Abstract: A memory device includes m memory cell blocks, m×(k+1) word lines, n bit lines, and a word line driver circuit (m, k, and n are each an integer greater than or equal to 1). The memory cell block includes memory cells of (k+1) rows×n columns, and each of the memory cells is electrically connected to a word line and a bit line. The word line driver circuit has a function of outputting signals to m×k word lines that are selected from m×(k+1) word lines by using a switch transistor, and selection information is written to a gate of the switch transistor by using a transistor having a low off-state current. The memory cells of k rows×n columns included in the memory cell block are normal memory cells, and each of the memory cell blocks includes redundant memory cells of one row×n columns.

Abstract: A semiconductor device storing data as a multilevel potential is provided. The semiconductor device includes a memory cell, first and second reference cells, first and second sense amplifiers, and first to third circuits. The first circuit has a function of outputting, to a first wiring and a third wiring, a first potential corresponding to a first signal output from the memory cell. The second circuit has a function of outputting, to a second wiring, a first reference potential corresponding to a second signal output from the first reference cell. The third circuit has a function of outputting, to the fourth wiring, a second reference potential corresponding to a third signal output from the second reference cell when a second switch is in an off state. The first sense amplifier refers to the first potential and the first reference potential and changes potentials of the first wiring and the second wiring.

Abstract: A semiconductor device with less variation in transistor characteristics is provided. The semiconductor device includes a transistor, a first and a second conductor, and a first to a third insulator. The transistor and the first conductor are provided over the first insulator. The transistor includes an oxide semiconductor. The second insulator is provided over the transistor. The first conductor includes a region which does not overlap with the second insulator. The third insulator is provided to cover the first conductor, the transistor, and the second insulator. The second conductor is provided over the third insulator and at least partly overlaps with the first conductor.

Abstract: A first transistor, a second transistor, a capacitor, and first to third conductors are included. The first transistor includes a first gate, a source, and a drain. The second transistor includes a second gate, a third gate over the second gate, first and second low-resistance regions, and an oxide sandwiched between the second gate and the third gate. The capacitor includes a first electrode, a second electrode, and an insulator sandwiched therebetween. The first low-resistance region overlaps with the first gate. The first conductor is electrically connected to the first gate and is connected to a bottom surface of the first low-resistance region. The capacitor overlaps with the first low-resistance region. The second conductor is electrically connected to the drain. The third conductor overlaps with the second conductor and is connected to the second conductor and a side surface of the second low-resistance region.

Abstract: A secondary battery deteriorates due to repeated charging and discharging, which leads to a decrease in a battery voltage and a battery capacity. The lifetime of a secondary battery is prolonged by preventing charging at an excessive charging value that would be caused by deterioration of the secondary battery. By performing charge control in consideration of the degree of deterioration of a secondary battery, a longer lifetime of a secondary battery can be achieved. In charging a secondary battery, a charge control circuit controls a current value to a preset value, and a charging current control circuit (specifically a circuit including an error amplifier) included in a protection circuit determines a current value supplied to the secondary battery. That is, the current value supplied to the secondary battery is controlled by both the charge control circuit and the charging current control circuit that is a part of the protection circuit.

Abstract: A semiconductor device having a large storage capacity per unit area is provided. The semiconductor device includes a stack, and the stack includes a first insulator, a first conductor over the first insulator, and a second insulator over the first conductor. The stack includes a first opening provided in the first insulator, the first conductor, and the second insulator and an oxide on the inner side of the first opening. Furthermore, in the first opening, a third insulator is positioned on the outer side of the oxide, a second conductor is positioned on the inner side of the oxide, and a fourth insulator is positioned between the oxide and the second conductor. The third insulator includes a gate insulating layer positioned at a side surface of the first opening, a tunnel insulating layer positioned on the outer side of the oxide, and a charge accumulation layer positioned between the gate insulating layer and the tunnel insulating layer.

Abstract: A semiconductor device that detects deterioration of a secondary battery is provided. The semiconductor device includes a power gauge, an anomalous current detection circuit, and a control circuit. The power gauge includes a current divider circuit and an integrator circuit. The anomalous current detection circuit includes a first memory, a second memory, and a first comparator. The integrator circuit can convert a detection current detected at the current divider circuit into a detection voltage by integrating the detection current. The anomalous current detection circuit is supplied with the detection voltage, a first signal at a first time, and a second signal at a second time. The first signal can make the detection voltage at the first time be stored in the first memory and the second signal can make the detection voltage at the second time be stored in the second memory.

Abstract: A battery protection circuit with a novel configuration and a power storage device including the battery protection circuit are provided. The battery protection circuit includes a switch circuit for controlling charge and discharge of a battery cell; the switch circuit includes a mechanical relay, a first transistor, and a second transistor; the switch circuit has a function of controlling electrical connection between a first terminal and a second terminal; the mechanical relay has a function of breaking electrical connection between the first terminal and the second terminal; the first transistor has a function of supplying first current between the first terminal and the second terminal; the second transistor has a function of supplying second current between the first terminal and the second terminal; and the first current is higher than the second current.

Abstract: A semiconductor device capable of detecting a micro-short circuit of a secondary battery is provided. The semiconductor device includes a first source follower, a second source follower, a transistor, a capacitor, and a comparator. A negative electrode potential and a positive electrode potential of the secondary battery are supplied to the semiconductor device, a first potential is input to the first source follower, and a second potential is input to the second source follower. A signal for controlling the conduction state of the transistor is input to a gate of the transistor, and an output potential of the first source follower related to the potential between the positive electrode and the negative electrode of the secondary battery is sampled.

