Renesas Technology Corp.

Renesas Electronics Corporation

Hitachi, Ltd.

Renesas Electronics America Inc.

Shin Chiba

Ryotaro Kudo

Toshio Nagasawa

Koji Tateno

Kyoichi Hosokawa

Koji Saikusa

Yoshitaka Onaya

Tetsuo Sato

Hideo Ishii

Jin Kiong Ang

Matsuura Nobuyoshi

A power-supply apparatus according to an aspect includes an inductor, a transistor that supplies, in an on-state, a current to the input side of the inductor, a second transistor that becomes, when the first transistor is in an off-state, an on-state and thereby brings the input side of the inductor to a predetermined potential, a signal generation unit that generates voltage signals corresponding to a current flowing to the inductor, an amplifier that outputs a current according to the voltage signals, a converter that converts the current output from the amplifier into a voltage signal, and a control unit that controls the transistors based on a first feedback signal corresponding to the voltage on the output side of the inductor and the voltage signal, which is used as a second feedback signal.

Power-supply apparatus having a high-side transistor and a low-side transistor

Power-supply apparatus

A method can include obtaining a voltage across a first transistor as an obtained voltage. The method can also include multiplying the obtained voltage by a predetermined multiple M to yield a multiplied voltage. The method can further include applying the multiplied voltage to a second transistor, wherein the second transistor is N times smaller than the first transistor. The method can additionally include providing an output current of the second transistor as an M/N scaled estimate of an output current of the first transistor.

Current sensing and measuring method and apparatus

In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor, and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Power supply device and switching power supply device

In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

In order to decrease a change in the offset caused by high-frequency noise, filter circuits for cutting high-frequency noise are inserted between the input terminals of a differential amplifier circuit and input nodes of a differential amplifier stage, the filter circuits having a cut-off frequency which is higher than a cut-off frequency of the differential amplifier circuit but is lower than a cut-off frequency of a parasitic filter circuit constituted by a parasitic capacity and a parasitic resistance in the input unit.

Semiconductor integrated circuit device

Growing community of inventors

Takasaki, Japan

Shin Chiba