Rohm Co., Ltd.

Tadashi Akaho

Kazuhiro Murakami

Yosuke Fukumoto

Masashi Nagasato

Nobukazu Tsukiji

Yasuto Yoshioka

A power supply control apparatus, includes: a driver configured to respectively drive an output transistor and a synchronous rectification transistor configured to generate an output voltage from an input voltage and supply the output voltage to a load; and a controller configured to, in a light load mode in which output feedback control is performed such that a switching frequency of the output transistor becomes lower as the load becomes lighter, during an off period from a time at which both the output transistor and the synchronous rectification transistor are turned off to an on timing of the output transistor based on the output feedback control, periodically turn on the synchronous rectification transistor within a range in which the switching frequency does not fall below a predetermined lower limit value.

Power supply control apparatus and switching power supply including the same

The power supply control device includes a logic circuit for generating a pseudo switch voltage simulating a behavior of a switch voltage generated in the switch output stage, a filter unit that receives input of the pseudo switch voltage and the output voltage or a feedback voltage corresponding to the output voltage and generates a current sense signal simulating a behavior of the inductor current, and a feedback control unit that performs output feedback control of the switch output stage by using the current sense signal.

Power supply control device

The present disclosure relates to a power control device, a driving module and a switching power supply device. The power control device includes: a control terminal, configured to input and output a control signal to and from the driving module; an enable output terminal, configured to output an enable signal to the driving module; a control circuit; and an input/output circuit, configured to have the control signal be a first logic level when the output transistor is turned on and the synchronous rectifier transistor is turned off, and to have the control signal be a second logic level when the output transistor is turned off and the synchronous rectifier transistor is turned on, and to be able to become an input standby state according to an instruction from the control circuit.

Power control device, driving module and switching power supply device

A drive module for use in a switching power supply generating output voltage from input voltage by turning on/off an output transistor and a synchronous rectification transistor includes: a zero-cross detection circuit detecting zero-cross of inductor current flowing when the synchronous rectification transistor is turned on; a drive logic circuit turning on the output transistor and turning off the synchronous rectification transistor when control signal is at first logic level, turning off the output transistor and turning on the synchronous rectification transistor when the control signal is at second logic level, and turning off both the output transistor and the synchronous rectification transistor when the zero-cross is detected; and a logic level switching circuit switching the control signal to third logic level when the zero-cross is detected, wherein the zero-cross detection circuit, the drive logic circuit, and the logic level switching circuit are integrated in a single package.

Drive module, power supply controller and switching power supply

A control circuit for a DC/DC converter including P-channel and N-channel transistors. The control circuit includes: a pulse generator that generates first and second pulse signals for designating turning on/off of the P-channel and N-channel transistors such that a state of the DC/DC converter or a load approaches a target value; first and second drivers that drive the P-channel and N-channel transistors based on the first and second pulse signals; first to fourth lines individually connected to an upper side power supply terminal of the first driver, a lower side power supply terminal of the second driver, a lower side power supply terminal of the first driver, and an upper side power supply terminal of the second driver; and first and second regulators that stabilize voltages of the third and fourth lines to first and second given voltage values. A coupling capacitor is connected between the third and fourth lines.

Synchronous rectification type DC/DC converter

The switching regulator has: a control unit for turning on/off an upper switch and a lower switch in a complementary manner in accordance with an output voltage; and a current extraction unit for extracting a constant current from a first end or a second end of an inductor. When under a light load, the control unit stops the switching control and fixes the upper switch and the lower switch in an off state. The constant current has positive temperature characteristics, wherein the value of the constant current is greater than or equal to a value obtained by subtracting leakage current of the lower switch from leakage current of the upper switch.

Switching regulator, semiconductor integrated circuit, and electronic appliance

A differential circuit includes a first constant current circuit, a second constant current circuit having the same constant current value as the first constant current circuit, a current mirror including a first transistor having a current sink terminal connected to the first constant current circuit, a current drain terminal to which a first input voltage is applied, and a gate short-circuited to the current sink terminal, and a second transistor having a gate connected to the current sink terminal of the first transistor and a current drain terminal to which a second input voltage is applied, and a current output terminal connected to a connection node between a part in which a current based on an output current of the current mirror flows and the second constant current circuit.

Differential circuit including a current mirror

When a voltage difference between a raised output voltage vcp and an input voltage vin is larger than a set voltage value, based on a added-on voltage vup detected by a voltage monitoror a current iu passing through the voltage monitor, the clock generator controlleris activated. Then the clock generator controllerdraws in a frequency control current iw from a clock generatorside, switches the frequency Fclk of a clock signal CLK generated by the clock generatorfrom a first frequency, which is comparatively high, to a second frequency, which is one or more digits lower than the first frequency, and applies the clock signal CLK to the voltage raiser. The voltage raisersaves power by performing voltage raising (charge pumping) at the second frequency.

Charge pump circuit

A high-side variable current source and a high-side transistor are provided in series between a supply power terminal of a control circuit and a gate of a switching transistor. A low-side variable current source and a low-side transistor are provided in series between the gate of the switching transistor and a ground terminal. A slew rate controller controls the current value of at least one of the high-side and low-side variable current sources according to the state of a setting terminal. A switching power supply device has a plurality of output transistors connected in parallel with one another and a controller that generates control signals turning on and off the output transistors at a predetermined frequency so as to generate a desired output voltage from an input voltage and supply the output voltage to a load. The controller determines which output transistor to drive according to the magnitude of the load.

Switching regulator control circuit, switching regulator, electronic appliance, switching power supply device, and television receiver

A charge control device includes a control circuit configured to monitor a charge voltage and a charge current of a battery and perform output feedback control upon the charge voltage and the charge current to thereby achieve constant voltage charge or constant current charge of the battery; and an adjusting circuit configured to adjust the output feedback control of the control circuit based on charge state information of the battery obtained by a gas gauge device.

Charge control device and electronic apparatus using the same

A charge control device includes a charge control circuit to control a charge of a secondary battery by controlling an output stage connected between a power supply and the secondary battery. The charge control circuit includes a first error amplifier to generate a first error voltage in response to a difference between a predetermined first reference voltage and a first feedback voltage. The value of the first feedback voltage is determined in accordance with a primary current supplied from the power supply to the output stage. The charge control circuit also includes a second error amplifier to generate a second error voltage in response to a difference between either one of a predetermined second reference voltage and the first error voltage, and a second feedback voltage. The value of the second feedback voltage is determined in accordance with a charge current supplied from the output stage to the secondary battery. The charge control circuit also includes a control signal generator to generate the control signal of the output stage in response to the second error voltage.

Charge control device and load driving device

A power supply circuit has: a DC/DC converter (M, M, L, C) which steps down an input voltage Vin to generate an output voltage Voutby rectifying and smoothing a pulsing switched voltage Vsw generated by turning on and off output switches (Mand M); and a charge pump (M-M, C, C) which steps up the input voltage Vin to generate an output voltage Voutby repeating charging and discharging of a charge accumulation capacitor (C) by turning on and off charge transfer switches (M-M). First end of the charge accumulation capacitor is connected to a terminal from which the switched voltage Vsw is outputted. The output switches are also used as part of the charge transfer switches.

Growing community of inventors

Kyoto, Japan

Tadashi Akaho