WRITE PROHIBITION CIRCUIT, SEMICONDUCTOR INTEGRATED CIRCUIT CONTAINING THE SAME, INK CARTRIDGE HAVING THIS SEMICONDUCTOR INTEGRATED CIRCUIT, AND INK JET RECORDER

摘要

In a write-inhibit circuit that uses a data-writing request signal WR as an input and that uses a write-control signal WRITE to inhibit data writing, a chip area is reduced and the operating current is reduced. In a current-mirror circuit CM, by comparing a reference current Iref and a current ID flowing across the source and drain of an N-transistor T3, the voltage of a high potential power supply VDD can be detected. In other words, the voltage value of the high potential power supply VDD is sufficiently high, the data-writing request signal WR is unchanged and output as a write-control signal. Conversely, when the voltage value of the high potential power supply VDD decreases due to some reason, a transistor T6 used for a reference-current supply and a buffer gate B2 operate so that the write-control signal is at "L" irrespective of whether the data-writing request signal WR is either at "H" or at "L". In other words, when the power-supply voltage decreases, miswriting can be prevented since writing by the data-writing request signal WR is impossible. IMAGE