Sanyo Electric Co., Ltd.

Sanyo Semiconductor Co., Ltd.

Semiconductor Components Industries, LLC

On Semiconductor Trading, Ltd.

Toshiki Rai

Sadao Yoshikawa

With a serial interface memory device of this invention, a read-out rate of data is increased, while an increase in a size of a circuit is suppressed. An EEPROM is provided with a memory cell array storing data, a row address decoder and a column address decoder that select an address of the memory cell array in accordance with an address signal serially inputted in synchronization with a clock, sense amplifiers SA-SA, SA_Mand SA_Meach provided corresponding to each bit of the data, and a shift register that outputs the data read out from the sense amplifiers serially from a first bit. The column address decoder commences reading out two candidate data for the first bit by inputting each of the two candidate data to each of the two sense amplifiers SA_Mand SA_M, respectively, before all bits of the column address signal are established.

Memory device

A reset transistor is prevented from being deteriorated when power-down occurs during a programming operation or an erasing operation. It is made possible to protect the reset transistor as well as other transistors in a circuit to which a high voltage is applied when the power-down occurs during the erasing operation on an EEPROM, because the system is not reset all at once based only on a first reset signal POR of a power-on reset circuit, but is reset based on the first reset signal POR and a low voltage detection signal LD from a low voltage detection circuit so that the reset transistor is not turned on while the high voltage is applied to it.

Reset circuit of high voltage circuit

A memory device including a serial-parallel conversion section that converts serial data into parallel data, a parallel-serial conversion section that converts parallel data into serial data, and a parallel-parallel conversion section that changes a bit width of the parallel data. This memory device connects one external terminal to the serial-parallel conversion section and another external terminal to the parallel-serial conversion section when access using a serial interface is performed. On the other hand, the memory device connects a plurality of external terminals to the parallel-parallel conversion section when access using a parallel interface is performed, thereby enabling the memory device to occasionally realize parallel transfer of data while using a conventional package.

Memory device with parallel interface

There is offered a semiconductor memory device that has reduced number of high withstand voltage transistors so as to suppress an increase in a die size. A second transistor of N channel type is connected between a word line and a decoder circuit. A control signal from a control circuit is applied to a gate of the second transistor. When an output of the decoder circuit is at a low level, the word line is in a non-selected state, and a high voltage from a switching circuit is not outputted to the word line. Instead, the word line is provided with the ground voltage (=non-erasing voltage) from the decoder circuit through the second transistor.

Semiconductor memory device

The invention is mainly directed to providing a charge pump circuit which realizes low power consumption. A first clock signal is supplied from an oscillator circuit to capacitor elements forming a charge pump circuit. A current generation circuit controls a current flowing through each of inverters by controlling operation of PMOS and NMOS, and as a result controls the frequency of the first clock signal. A gate and a drain of PMOS are short-circuited, and between the node thereof and a ground terminal a constant current generation circuit and a resistor are connected in parallel. The constant current generation circuit serves to keep the current flowing through the inverters constant against a change of a power supply voltage. Therefore, the frequency of the clock signal is reduced according to the increase of the power supply voltage.

Charge pump circuit

The invention provides a semiconductor memory device where a circuit area is minimized and a voltage drop in a high voltage supply path to a source line is reduced. An output of a high voltage generation circuit is connected to a source line through a first transfer gate, and connected to a word line through a second transfer gate. The first transfer gate is configured of a P-channel type MOS transistor of which on and off are controlled by a write enable signal, and the second transfer gate is configured of a P-channel type MOS transistor of which on and off are controlled by an erase enable signal. A third transfer gate supplying the output of the high voltage generation circuit to the source line without through a high voltage switching circuit is further provided. The third transfer gate is configured of a P-channel type MOS transistor and an inverted output of the high voltage switching circuit is applied to the gate thereof.

The present invention provides a memory device including a serial-parallel conversion section that converts serial data into parallel data, a parallel-serial conversion section that converts parallel data into serial data, and a parallel-parallel conversion section that changes a bit width of the parallel data. This memory device connects one external terminal to the serial-parallel conversion section and another external terminal to the parallel-serial conversion section when access using a serial interface is performed. On the other hand, the memory device connects a plurality of external terminals to the parallel-parallel conversion section when access using a parallel interface is performed, thereby enabling the memory device to occasionally realize parallel transfer of data while using a conventional package.

A high speed sense amp supplies current to a bit line connected to a memory cell transistor and also detects a potential of the bit line. The potential of the bit line varies according to a conductive state of the memory cell transistor. The sense amp includes a load element and a first transistor connected in series between a first potential and the bit line. A second transistor is connected between the first potential and the bit line. The bit line is input to an inverter that has its output terminal connected to a gate of the first transistor. A differential amp has a first input terminal connected to a reference potential and a second input terminal connected to a node between the load element and the first transistor. The output of the differential amp indicates a difference between the reference potential and the bit line potential.

Sense amplifier with improved sensitivity

A non-volatile semiconductor memory device including a memory cell transistor, a bit line connected to the memory cell transistor, a current controlling element connected between the bit line and a first potential, a dummy cell transistor connected between the bit line and a second potential, and a decoder connected to the memory cell transistor and the dummy cell transistor. The memory cell transistor has an electrically isolated floating gate electrode which varies an on resistance that depends on an amount of charge stored on the floating gate electrode. The decoder, which controls the memory cell transistor and the dummy cell transistor, is operative during a first interval to turn the dummy cell transistor on to apply the second potential to the bit line which is connected to the first potential via said current controlling element and it is operative during a second interval to turn the memory cell transistor on to allow the second potential to be applied to the bit line via the memory cell transistor, thereby allowing a write-in current to pass via the memory cell transistor.

Growing community of inventors

Ogaki, Japan

Toshiki Rai