Fujitsu Corporation

Fujitsu Semiconductor Limited

Fujitsu Microelectronics Limited

Spansion Llc.

Morihito Hasegawa

Hidekiyo Ozawa

Takashi Matsumoto

Ryuta Nagai

Hidenobu Ito

Chikara Tsuchiya

Toshihiko Kasai

Kwok Fai Hui

Shoji Tajiri

Shinji Saito

Katsuyuki Yasukouchi

Toru Nakamura

Satoshi Katayama

Yat Fong Yung

Masanori Kishi

According to one aspect of the embodiment, a linear regulator circuit includes an output transistor outputting an output current based on a input voltage, an error amplifier outputting a control signal based on an electric potential difference between an output voltage based on the output current and a reference voltage, a buffer circuit coupled between the error amplifier and the output transistor, and a drive capability adjustment circuit adjusting a load drive capability of the buffer circuit in synchronization with the output current.

Linear drop-out regulator circuit

In the following B cycles, the second frequency-divided signal fA is maintained at a low level, while the third frequency-divided signal fB is maintained at a high level. The three-modulus prescalerhas a frequency division value (M&#x2212;1) if the pseudo random values are negative values, and a frequency division value (M+1) if the pseudo random values are positive values, in accordance with the signs of the pseudo random values outputted from the &#x3a3;&#x394; modulator. After that, the frequency division value becomes M. A frequency division value of (MN+A+Bx) including the pseudo random value Bx is obtained in the comparison frequency divider. A fractional frequency division operation can be realized through &#x3a3;&#x394; modulation by using the pseudo random numbers including negative values, as they are.

Fractional frequency divider PLL device and control method thereof

A DC-DC converter prevents localization of switching operations at light loads and is able to improve power conversion efficiency. The DC-DC converter of some variations performs pulse frequency modulation control at light loads, and includes a reducing circuit configured to skip an oscillation frequency signal at light loads and to generate a skipped signal.

DC-DC converter for pulse frequency modulation control and power supply system

A power supply circuit includes an output transistor including a source coupled to power supply voltage, and a drain from which output voltage is outputted; a first error amplifier powered by the power supply voltage and outputting a signal based on a potential difference between the output voltage and a reference voltage; a buffer transistor including a gate coupled to the output of the first error amplifier, and a source coupled via a constant current source to the power supply voltage and coupled to a gate of the output transistor; a current detection transistor coupled to the output transistor such that a gate and source are shared; and an overcurrent protection circuit configured to limit the drain current of the buffer transistor based on the increase of the drain current of the current detection transistor and thereby control the output current of the output transistor.

Power supply circuit, overcurrent protection circuit for the same, and electronic device

A DC-DC conversion circuit is configured by including a plurality of control signal generation circuits, a plurality of soft-start control circuits, and a start control circuit. The plurality of control signal generation circuits correspond to the plurality of control signals, and generate a corresponding control signal of the plurality of control signals based on a corresponding output value of a plurality of output values. The plurality of soft-start control circuits correspond to the plurality of control signals, and control a variation of the corresponding control signal at a start time of the DC-DC conversion circuit. The start control circuit instructs the corresponding soft-start control circuit to start operation in accordance with a change of the control signal taking part in an output control at the start time of the DC-DC conversion circuit.

DC-DC converter with a plurality of soft-start control circuits

The control circuit comprises: a detecting portion COMPfor detecting a status transition of a first signal FR at the connecting point P which changes at a constant cycle corresponding to current flowing through the antiparallel diode D when the main switch device FET is turned OFF; and a phase difference adjusting portionfor adjusting the phase difference by adjusting the output timing of the second signal FP corresponding to a phase difference between the phase of the first signal FR detected by the detecting portion COMPand the phase of the second signal FP generated based on the first signal of one cycle before and the rectification switch device FETis turned ON corresponding to the second signal FP whose output timing is adjusted by the phase difference adjusting portion

Control circuit of synchronous rectification type power supply unit, synchronous rectification type power supply unit and control method thereof

The control circuitof power supply unit and power supply unitcontrolling output power with electric power supplied from the external power, comprise a monitoring portionmonitoring current Iand voltage outputted from the external power supplyand output power of the external power supplyand a setting portion ewhich sets an upper limit value of current outputted from the external power supplybased on a monitoring result of the monitoring portion

Control circuit of power supply unit which controls output power of external power supply based upon current from the external power supply, power supply unit and control method thereof

A first power supply line and having a first conductivity type a second transistor coupled between the first transistor and a second power supply line, and having the first conductivity type an output unit driving a first control signal causing the first transistor to become conductive, based on a drive voltage, and outputting the first control signal to the first transistor and a boot strap circuit including a capacitor having a first end coupled to a node of the first transistor and the second transistor and supplying the output unit with the drive voltage based on the capacitor, wherein an electric potential of the first end is reduced before the first transistor becomes conductive.

