Rohm Co., Ltd.

Masaki Omi

Naoki Takahashi

Muga Imamura

Yohei Okuno

Toru Takahashi

Fumihiko Terasaki

An antenna driving device includes an antenna driving circuit arranged to generate driving current of a transmission antenna, a power supply circuit arranged to generate an output voltage from an input voltage so as to supply the output voltage to the antenna driving circuit, and a logic circuit arranged to control the antenna driving circuit and the power supply circuit. The power supply circuit has a function of temporarily disabling current feedback control so as to perform voltage feedback control using a reference value just before halting the drive of the transmission antenna when the power supply circuit restarts to drive the transmission antenna, or has a function of performing variable control of a reference value for current feedback control in accordance with a rising edge of the driving current when the power supply circuit restarts to drive the transmission antenna.

Antenna driving device

A load driving device includes a switch element configured to generate an output voltage to a load from an input voltage depending on an ON/OFF operation thereof, a switch controller configured to control the ON/OFF operation of the switch element such that a feedback voltage obtained by subtracting a dropped voltage of the load from the output voltage and a predetermined reference voltage are maintained to be consistent, and a variable current source configured to perform ON/OFF controlling of a driving current flowing to the load in response to a driving current control signal. When the switch element is in an ON state at an OFF timing of the driving current, the switch controller maintains the switch element in the ON state thereafter, and turns off the switch element when the ON period of the switch element reaches a predetermined period.

Load driving device and electronic device using the same

A drive unit has a load driving portion driving a load by a PWM drive method; a soft-start function portion for achieving a soft-start function; and a soft-start disabling portion counting a time elapsed after a PWM signal is turned on at start-up of the unit, and disabling the soft-start function when a count value reaches a predetermined value.

Drive unit, smoothing circuit, DC/DC converter

A power supply device has an error amplifier producing an error voltage by amplifying a difference between a feedback voltage according to an output voltage and a predetermined reference voltage, an output portion producing a desired output voltage from an input voltage in such a way that the error voltage is reduced, and a clamping portion setting, during a predetermined period after startup of the power supply device, an upper limit of the error voltage to a value that is lower than a value obtained at normal times, such that the lower the input voltage the higher the upper limit, the higher the input voltage the lower the upper limit.

Power supply device including a clamping portion to limit and error voltage and electronic appliance provided therewith

A step-up switching power supply device with synchronous rectification includes a first switch that is turned on at startup of the device and a second switch that is turned on when an output voltage reaches an input voltage, the first and seconds switches being connected in parallel between the back gate and the source of a synchronous rectifier transistor.

Step-up switching power supply device, and electronic device provided therewith

A power supply device includes a clamp circuit that increases the upper limit value of an error voltage stepwise after the device is started up. This makes it possible to shorten the rise time of an output voltage and to reduce the maximum current at start-up.

Power supply device and electronic appliance therewith

A switching regulator comprises a reverse current detecting transistor (P) having a gate and a source between which a voltage across a synchronous-rectification transistor (P) is applied. When the reverse current detecting transistor (P) comes into an open or closed state (on-state) indicating detection of a reverse current during an on-period of the synchronous-rectification transistor (P), the synchronous-rectification transistor (P) is turned off even before the end of the on period.

Switching regulator with reverse current detecting transistor

A switching power supply IC () is provided with, in a form integrated into an integrated circuit: a terminal (T) whereupon an input voltage (Vin) is applied through an inductor (Lex); a terminal (T) from which an output voltage (Vout) for a loading LED is extracted; a transistor (N) connected between the terminal (T) and a grounding end; a transistor (P) connected between the terminal (T) and the terminal (T); a transistor (P) connected between the terminal (T) and a backgate of the transistor (P); and a switching control section (CTRL) for performing switching control to each transistor. During a step-up operation, the switching control section (CTRL) controls the switching of the transistors (N, P) complementarily to each other while continuously keeping the transistor (P) on, and turns off all of the transistors (N, P, P) when a step-up operation is stopped.

Output device and electronic device provided with same

A switching regulator () includes a sense resistor (Rs), a sense current generating circuit () for generating a sense current (Isense) commensurate with a sense voltage (Vsense), a slope current generating circuit () for generating a slope current (Islope) with a ramped or triangular waveform, a slope voltage generating circuit () for generating a slope voltage (Vslope) commensurate with a summed current (Isense plus Islope), an error amplifier (ERR) for generating an error voltage (Verr) commensurate with an error of an output, a comparator (CMP) for comparing the error voltage (Verr) with the slope voltage (Vslope) to generate a PWM signal and a switching control section (CTRL) for turning on and off an output transistor (N) based on the PWM signal.

Growing community of inventors

Kyoto, Japan

Masaki Omi