Rohm Co., Ltd.

Tsutomu Ishino

Shun Fukushima

Tomohisa Shinozaki

Tetsuro Hashimoto

Tadayuki Sakamoto

Disclosed is a control circuit of a boost DC-DC converter including a high side transistor and a low side transistor, and a load switch connected between the high side transistor and an output line of the boost DC-DC converter. The control circuit includes a pulse modulator that generates a pulse signal with a pulse modulated to bring an output voltage of the output line close to a target level, a logic circuit that generates a high side control signal and a low side control signal based on the pulse signal, a load switch drive circuit that drives a first PMOS transistor provided as the load switch, and a current detection circuit that generates a current detection signal indicating a current flowing through the first PMOS transistor. The load switch drive circuit is switchable between a first mode and a second mode.

Control circuit of boost DC-DC converter, power supply circuit, and electronic device

A control circuit of a boost DC/DC converter including a high side transistor and a low side transistor, includes a pulse modulator including a first error amplifier that amplifies an error between a reference voltage and a feedback signal corresponding to an output voltage of the converter, the pulse modulator being configured to generate a pulse signal with a pulse modulated, a logic circuit that generates a high side control signal and a low side control signal, and a load switch drive circuit that drives a load switch that is a PMOS transistor connected between the high side transistor and a load. The load switch drive circuit can make a switch between a first mode for fully turning on the PMOS transistor and a second mode for supplying a drive voltage corresponding to the output signal of the first error amplifier to a gate of the PMOS transistor.

Control circuit of DC/DC converter, power supply circuit, and electronic device

The present disclosure provides a current detecting circuit, a synchronous rectification type DC/DC buck converter and a control circuit thereof. The current detection circuit is used with a push-pull switching circuit to detect a source current flowing in a low-side transistor. The switching circuit, (i) in a first phase, connects a first end of the capacitor to a ground line, and connects a second end of the capacitor to a switch line connecting a high-side transistor and the low-side transistor. The switching circuit, (ii) in a second phase, sets the first end of the capacitor to a high impedance, and connects a second end of the capacitor to the ground line. An output circuit has a high impedance input and outputs a current detection signal based on a voltage generated at the first end of the capacitor in the second phase.

Current detection circuit, synchronous rectification type DC/DC buck converter and control circuit thereof

The present disclosure relates to a buck DC/DC converter, a controller thereof and controlling method thereof, and an electronic device. A pulse modulator generates a pulse modulation signal such that an output of the buck DC/DC converter is pulse-modulated to approach a target state. An overcurrent detection circuit compares a low-side current flowing through a low-side transistor with a predetermined overcurrent threshold value to generate an overcurrent detection signal that is asserted when the low-side current is greater than the overcurrent threshold value. (i) In a first mode, the control pulse that is input to the driver circuit corresponds to the pulse modulation signal, and (ii) in a second mode, the control pulse takes a second level for a period during which the overcurrent detection signal is asserted and takes a first level during a fixed on time after the overcurrent detection signal is negated.

Buck DC/DC converter, controller thereof and controlling method thereof, and electronic device

The present disclosure relates to a high-side transistor drive circuit, a switching circuit and a controller of a DC/DC converter. A pulse generator generates a first pulse that becomes high level for a certain period of time in response to a first edge of an input signal and a second pulse that becomes high level for a certain period of time in response to a second edge of the input signal. An open drain circuit has a first output node that becomes low level in response to the first pulse and a second output node that becomes low level in response to the second pulse. A first current mirror circuit folds back a first current flowing through the first output node of the open drain circuit. A second current mirror circuit folds back a second current flowing through the second output node of the open drain circuit.

Drive circuit of high-side transistor, switching circuit, and controller of DC/DC converter

A slew rate control device for controlling a slew rate, includes: a setting part configured to set a voltage value used to determine the slew rate; and a control part configured to control the slew rate, based on the voltage value set by the setting part, so that the slew rate becomes slower as an output voltage of a power supply approaches from a transition starting voltage to a target voltage.

Device and method for controlling slew rate

The present invention improves the efficiency of a switching power supply in a light load. A control circuit is configured to repeat a driving duration enabling the switching element to be switched and a stop duration stopping the switching in a light load state. A pulse signal generating portion generates a driving pulse signal, in which the driving pulse signal at least includes a pulse in the driving duration, and the lighter a load is, the less the number of pulses in the driving duration is. A first driver drives a first switching transistor according to the at least one pulse in the driving pulse signal other than predetermined K pulses (K is a natural number). The K pulses are in the driving pulse signal when the number of the pulses is reduced to K.

Control circuit and control method for switching power supply, and switching power supply and electronic apparatus using control circuit and control method

A charging circuit receives electric power from a solar battery, and charges a secondary battery. A charging current detection unit generates a detection signal that corresponds to a charging current supplied from a DC/DC converter to the secondary battery. A control circuit generates a reference voltage that corresponds to the detection signal. A driving unit generates a pulse signal having a duty ratio that is adjusted such that the voltage output from the solar battery matches the reference voltage, and performs switching of a switching transistor according to the pulse signal. A control circuit adjusts the reference voltage such that the reference voltage becomes greater.

Charging circuit

An error amplifier generates an error signal Vthat corresponds to the difference between a feedback signal Vand a predetermined reference voltage V. A first oscillator generates a first cyclic signal Vhaving a sloping segment and a first frequency. A second oscillator generates a second cyclic signal Vhaving a sloping segment and a second frequency that is lower than the first frequency. A first pulse modulator generates a first pulse signal having a pulse width that corresponds to the error signal V, and clamps its pulse width such that it does not become smaller than a first minimum pulse width. A second pulse modulator generates a second pulse signal having a pulse width that corresponds to the error signal V. A synthesizing unit combines the first pulse signal and the second pulse signal so as to generate a driving pulse signal.

Control circuit for switching power supply

A pulse signal generating circuit generates a pulse signal having a duty ratio controlled such that the output voltage approaches a reference voltage. A driver circuit generates first and second gate voltages, which are to be respectively applied to the gates of a switching transistor and a synchronous rectifier transistor, based upon the pulse signal. A threshold voltage generating unit generates a threshold voltage which is synchronous with the second gate voltage, and which is in the high-level state during a period when the synchronous rectifier transistor is to be turned off and in the low-level state during a period when the synchronous rectifier transistor is to be turned on. A light-load detection comparator compares a switching voltage with the threshold voltage, and outputs a light-load detection signal.

Step-down type switching regulator

A switching regulator according to the invention includes a resistor (R) and a capacitor (C) for generating a ramp signal from the AC component in the output of a hysteresis comparator (). The switching regulator is characterized in that the hysteresis comparator () compares with a reference voltage outputted from a reference voltage source () a voltage obtained by superimposing the ramp signal on the divided voltage of the output voltage (V) as obtained between resistors (Rand R).

Switching regulator

A power supply unit comprises a series regulator and a switching DC-DC converter controlled by a PWM signal and connected in parallel with the series regulator, which are switchably enabled by a mode instruction signal depending on the magnitude of a load current. In switching the series regulator and the DC-DC converter, they are simultaneously enabled for a predetermined overlapping time. Further, in changing the operating condition of the DC-DC converter, the width of the PWM signal is shortened to extend the dead time of the DC-DC converter by a predetermined period, thereby suppressing free oscillations and accompanying overshoots that could take place in the power supply unit during switching.

Growing community of inventors

Kyoto, Japan

Tsutomu Ishino