Aimtron Technology Corp.

Global Mixed-mode Technology Inc.

Tien-Tzu Chen

Guang-Nan Tzeng

Chi-Yang Chen

Fang-Te Su

Chia-Hung Tsen

Yu-Ming Tsai

Yung-Chih Chen

Li-Cheng Chen

Ching-Kun Lin

Shang-Yu Chang Chien

A LED dimming control circuit that avoids a higher output voltage than expected is provided. The LED dimming control circuit comprises an inductor, a transistor, a dimming control signal, a feedback signal, a switching control circuit, an error amplifier, and an inverted amplifier. The inductor and the transistor are coupled to a node. The switching control circuit is controlled by the dimming control signal and the feedback signal. The transistor is controlled by the switching control circuit. The output terminal of the error amplifier and the non-inverted input terminal of the error amplifier form a negative feedback path via the inverted amplifier.

LED dimming control circuit

A synchronous switching voltage converter has a first switch, a second switch, and an inductor, which are all coupled together to a switch node. A reverse current preventing circuit has a current detecting circuit, a voltage detecting circuit, a delay time adjusting circuit, and a blocking circuit. When an inductor current reduces to reach a predetermined threshold current, the current detecting circuit generates an original preventing signal. The voltage detecting circuit detects a switch voltage at the switch node. In response to the original preventing signal, the delay time adjusting circuit generates a corrected preventing signal after an adjustable delay time with respect to the original preventing signal. The adjustable delay time is adjusted on a basis of the switch voltage. In response to the corrected preventing signal, the blocking circuit turns OFF the second switch.

Reverse current preventing circuit and method

An initial voltage establishing circuit has a current supplying circuit, a current adjusting circuit, a charge/discharge control circuit, and an oscillating signal generating circuit. The current supplying circuit provides a charge current and a discharge current. The current adjusting circuit adjusts the charge current and the discharge current. The charge/discharge control circuit selectively allows the charge current and the discharge current to flow through. The oscillating signal generating circuit employs the charge current and the discharge current to generate an initial voltage establishing signal such that a duty cycle of the initial voltage establishing signal gradually increases. The initial voltage establishing signal is applied to a switching voltage converter for establishing an initial output voltage.

Initial voltage establishing circuit for a switching voltage converter

A switching voltage regulator has a first switch, a second switch, and an inductor, which are coupled together to a switch node. A switch control system applies a drive signal for controlling the first and the second switches. A duty cycle detecting circuit detects a duty cycle of the drive signal. When the duty cycle is larger than a predetermined threshold, the duty cycle detecting circuit generates an over-threshold signal. When the duty cycle is smaller than the predetermined threshold, the duty cycle detecting circuit generates an under-threshold signal. In response to the over-threshold signal and the under-threshold signal, an oscillating signal adjusting circuit generates an adjusting current. An oscillating signal generating circuit generates and applies an oscillating signal to the switch control system. The oscillating signal has a period adjusted by the adjusting current.

Switching voltage regulator with an improved range of input voltage

Through operated alternately between a charging phase and a discharging phase, a charge pump converts an input voltage source into a drive voltage for being supplied to a light emitting diode. A current setting unit determines a reference current. A current regulating unit has a current regulating terminal and a feedback detecting terminal. The current regulating terminal is coupled to the light emitting diode so as to control a current flowing through the light emitting diode to be proportional to the reference current. The feedback detecting terminal provides a feedback signal representative of a current regulation characteristic voltage. Based on a difference between the feedback signal and a reference voltage source, an error amplifier generates an error signal. A variable resistance unit is coupled between the input voltage source and the charge pump for adjusting a variable resistance in response to the error signal.

Charge pump drive circuit for a light emitting diode

A switching circuit operates with a first operating state and a second operating state. During the first operating state, the switching circuit allows a switching current to linearly increase. During the second operating state, the switching circuit allows the switching current to linearly decrease. A control circuit is coupled to the switching circuit for controlling the switching circuit to operate with the first operating state or the second operating state. A setting circuit generates a threshold signal for the control circuit to ensure that during the first operating state the switching current linearly increases to become higher than or equal to a current value set by the threshold signal. Thereby, the switching current is prevented from linearly decreasing to reverse polarity during the second operating state.

Switching voltage regulator operating without a discontinuous mode

An input switching unit selectively couples a first terminal of an inductor with an input voltage and a ground potential. An output switching unit selectively couples a second terminal of the inductor with an output voltage and the ground potential. A first pulse generating circuit generates a first pulse signal with a first duty ratio, which is modulated in response to the output voltage. A second pulse generating circuit generates a second pulse signal with a second pulse signal with a second duty ratio, which is a constant larger than zero and smaller than one. When the first duty ratio is larger than a predetermined threshold duty ratio, a mode control circuit applies the first pulse signal to control one of the input switching unit and the output switching unit and applies the second pulse signal to control another of the input switching unit and the output switching unit.

