Princeton Technology Corporation

Ming-Yuan Tsao

Shih-Chou Kuo

Ko-Han Chen

Chiung-Hung Chen

Dang-Ching Lin

Mean-Sea Tsay

An LED driving method is provided. The method includes the steps of: receiving a brightness control signal, wherein the brightness control signal represents a duty cycle of an LED within a pulse width modulation cycle, and the duty cycle is indicated by a plurality of illuminating clocks; dividing the PWM cycle into a plurality of sub-PWM cycles; and equally distributing the illuminating clocks to each of the sub-PWM cycles.

Method and apparatus for driving light emitting diode

A relaxation oscillator includes a first amplifier having a first input terminal receiving an output voltage signal, a second input terminal receiving a reference voltage signal, and an output terminal comparing the output voltage signal and the reference voltage signal and in response thereto outputting a control signal; a second amplifier having a first input terminal receiving the output voltage signal, a second input terminal connected to the output terminal of the first amplifier for receiving the control signal, and an output terminal connected to the first input terminal of the first amplifier and the first input terminal of the second amplifier for comparing the control signal and the output voltage signal and in response thereto outputting the output voltage signal; and a sensing capacitor for generating the output voltage signal by charging/discharging operations by the output terminal of the second amplifier.

Relaxation oscillator

An LED driving device has a first constant current source circuit and a voltage control circuit. The first constant current source outputs a first constant current to a first node and the first constant current flows into a first LED module disposed between a driving node and the first node; wherein, the first constant current source circuit has a first detection node for generating a first detection signal in response to the voltage level of the first node. The voltage control circuit is coupled to the first detection node, for outputting a control signal in response to the first detection signal to a voltage regulator circuit in order to control and modulate the voltage regulator circuit to output a driving voltage to the driving node.

LED driving device

A LED driving apparatus includes: an output transistor, having a drain coupled to the LED; a node, coupled to a source of the output transistor; a ground transistor, having a drain coupled to the node, and a source coupled to the ground; an operational amplifier, including: a first input end and a second input end, for respectively receiving a driving signal and a feedback signal; and an output end, for outputting an output signal to a gate of the output transistor; a compensating capacitor, including a first end and a second end; and a switching unit, for switching between a first connection mode and a second connection mode, so as to offset a bias difference to the node for compensating the bias difference of the operational amplifier.

LED driver apparatus

A power-on reset circuit has a first impedance device, a first switch device, a first capacitor, a second switch device, a third switch device, a fourth switch device, a second impedance device, a second capacitor, and a control circuit coupled to a reset input terminal of a circuit device. When the power-on reset circuit is supplied with electric power, the first switch device and the third switch device are turned on and the second switch device and the fourth switch device are turned off. When the electric power is removed from the power-on reset circuit, the first switch device and the third switch device are turned off and the second switch device and the fourth switch device are turned on. The second capacitor is discharged through the fourth switch to a voltage level being close to a ground voltage.

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Taipei, Taiwan

Ming-Yuan Tsao