DC-DC converter and control method thereof

According to one aspect of the invention, a DC-DC converter including a soft-start function of a soft start in response to a soft-start signal, comprises: a detection circuit that detects whether the soft-start signal is active at an end of a soft-start operation; and an output voltage control circuit that controls an output voltage based on detection result of the detection circuit.

DC-DC converter, power supply voltage supplying method, and power supply voltage supplying system

A DC-DC converter for preventing through current from causing erroneous operation of an ideal diode. A first transistor for receiving input voltage is connected to an ideal diode, which includes a second transistor and a comparator for detecting current flowing through the second transistor and generating a detection signal. A control circuit generates a switching signal for turning the first transistor on and off so as to keep the output voltage constant. A pulse generation circuit generates a pulse signal for turning off the second transistor before the first transistor is turned on and keeping the second transistor turned off for a predetermined period from when the first transistor is turned on. An erroneous operation prevention circuit generates a control signal for keeping the second transistor turned off from when the second transistor is turned off to when the first transistor is turned on.

Circuit for preventing through current in DC-DC converter

To provide a control circuit for a synchronous rectifier-type DC-DC converter, a synchronous rectifier-type DC-DC converter and a control method thereof in which, in a light load state and a no-load state, an output voltage can be dropped to thus prevent an overshoot state from continuing. A synchronous rectifier-type DC-DC converterand a control circuitA thereof comprising a first switching element FETthat is made conductive when power is accumulated in an induction element L, and a second switching element FETthat is made conductive when power accumulated in induction element Lis supplied to a load, also comprises a detecting unit COMPthat detects that a value of an output voltage VOUT of the synchronous rectifier-type DC-DC converterA is a predetermined voltage value that is higher than a target voltage value, and control units COMPand ORthat maintain the second switching element FETin a conductive state after discharge of the power accumulated in the induction element Lis finished, based on the detection results of the detecting unit COMP

Control circuit for synchronous rectifier-type DC-DC converter, synchronous rectifier-type DC-DC converter and control method thereof

A DC-DC converter reducing reverse current and maintaining high conversion efficiency under a light load. The DC-DC converter perform pulse width modulation (PWM) or pulse frequency modulation (PFM) and includes a drive control circuit generating a first drive signal and a second drive signal activating and inactivating a first transistor and a second transistor in a complementary manner. A reversed flow detection circuit detects current flowing to the second transistor and generates a detection signal controlling activation and inactivation of the second transistor. A detection signal invalidation circuit, coupled to the reversed flow detection circuit and the drive control circuit, receiving an operation switch signal and invalidating the detection signal in response to the operation switch signal during at least a certain period of the PWM.

Control circuit for detecting a reverse current in a DC-DC converter

It is intended to provide a control circuit of power supply, a power supply and a control method thereof capable of achieving power saving in an integrated circuit and reducing a delay time of the integrated circuit. The control circuitof a power supplywhich outputs plural DC voltages VCC, VBGP, VBGN each having a different voltage value includes a voltage changing portion SWwhich detects an output current Irelating to a first DC voltage VCC which is one of the plural DC voltages and sets at least one DC voltage except the first DC voltage VCC based on the detected output current I, and the like.

Control circuit of power supply, power supply and control method thereof

A DC-DC converter prevents through current from flowing in an output transistor. A first transistor receives an input voltage. A second transistor is connected to the first transistor. A comparator is connected to the second transistor. The comparator detects current flowing through a choke coil based on the potential difference between two terminals of the second transistor to generate a switching control signal for turning the second transistor on and off. The second transistor and the comparator form an ideal diode. A control circuit of the DC-DC converter generates an activation signal for turning the first transistor on and off based on a pulse signal to keep an output voltage constant. A through current prevention pulse generation circuit generates a pulse signal for turning off the second transistor from before the first transistor is turned on to after the first transistor is turned on.

DC-DC converter and control circuit for DC-DC converter

To provide a control circuit of a current mode DC-DC converter, a current mode DC-DC converter and a control method thereof having excellent high-speed responsiveness with respect to fluctuations in output voltage. The control circuit of the current mode DC-DC converter serves as a DC-DC converterthat controls a peak value of a coil current and comprises a window comparator that detects whether an output voltage VOUT is within a predetermined voltage range including a target voltage, and a peak current setting unit that sets a peak current setting value of a coil current to a lower limit value or an upper limit value in response to a high or low voltage level of the output voltage VOUT, in the case that the output voltage VOUT is not within the predetermined voltage range including the target voltage.

Growing community of inventors

Kasugai, Japan

Morihito Hasegawa