Other

Mikio Kamiya

Hiroyuki Kimura

Tsutomu Tanaka

Katsunobu Hongo

Kunio Tani

Tomohisa Iba

Toshihiro Sezaki

Tetsu Tashiro

Yasuhiro Ami

A microcomputer comprises: a flash memory for storing rewriting control F/W and user S/F; a command register for specifying content of rewriting control; a address register to be subjected to rewriting-control; a data register for specifying data to be written; a power-supply pump circuit in the flash memory; and a control signal register for specifying/outputting a control signal to a memory decoder. A CPU of the microcomputer is capable of accessing these four registers to perform writing or reading. A given bit of the control signal register corresponds to a given control signal. A value written to the register becomes a control signal that will be directly supplied to both of the power supply circuit and the memory decoder, in the flash memory, to control them. By rewriting a set value of this control signal register using the rewriting control F/W according to a specified sequence, processing such as &ldquo;erase&rdquo; and &ldquo;program&rdquo; of the flash memory is performed. As a result, a layout area of an automatic sequence circuit is decreased, and a change in a sequence is also facilitated.

Microcomputer with built-in programmable nonvolatile memory

A nonvolatile semiconductor memory includes a memory block composed of a memory array having a plurality of memory cells arranged in a matrix form, each of the memory cells being composed of a nonvolatile transistor; a memory decoder necessary for erasing/writing/reading data of the nonvolatile transistor in the memory array; a charge pump necessary for erasing/writing/reading the data of the nonvolatile transistor in the memory array; a register having each of a plurality of control signals for controlling the memory decoder and the charge pump allocated to register 1 bit; and an updating device for updating a content of the register by a data processor coupled to the register. By using this updating device to update the content of the register, the memory decoder and the charge pump are controlled, the data of the memory block is erased, and data is written in/read from the nonvolatile transistor. Thus a selecting device other than a laser can be applied for suppressing the increase of an LSI circuit size in the same chip as that for a dedicated control circuit, verifying the disconnected state of a FUSE circuit in the memory, and trimming the FUSE circuit.

Nonvolatile semiconductor memory and automatic erasing/writing method thereof

Growing community of inventors

Tokyo, Japan

Mikio Kamiya