Aimtron Technology Corp.

Global Mixed-Mode Technology Inc.

Rong-Chin Lee

Guang-Nan Tzeng

Yung-Chih Chen

Li-Cheng Chen

Fang-Te Su

Ching-Kun Lin

Ching-Sung Wu

An overvoltage protection circuit which can be applied to a motor controller is provided. The overvoltage protection circuit is coupled to an input terminal for receiving an input voltage. The overvoltage protection circuit comprises a switch circuit, a controller, and a comparing unit. When the input voltage is greater than a first voltage, a discharging mechanism is forced to start so as to suppress a voltage spike. When the input voltage is less than a second voltage, the discharging mechanism is closed so as to operate normally.

Overvoltage protection circuit

A motor controller comprises a driving circuit, a selection circuit, a sensorless control circuit, a Hall signal control circuit, a detection circuit, a first input terminal, and a second input terminal. The Hall signal control circuit may be coupled to a Hall sensor via the first input terminal and the second input terminal. When each of the voltage of the first input terminal and the voltage of the second input terminal is at a low level, the motor controller is operated in a sensorless driving mode. When one of the voltage of the first input terminal and the voltage of the second input terminal is at a high level, the motor controller is operated in a Hall control driving mode.

Motor controller

A motor controller is configured to stabilize a motor current. The motor controller is used for driving a motor, where the motor has a motor coil. The motor controller comprises a switch circuit, a control unit, a command unit, a counting unit, a comparing unit, and a phase detecting unit. The switch circuit is used for supplying the motor current to the motor coil. The phase detecting unit generates a phase signal to the control unit, so as to inform the control unit to switch phases. The control unit generates a plurality of control signals to control the switch circuit. The motor controller resets the counting unit based on the phase signal, such that the control signals are synchronized with the phase signal for stabilizing the motor current.

A voltage converting circuit has an output terminal for supplying an output current at an output voltage to a load. In response to a transient of the load, a current sinking circuit allows a current source to provide a sink current flowing from the output terminal of the voltage converting circuit into a ground potential. The sink current is finite and stable. When the output voltage decreases below a threshold voltage, the current sinking circuit allows the current source to keep providing the finite and stable sink current for an extension time, causing the output voltage to decrease from the threshold voltage to a regulated value.

Voltage regulator with prevention from overvoltage at load transients

When a primary winding current increases to an upper limit determined by a reference voltage having a soft-start characteristic, a power switch is turned OFF. When a secondary winding current decreases to a lower limit determined by another predetermined reference voltage, the power switch is turned ON. A minimum ON-time limiting unit prevents the power switch from being turned OFF before a minimum ON-time expires. The minimum ON-time may be provided with a soft-start modulation. A minimum OFF-time limiting unit prevents the power switch from being turned ON before a minimum OFF-time expires. A maximum ON-time limiting unit prevents the power switch from still remaining ON after a maximum ON-time expires.

Capacitor charging circuit with a soft-start function

A dimming control circuit generates a dimming control signal for determining brightness of at least one light-emitting diode. The dimming control signal has a plurality of bright-dark cycles, each of which consists of a bright phase and a dark phase. The bright phase starts with an adaptive rising portion. The adaptive rising portion restricts the brightness of the at least one light-emitting diode to increase gradually from zero.

Dimming control circuit for light-emitting diodes

In a pulse frequency modulated (PFM) voltage regulator, a PFM switching signal is provided for converting a DC voltage source to an output voltage. The output voltage is detected. When the output voltage is lower than a predetermined target voltage, a duty cycle of the PFM switching signal is reduced. For example, a minimum OFF-time of the PFM switching signal may be prolonged or a constant ON-time of the PFM switching signal may be shortened. In other words, a period of delivering energy to a capacitor from an inductor may be prolonged or a period of storing energy in the inductor may be shortened. Therefore, a ripple of the output voltage is effectively reduced when the PFM voltage regulator is operated in a heavy loading condition.

Method of reducing a ripple of a heavy loading pulse frequency modulated voltage regulator

In a pulse frequency modulated (PFM) voltage regulator, a PFM switching controller is provided to generate a PFM switching signal for converting a DC voltage source to an output voltage. A minimum OFF-time controller provides the PFM switching signal with a minimum OFF-time. In response to the output voltage, a feedback circuit generates a feedback signal. When the output voltage is lower than a predetermined target voltage, an OFF-time prolonging circuit prolongs the minimum OFF-time in response to the feedback signal. In other words, a time of delivering energy to a capacitor from an inductor may be prolonged by the OFF-time prolonging circuit. Therefore, a ripple of the output voltage is effectively reduced when the PFM voltage regulator is operated in a heavy loading condition.

Pulse frequency modulated voltage regulator capable of prolonging a minimum off-time

A motor control circuit includes a forward rotation control circuit, a reverse rotation control circuit, and a brake control circuit. The forward rotation control circuit allows a first current source to supply a first current signal to a motor drive circuit for operating a motor in a forward rotation mode. The reverse rotation control circuit allows a third current source to supply a third current signal to the motor drive circuit for operating the motor in a reverse rotation mode. The brake control circuit allows a second current source and a fourth current source to respectively supply a second current signal and a fourth current signal to the motor drive circuit for operating the motor in a brake mode. The motor control circuit reduces power dissipation in the brake mode since the second and fourth current signals may be smaller than the first and third current signals.

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Pingtung County, Taiwan

Rong-Chin Lee