A low-power semiconductor device is provided. A retention transistor is provided between a control circuit and an output transistor. An output terminal of the control circuit is electrically connected to one of a source and a drain of the retention transistor, and the other of the source and the drain of the retention transistor is electrically connected to a gate of the output transistor. A node to which the other of the source and the drain of the retention transistor and the gate of the output transistor are electrically connected is a retention node. When the retention transistor is in an on state, a potential corresponding to a potential output from the control circuit is written to the retention node. Then, when the retention transistor is in an off state, the potential of the retention node is retained. Thus, a gate potential of the output transistor can be kept at a constant value even when the control circuit is off. Accordingly, even when the control circuit is off, a constant potential can be continuously output from one of a source and a drain of the output transistor, for example.

A low-power semiconductor device is provided. A retention transistor is provided between a control circuit and an output transistor. An output terminal of the control circuit is electrically connected to one of a source and a drain of the retention transistor, and the other of the source and the drain of the retention transistor is electrically connected to a gate of the output transistor. A node to which the other of the source and the drain of the retention transistor and the gate of the output transistor are electrically connected is a retention node. When the retention transistor is in an on state, a potential corresponding to a potential output from the control circuit is written to the retention node. Then, when the retention transistor is in an off state, the potential of the retention node is retained. Thus, a gate potential of the output transistor can be kept at a constant value even when the control circuit is off. Accordingly, even when the control circuit is off, a constant potential can be continuously output from one of a source and a drain of the output transistor, for example.

Described examples include DC to DC converters and systems with switching circuitry formed by four series-connected switches, inductors connected between the ends of the switching circuitry and corresponding output nodes, and with a flying capacitor coupled across interior switches of the switching circuitry and a second capacitor coupled across the ends of the switching circuitry. A control circuit operates the switching circuit to control a voltage signal across the output nodes using a first clock signal and a phase shifted second clock signal to reduce output ripple current and enhance converter efficiency using valley current control. The output inductors are wound on a common core in certain examples.

A device includes a first transistor connected between a first node and an output terminal and a first current source connected between the first node and a supply rail. A circuit includes a second current source connected between the supply rail and a second node, an operational amplifier having a non-inverting input configured to receive a potential set point, and a second transistor connected between the second node and an inverting input of the operational amplifier. An output of the operational amplifier is connected to a control terminal of the second transistor and further connected to a control terminal of the first transistor.

A device includes a first transistor connected between a first node and an output terminal and a first current source connected between the first node and a supply rail. A circuit includes a second current source connected between the supply rail and a second node, an operational amplifier having a non-inverting input configured to receive a potential set point, and a second transistor connected between the second node and an inverting input of the operational amplifier. An output of the operational amplifier is connected to a control terminal of the second transistor and further connected to a control terminal of the first transistor.

In certain aspects, a system includes a voltage controller, wherein the voltage controller includes switches coupled between a voltage supply rail and an output of the voltage controller, each of the switches having a control input, and a control circuit coupled to the control inputs of the switches. The system also includes a timing circuit coupled to the control circuit, wherein the timing circuit includes a delay line, and flops, each of the flops having an input and an output, wherein the input of each of the flops is coupled to a respective node on the delay line, and the outputs of the flops are coupled to the control circuit.

In certain aspects, a system includes a voltage controller, wherein the voltage controller includes switches coupled between a voltage supply rail and an output of the voltage controller, each of the switches having a control input, and a control circuit coupled to the control inputs of the switches. The system also includes a timing circuit coupled to the control circuit, wherein the timing circuit includes a delay line, and flops, each of the flops having an input and an output, wherein the input of each of the flops is coupled to a respective node on the delay line, and the outputs of the flops are coupled to the control circuit.

A regulator includes a driving circuit, an amplifying circuit and an overvoltage protection circuit. The driving circuit is configured to receive an input voltage and provide an output voltage through an output terminal. The amplifying circuit is configured to control the driving circuit according to the output voltage. The overvoltage protection circuit is configured to conduct a first current from the output terminal of the overprotection circuit to a ground terminal. When the overvoltage protection circuit detects that a voltage level of a node coupled to the driving circuit is increased, the overvoltage protection circuit conducts a second current from the output terminal of the overprotection circuit to the ground terminal to lower the output voltage, in which the second current is larger than the first current.

A regulator includes a driving circuit, an amplifying circuit and an overvoltage protection circuit. The driving circuit is configured to receive an input voltage and provide an output voltage through an output terminal. The amplifying circuit is configured to control the driving circuit according to the output voltage. The overvoltage protection circuit is configured to conduct a first current from the output terminal of the overprotection circuit to a ground terminal. When the overvoltage protection circuit detects that a voltage level of a node coupled to the driving circuit is increased, the overvoltage protection circuit conducts a second current from the output terminal of the overprotection circuit to the ground terminal to lower the output voltage, in which the second current is larger than the first current.

A constant current driving circuit and a corresponding photoelectric smoke alarm circuit are provided. The constant current driving circuit includes a reference voltage source module (1), a linear voltage regulator module (3), a level conversion module (2), a current mirror module (4) and a first NMOS transistor. The linear voltage regulator module (3) may control turning on and turning off thereof according to actual requirements, thus electrical energy loss may effectively be reduced for some periodically used devices. The constant current driving circuit and the corresponding photoelectric smoke alarm circuit may provide a constant current source, so that auxiliary output performance remains stable within a full temperature range, a certain timing sequence requirement is met, no standby power is consumed when not working, performance is stable, power consumption is low, and application range is wide.