semiconductor integrated circuit device capable of switching mode for trimming internal circuitry through JTAG boundary scan method

A semiconductor integrated circuit device comprises a control unit for switching a mode about the trimming or estimation in an internal circuit, the control unit including a controller capable of realizing the mode switching control about the trimming or estimation by the JTAG method. The controller includes an instruction decoder for decoding an input instruction, a shift scan register circuit for enabling a boundary scan based on the decoded result of the instruction decoder, and an operation controller for controlling the operations of the instruction decoder and the shift scan register circuit. Therefore, the trimming becomes possible after sealing a semiconductor chip into a package.