Seiko Instruments Inc

Ablic Inc.

Sii Semiconductor Corporation

Michiyasu Deguchi

Kosuke Takada

Hiroyuki Masuko

Toshiyuki Tsuzaki

Fumiyasu Utsunomiya

Tsutomu Tomioka

Takao Nakashimo

Akihiro Kawano

Kiyoshi Yoshikawa

Hideyuki Sawai

Osamu Uehara

Tadakatsu Kuroda

Tadashi Kurozo

Hiroki Wake

Kenji Yoshida

Tetsuya Makino

A voltage regulator which includes a differential amplifier circuit containing a first and second input transistors, controlling a gate-source voltage in each of the first and second input transistors including: a current source configured to drive the differential amplifier circuit; the first input transistor containing a gate; the second input transistor containing a gate; and a voltage controller including at least one of a first voltage control circuit to control a voltage at a tail connection point, a second voltage control circuit to control the voltage at the gate of the first input transistor, a third voltage control circuit to control the voltage at the tail connection point, and a fourth voltage control circuit to control the voltage at the gate of the second input transistor.

Voltage regulator and method of controlling voltage regulator

Provided is a voltage regulator capable of stably generating a constant output voltage even in a high temperature environment. The voltage regulator includes: an output transistor; an output terminal connected to a drain of the output transistor and outputting an output voltage; an error amplifier circuit configured to supply a signal obtained by amplifying a difference between a divided voltage of the output voltage and a reference voltage to a gate of the output transistor; and an NMOS transistor connected between the output terminal and a reference potential and configured to turn on, when the voltage regulator reaches a predetermined temperature at which a leakage current flowing in the output transistor is absorbed, to lead the leakage current to the reference potential.

Voltage regulator

Provided is a voltage regulator having a simple circuit configuration in which a protection circuit is not erroneously operated, and delay time of activation of the protection circuit is short. The voltage regulator includes: a protection circuit configured to control an output transistor when an abnormality of the voltage regulator is detected; a first constant current circuit configured to supply operating current to the protection circuit; and a detection circuit configured to detect output current flowing through the output transistor, to thereby control the first constant current circuit. The detection circuit is further configured to detect the output current with a predetermined reference current value. The protection circuit is further configured to control the output transistor so that the output current does not fall below the reference current value.

Short activation time voltage regulator

To provide a DC-DC converter which prevents overshoot from occurring in an output voltage even when a power supply voltage rises from a voltage lower than a desired output voltage of the DC-DC converter to a normal voltage. A DC-DC converter is equipped with a 100% DUTY detection circuit which detects a 100% DUTY state of a PWM comparator, a power supply voltage rise detection circuit which detects a rise in a power supply voltage, and a discharge control circuit which lowers an output voltage of an error amplifier. The DC-DC converter is configured to lower the output voltage of the error amplifier when a power supply voltage rise detection signal is outputted where a 100% DUTY state is reached and the output voltage of the error amplifier is higher than a predetermined voltage.

DC-DC converter

Provided is a switching regulator configured to achieve a 100% Duty state and reduce an occurrence of an overshoot. The switching regulator has a configuration in which a clamp circuit configured to dynamically generate a clamp level clamps an output voltage of an error amplifier in accordance with a peak value of a triangular wave signal.

Switching regulator control circuit and switching regulator

A switching regulator is provided which can prevent overshooting in an output voltage even when a source voltage is returned to a normal voltage from a voltage lower than a desired output voltage of the switching regulator. The switching regulator includes a 100% duty detector circuit that detects that a PWM comparator is in a 100%-duty state and a discharge accelerator circuit that detects that the output of an error amplifier discharges the voltage of a phase compensating capacitor and that accelerates the discharge, and activates the discharge accelerator circuit when the 100% duty detector circuit detects the 100%-duty state.