Abstract: A novel semiconductor device that is highly convenient or reliable is provided. The semiconductor device includes a sensor unit, a first memory unit, a second memory unit, and a determination unit. The sensor unit supplies a sensor signal, the first memory unit retains the sensor signal, the second memory unit retains standard data and allowable difference information, the determination unit compares the sensor signal with the standard data, and the determination unit supplies a control signal in the case where a difference between the sensor signal and the standard data exceeds the allowable difference information.

Abstract: A battery control circuit with a novel structure, a battery protection circuit with a novel structure, and a power storage device including either of the battery circuits are provided. The power storage device includes a first circuit portion, a second circuit portion, a third circuit portion, and a secondary battery; the first circuit portion has a function of controlling charging of the secondary battery; the first circuit portion has a function of supplying the start time and the end time of the charging of the secondary battery to the third circuit portion; the second circuit portion has functions of generating a first voltage and a first current and supplying them to the third circuit portion; the third circuit portion has a function of generating a second voltage by charging the first current in a capacitor; and the third circuit portion has a function of comparing the first voltage and the second voltage.

Abstract: The safety is ensured in such a manner that with an abnormality detection system of a secondary battery, abnormality of a secondary battery is detected, for example, a phenomenon that lowers the safety of the secondary battery is detected early, and a user is warned or the use of the secondary battery is stopped. The abnormality detection system of the secondary battery determines whether the temperature of the secondary battery is within a temperature range in which normal operation can be performed on the basis of temperature data obtained with a temperature sensor. In the case where the temperature of the secondary battery is high, a cooling device is driven by a control signal from the abnormality detection system of the secondary battery. The abnormality detection system of the secondary battery includes at least a memory means. The memory means has a function of holding an analog signal and includes a transistor using an oxide semiconductor for a semiconductor layer.

Abstract: A semiconductor device that writes data to, instead of a defective memory cell, another memory cell is provided. The semiconductor device includes a first circuit and a second circuit over the first circuit; the first circuit corresponds to a memory portion and includes a memory cell and a redundant memory cell; a second circuit corresponds to a control portion and includes a third circuit and a fourth circuit. The memory cell is electrically connected to the third circuit, the redundant memory cell is electrically connected to the third circuit, and the third circuit is electrically connected to the fourth circuit.

Abstract: A semiconductor device with a large storage capacity per unit area is provided. The semiconductor device includes a first insulator including a first opening, a first conductor that is over the first insulator and includes a second opening, a second insulator that is over the first insulator and includes a third opening, and an oxide penetrating the first opening, the second opening, and the third opening. The oxide includes a first region at least in the first opening, a second region at least in the second opening, and a third region at least in the third opening. The resistances of the first region and the third region are lower than the resistance of the second region.

Abstract: A memory device in which bit line parasitic capacitance is reduced is provided. The memory device includes a sense amplifier electrically connected to a bit line and a memory cell array stacked over the sense amplifier. The memory cell array includes a plurality of memory cells. The plurality of memory cells are each electrically connected to a bit line. A portion for leading the bit lines is not provided in the memory cell array. Thus, the bit line can be shortened and the bit line parasitic capacitance is reduced.

Abstract: A first transistor, a second transistor, a capacitor, and first to third conductors are included. The first transistor includes a first gate, a source, and a drain. The second transistor includes a second gate, a third gate over the second gate, first and second low-resistance regions, and an oxide sandwiched between the second gate and the third gate. The capacitor includes a first electrode, a second electrode, and an insulator sandwiched therebetween. The first low-resistance region overlaps with the first gate. The first conductor is electrically connected to the first gate and is connected to a bottom surface of the first low-resistance region. The capacitor overlaps with the first low-resistance region. The second conductor is electrically connected to the drain. The third conductor overlaps with the second conductor and is connected to the second conductor and a side surface of the second low-resistance region.

Abstract: A novel memory device is provided. The memory device including a plurality of memory cells arranged in a matrix, and each of the memory cells includes a transistor and a capacitor. The transistor includes a first gate and a second gate, which include a region where they overlap with each other with a semiconductor layer therebetween. The memory device has a function of operating in a “writing mode”, a “reading mode”, a “refresh mode”, and an “NV mode”. In the “refresh mode”, data retained in the memory cell is read, and then the read data is written to the memory cell again for first time. In the “NV mode”, data retained in the memory cell is read, the read data is written to the memory cell again for second time, and then a potential at which the transistor is turned off is supplied to the second gate. The “NV mode” operation enables data to be stored for a long time even when power supply to the memory cell is stopped. The memory cell can store multilevel data.

Abstract: To provide a novel semiconductor device.

Abstract: A semiconductor device that can be miniaturized or highly integrated is provided. The semiconductor device includes a capacitor, an electrode, and an interlayer film. The transistor includes a semiconductor layer, a gate, a source, and a drain; the transistor and the capacitor are placed to be embedded in the interlayer film. Below the semiconductor layer, one of the source and the drain is in contact with the electrode. Above the semiconductor layer, the other of the source and the drain is in contact with one electrode of the capacitor.

Abstract: A semiconductor device enabling high integration is provided. The semiconductor device includes a plug, two capacitors, and two transistors sharing one oxide semiconductor. Each of the transistors includes a stacked-layer structure of a gate insulator and a gate electrode over the oxide semiconductor and an insulator in contact with a side surface of the gate electrode. An opening between the two gate electrodes exposes the insulators in contact with the side surfaces of the gate electrodes, and the plug is in the opening. The capacitor is directly provided over the oxide semiconductor. The side surface area of the capacitor is larger than the projected area of the capacitor.