Seiko Instruments Inc

Hiroki Wake

Fumiyasu Utsunomiya

Michiyasu Deguchi

Kiyoshi Yoshikawa

Toshiyuki Tsuzaki

Osamu Uehara

Hiroyuki Masuko

Provided is a power supply switching circuit capable of efficiently supplying a desired voltage among a plurality of voltages to a load. In the case of a P-type semiconductor substrate, N-type MOS transistors are provided between a load and an AC adapter and between the load and a battery, and hence no parasitic diode exists between the load and the AC adapter or the battery, resulting in no current path due to the parasitic diode. Thus, when the AC adapter and the battery are connected to the power supply switching circuit, the N-type MOS transistor is turned off, whereby the current path between the battery and the load is cut off completely and the N-type MOS transistor is turned on. Accordingly, the battery cannot supply a voltage to the load while only the AC adapter can supply a voltage to the load.

Power supply switching circuit

The present invention has an object to provide a switching regulator power supply apparatus that realizes a plurality of light emitting amount outputs without increasing a total number of structural components thereof. A switching regulator power supply apparatus according to the present invention includes a switching type power converting circuit; a current detecting circuit for producing a feedback signal in response to a load current; and an SWR control circuit for driving the power converting circuit. In the switching regulator power supply apparatus, the SWR control circuit is provided with a control signal input terminal and a reference voltage circuit capable of outputting a plurality of reference voltages based upon a control signal inputted to the control signal input terminal.

Switching regulator

A semiconductor device has a DC-DC converter control circuit for selectively carrying out a boosting operation and a deboosting operation in accordance with a value of a power supply voltage supplied to the DC-DC converter control circuit and for outputting an activation pulse during a rise of the power supply voltage. The DC-DC converter control circuit has a voltage detection circuit for monitoring the power supply voltage to judge whether the DC-DC converter control circuit carries out the boosting operation or the deboosting operation. A control circuit controls the output of the activation pulse in accordance with an output signal from the voltage detection circuit and stops the output of the activation pulse when the voltage detection circuit judges that the DC-DC converter control circuit carries out the deboosting operation.

Buck/boost DC-DC converter control circuit with input voltage detection

A semiconductor memory device has an external terminal receptive of a voltage for switching an operation mode. A protective transistor is connected between the external terminal and a ground. The protective transistor has a drain region and a gate electrode surrounding the drain region. A voltage detection circuit detects a voltage of the external terminal and outputs a switching signal for switching a first operation mode to a second operation mode when a value of the detected voltage is equal to or higher than a preselected voltage value.

Semiconductor memory device

The semiconductor storage device includes: a booster circuit ( ) for boosting a power supply voltage ( ) supplied to the IC; and a limiter circuit ( ) having a function of performing voltage limitation of a high voltage which is a booster circuit output. The limiter circuit selects one voltage value from two values based on whether it is a data recording/erasing time or an evaluation time, to output the one to the memory circuit block

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Chiba, Japan

Hiroki Wake