Switching regulator and electronic apparatus

There is provided a switching regulator including an overcurrent protection circuit which is able to automatically return from an overcurrent state. The switching regulator includes an error amplification circuit which amplifies a difference between a feedback voltage and a reference voltage based on an output voltage and outputs the amplified difference; a PWM comparator which compares an output of the error amplification circuit with an output of a triangular wave oscillation circuit, and controls an output transistor; an overcurrent detection circuit which monitors a load current flowing through a load connected to an output terminal, detects that the load current is an overcurrent, and outputs an overcurrent detection signal causing a switching operation to stop; and a negative feedback control circuit which receives the overcurrent detection signal, and controls the load current to a predetermined current value.

Switching regulator and electronic device

In order to provide a switching regulator having high efficiency even under light load, the switching regulator is configured so that ON/OFF of a switching element is controlled by an output signal of an oscillation circuit having an oscillation frequency controlled by an output signal from an error amplifier. Thereby, the oscillation frequency can be suppressed under light load, thus reducing a switching loss.

Switching regulator

Provided is a switching regulator including an overload protection circuit, which has high accuracy even without requiring adjusting means in a test step. The switching regulator includes: a first triangle wave generation circuit for generating a first triangle wave which controls Duty of a PWM signal; and a second triangle wave generation circuit for generating a second triangle wave for overload detection, which has a crest value smaller than that of the first triangle wave. A ratio between the crest value of the first triangle wave and the crest value of the second triangle wave is set based on respective capacitances or constant currents thereof.

Provided is a switching regulator including a circuit for detecting a short-circuit state easily and reliably, without the need of an adjustment step such as trimming. In accordance with a drive signal of a power switching element of the switching regulator, a discharge circuit is controlled. When the power switching element is short-circuited and becomes the ON state all the time, the discharge circuit stops its operation, and a capacitor is continuously charged. A voltage detection circuit detects that a charge voltage of the capacitor has reached a predetermined potential, to thereby detect the short-circuit state.

Switching regulator with short-circuit detection circuit

Provided is a switching regulator capable of performing stable start-up with a soft-start operation without causing excessive extension of a soft-start time period. In a start-up period, a voltage approximating a feedback voltage (FB) is provided as an initial value of a soft-start reference voltage. The feedback voltage (FB) and the soft-start reference voltage become substantially equal to each other at a moment when the start-up is completed, to thereby realize a smooth transition of an operating state from the start-up to normal control.

A charging and discharging circuit of a triangular wave oscillation circuit includes an inverter circuit; a discharging reference potential generating circuit; a first NMOS transistor having a drain connected with a connection point between a first current source circuit and the capacitor, and a gate connected with the discharging reference potential generated by the discharging reference potential generating circuit; a second NMOS transistor having a gate inputted with the switching signal through the inverter circuit, a drain connected with the gate of the first NMOS transistor, and a source connected with a source of the first NMOS transistor; and a third NMOS transistor having a gate inputted with the switching signal, a drain connected with a connection point between the source of the first NMOS transistor and the source of the second NMOS transistor, and a source grounded.

Triangular wave generating circuit, and charging and discharging control circuit

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

Provided is a switching regulator for preventing generation of an inrush current flowing through a switching element of an output stage, which is provided in the switching regulator. A soft start control circuit () detects a current flowing through a PMOS transistor () serving as a switching element of an output stage. When the detected current is equal to or larger than a current limiting value for limiting the current flowing through the PMOS transistor (), the soft start control circuit () controls the PMOS transistor () to be turned off. Accordingly, it is possible to prevent generation of the inrush current flowing through the PMOS transistor ().

In a maximum duty control state of a switching regulator control circuit, a period of time during which any one of a step-up switching circuit and a synchronous rectification switching circuit is always off is ensured, thereby preventing the switching efficiency from being remarkably deteriorated. In a maximum duty control state, a voltage difference is provided between a limiter voltage that is inputted to a comparator that controls the switching operation of the step-up switching circuit and a limiter voltage that is inputted to a comparator that controls the switching operation of the synchronous rectification switching circuit, to thereby ensure the period of time during which any one of the step-up switching circuit and the synchronous rectification switching circuit is always off.

Growing community of inventors

Chiba, Japan

Michiyasu Deguchi