Torex Semiconductor Ltd.

Device Engineering Co., Ltd.

Torex Device Co., Ltd.

Norimasa Hane

Takeshi Naka

Satoru Ohkawa

Kenichi Watanabe

A switching power supply circuit includes: an error amplifier for amplifying a deviation between a reference voltage and a feedback voltage; a comparator for comparing the reference voltage with an output voltage of the error amplifier, and outputting a predetermined set signal; an ON-time control circuit for defining a period during which a switching element is ON; a flip-flop circuit which is set by the set signal to bring the switching element into an ON- or OFF-state, and is reset by an output signal of the ON-time control circuit to bring the switching element into an OFF- or ON-state; a ripple voltage detection circuit for connecting an integration circuit in parallel to an inductance coil, thereby detecting a ripple voltage contained in the output voltage; and a capacitor connected between the output side of the error amplifier and a junction of a resistor and a capacitor of the integration circuit.

Switching power supply circuit having a switching element and a free-wheeling element and adapted to turn on or off at least the switching element

Each of a plurality of reference voltage sources having different temperature characteristics has a reference voltage generation unit which generates a predetermined reference voltage having intrinsic temperature characteristics showing a peak voltage at different temperatures, an amplification circuit which compares the reference voltage and a feedback voltage to control an output transistor, the output transistor which generates a reference output voltage at an output terminal, and a voltage regulation unit which is able to regulate an output voltage so as to become the reference output voltage and generates the feedback voltage. A maximum reference output voltage which is the maximum of the reference output voltages is output through the output terminal.

Reference voltage generation circuit

A switching power supply circuit comprises: a differential amplification stage for outputting an error signal representing a difference voltage between a preset reference voltage and a voltage based on an output voltage; an ON-time generation circuit for defining a period of time during which a main switching element is kept ON; a flip-flop circuit which is set by a set signal based on the error signal and reset by a reset signal being an output of the ON-time generation circuit; current information means for detecting current information representing a current flowing to a subordinate switching element; current information detecting means for supplying a current information detecting signal, which makes an adjustment based on the current information so as to delay the timing of the rise of the set signal, to the output side or the interior of the differential amplification stage; and current information holding means for holding the current information detected by the current information means at a moment when the subordinate switching element is turned on, and supplying a current information holding signal, which makes an adjustment so as to advance the timing of the rise of the set signal, to the output side or the interior of the differential amplification stage.

Switching power supply circuit in a synchronous rectification mode for alternately turning on and off a main switching element and a subordinate switching element

A switching power supply circuit includes: a comparator for comparing a reference voltage, which is an output signal of a reference voltage generation circuit, with a feedback voltage, and outputting a set signal when a difference between the reference voltage and the feedback voltage exceeds a predetermined threshold value; an ON-time generation circuit for generating an ON-time signal for defining a period of time during which a switching element is kept ON; and a flip-flop circuit which turns on or off the switching element by the set signal and turns off or on the switching element by the ON-time signal. The reference voltage generation circuit has a first reference power supply for generating a first reference voltage, a second reference power supply for generating a second reference voltage, a capacitor, a resistor, and switch means.

Switching power supply circuit

A step-up switching power supply circuit is provided. Within a delay period immediately after start of operation, a switching element (SW) is subjected to constant-current control by a switching control signal (E) of a constant-current source buffer circuit (). Control is also effected such that during halt of control for a stepping-up action in this circuit, or within the delay period, when an output voltage (VOUT)&#x3c;an input voltage (VIN), a switching element (SW) is brought into the ON state, and simultaneously, a switching element (SW) is brought into the OFF state, or when VOUT&#x3e;VIN, the switching element (SW) is brought into the OFF state, and simultaneously, the switching element (SW) is brought into the ON state, and after a lapse of the delay period, the switching element (SW) is in the OFF state, and the switching element (SW) is in the ON state, no matter which of the output voltage (VOUT) and the input voltage (VIN) is higher when compared by a comparator ().

Step-up switching power supply circuit

A DC/DC converter includes a main switching element and a subordinate switching element, and is arranged to supply power to load via a coil. The ON-time of a subordinate switching element in a succeeding cycle is controlled based on a period of time tdif from the time when the subordinate switching element is turned off until the time when voltage at the point of connection of the two switching elements reaches a predetermined threshold value.

DC/DC converter

A switching power supply circuit has a current mode control circuit including current detection means, and current mode signal generation means for generating a current mode signal being a drain current of a first MOS transistor obtained by supplying a first current information signal, which is an output signal of the current detection means, to the gate of the first MOS transistor, and by connecting a first resistance to the source of the first MOS transistor, and supplies the current mode signal to a feedback control system of the switching power supply circuit.

A PWM/PFM control circuit has a differential time generating means for forming a differential time signal representing a differential time corresponding to a difference between the pulse width of a PWM control signal and the pulse width of a PFM control signal on condition that the pulse width of the PWM control signal is smaller than the pulse width of the PFM control signal, and the oscillation frequency of a reference signal serving as a reference for forming the PWM control signal is controlled based on the differential time signal to a low value in accordance with the differential time.

PWM/PFM control circuit and switching power supply circuit

A switching power supply circuit comprises: current detection means for detecting a current flowing through an inductor; current holding means for holding the current flowing through the inductor over a past predetermined period; and current superposition means for adding to an output of an error amplifier a current superposition signal which makes an adjustment, based on a present current information signal as an output signal of the current detection means, such that the ON-period of a switching signal of a PWM comparator is shortened, and also makes an adjustment, based on a past current information signal as an output signal of the current holding means, such that the ON-period of the switching signal of the PWM comparator is lengthened.

A control circuit for a DC/DC converter which includes a main switching element, a sub switching element, and a reactor in order to convert a DC input voltage to a DC output voltage. The control circuit comprises a clock signal generator for generating a clock signal during a blank period in which both the main and sub switching elements are off; a comparator for comparing a reference voltage and a voltage at a connection point between the main and sub switching elements and for outputting a comparison signal indicating a relation of magnitude between the reference voltage and the voltage at the connection point; and an operation mode switching section for monitoring the comparison signal at a timing corresponding to the clock signal in order to detect a voltage state at the connection point, and controlling the sub switching element in accordance with the voltage state.

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Tokyo, Japan

Norimasa Hane