Buck-boost voltage converter

A light loading control circuit operates a switching circuit of a buck-boost voltage converter alternately in a plurality of phase cycles and a sleep period. Each phase cycle has a rising phase, a falling phase, and a maintaining phase. In the rising phase, the switching circuit is operated to increase an inductor current. In the falling phase, the switching circuit is operated to decrease the inductor current. In the maintaining phase, the switching circuit is operated to keep the inductor current approximately constant. The sleep period prevents two terminals of an inductor from being respectively coupled to two selected from a group consisting of an input voltage, an output voltage, and a ground potential.

Light loading control circuit for a buck-boost voltage converter

A drive circuit applies a drive voltage through an outputs terminal to a switching element. The drive circuit includes a supplying circuit, an amplifying circuit, a detecting circuit, and an adjusting circuit. In response to a control signal, the supplying circuit generates a first drive current. The amplifying circuit generates and applies a second drive current, which is larger than the first drive current, to the output terminal for changing the drive voltage. The detecting circuit is coupled to the output terminal for generating a detection signal representative of the drive voltage. Based on the detection signal, the adjusting circuit implemented by a differential comparator dynamically adjusts the first drive current.

Drive circuit for a switching element

A light-load power transistor and a heavy-load power transistor are connected in parallel between an input voltage and an output voltage. The light-load power transistor has a smaller current driving capability, i.e. a smaller dimension of a current path. During a light-load mode, only is the light-load power transistor activated to reduce the current consumption caused by an error amplifier, thereby enhancing the efficiency. When a detection current signal is higher than a threshold current signal, the heavy-load power transistor is additionally activated through a gate control circuit by a mode selection circuit, thereby achieving a sufficient current driving capability.

Linear voltage regulator with selectable light and heavy load paths

A voltage detection unit generates a detection voltage signal representative of a potential difference caused by a current to be detected. A reference current generation unit generates a first reference current and a second reference current having a linear relationship therebetween. In response to the detection voltage signal and the first reference current, a transfer unit determines a first operation voltage. Furthermore, the transfer unit determines a second operation voltage and a transfer current in response to the first operation voltage and the second reference current. The second operation voltage is substantially equal to the first operation voltage. A detection current signal having a linear relationship with the current to be detected is generated through subtracting at least the second reference current from the transfer current.

Current sensing circuit

A charge pump is driven by at least one clock signal, for converting a supply voltage source into a pumping voltage. The pumping voltage is a function of an amplitude of the at least one clock signal such that an absolute value of the pumping voltage is larger when the amplitude of the at least one clock signal is larger. The amplitude of the at least one clock signal is so modulated as to gradually change from an activation value during an amplitude modulation period. The amplitude modulation period lasts longer than a period of the at least one clock signal by one or more metric orders. The charge pump is activated by the at least one clock signal with the amplitude of the activation value. Thereafter, the charge pump is controlled in such a way that the absolute value of the pumping voltage gradually changes along with the modulation of the amplitude of the at least one clock signal.

Soft-start charge pump circuit

First and second clocks are applied to first and second capacitors, respectively. First and second former-stage clocks are applied to first and second former-stage capacitors, respectively. A first switch couples the second former-stage capacitor with the first capacitor. A second switch couples the first former-stage capacitor with the second capacitor. A first reverse current preventing circuit couples a control electrode of the first switch alternately with the second capacitor and the second former-stage capacitor. A second reverse current preventing circuit couples a control electrode of the second switch alternately with the first capacitor and the first former-stage capacitor. Falling edges of the first and second clocks occur earlier than falling edges of the first and second former-stage clocks, respectively. Rising edges of the first and second former-stage clocks occur earlier than rising edges of the first and second clocks, respectively.

High efficiency charge pump with prevention from reverse current

A switching DC-to-DC converter includes multiple power supply channels, coupled in parallel between a DC voltage source and ground, for converting the DC voltage source into multiple DC output voltages that are separate from each other. An oscillator outputs multiple oscillating signals to render each of the multiple power supply channels make at least one switching transition differently in the time domain from others of the multiple power supply channels, thereby improving transient noise. The multiple oscillating signals include two triangular wave signals with a phase difference of 180 degrees and two pulse wave signals with a-phase difference of 180 degrees. Rising edges of the two pulse wave signals occur simultaneously with either a peak or a valley of the two triangular wave signals, respectively.

Switching DC-to-DC converter with multiple output voltages

A first oscillating signal presenting a peak, a valley, a rising portion gradually increasing from the valley to the peak, and a falling portion gradually decreasing from the peak to the valley is generated. A second oscillating signal presenting an instantly transiting edge, which occurs simultaneously with either the peak or the valley of the first oscillating signal, is generated. The first and the second oscillating signals are input to a first and a second power supply channels, respectively, for converting a DC voltage source into two separate DC output voltages. The first and the second oscillating signals cause at least one switching transition of the first power supply channel to occur separately in the time domain from at least one switching transition of the second power supply channel, thereby preventing transient spikes from superposing together.

Growing community of inventors

Hsinchu, Taiwan

Tien-Tzu Chen