摘要:
A dual mode charge pump is operable in a first mode or a second mode for providing positive and negative output voltages that can be stabilized by adjusting the charging time of two terminals of a flying capacitor or by adjusting the charging/discharging time of the positive and negative voltage output terminals. The dual mode charge pump can apply to a much wider input supply voltage range with less numbers of power switches, thus requiring less die area and lower costs. Moreover, the dual mode charge pump can precisely define a common mode voltage, thus making the common voltage drift smaller and less load dependent, especially when the output supply voltages are under different load conditions.
摘要:
A LED driver is disclosed for providing a current for LED lighting. The LED driver includes an inductor and a controller having a power switch, and the inductor, the power switch and a LED to be driven are configured to be an asynchronous boost converter. Because the driven LED serves as a rectifier diode of the asynchronous boost converter, the controller may have fewer components and requires smaller die area.
摘要:
A plurality of switches, an inductor and two capacitors are configured to be a boost-inverting converter. To operate the converter in a boost-inverting mode, a control apparatus and method switch the switches such that the inductor is energized in a first phase, the first capacitor is discharged to produce an inverting voltage in a second phase, and the capacitor Cout1 is discharged to produce the inverting voltage and the second capacitor is charged to produce a boost voltage in a third phase. Therefore, the boost-inverting converter has lower peak inductor current and less power loss, and the limitation to the switch design for the boost-inverting converter is relaxed.
摘要:
A voltage generating circuit, which generates tri-state logic output in accordance with high, low or floating of the input node, is proposed. The present voltage generating circuit includes: a pulse generating circuit for generating a plurality of pulses; a voltage selecting circuit having a pair of NMOS transistors coupled in common source, each drain of the NMOS transistors is coupled to a current source respectively, both gates of the NMOS transistors are coupled to an input node, and the paired drain of the NMOS transistors generate a pair of voltage output; a plurality of flip-flops, which couple to drains of the NMOS transistors to lock the voltage output of the NMOS transistors in accordance with the pulses; an inner voltage-generating unit couples to the input node for providing a floating voltage level; and a plurality of switches controlled by the pulses for controlling the normal operation of the voltage selecting circuit and the conduction between the inner-voltage generating unit with the input node.
摘要:
A driver circuit for a DC light source supplies a voltage generated by a DC-to-DC converter for a plurality of lamp strings connected in parallel and a plurality of driving currents generated by a current mirror for the lamp strings, such that the lamp strings may have well controlled or uniform brightness.
摘要:
The invention provides an output control apparatus for adjusting the output level of a pulse width modulation (PWM) signal by changing the amplitude level of the output PWM signal. The output control apparatus comprises a control signal generator, a digital-to-analog converter (DAC), and an output circuit. The control signal generator generates a digital control signal. The DAC outputs a predetermined level according to the digital control signal. The output circuit with a negative feedback loop receives the PWM signal and receives the predetermined level by the negative feedback loop. While the PWM signal is logic number “0”, the negative feedback loop is not switched on, so as to control the level of the PWM signal at a base level. While the PWM signal is logic number “1”, the negative feedback loop is switched on, so as to control the level of the PWM signal at the predetermined level.
摘要:
A control device, which controls a power-converting module that is coupled to a light-emitting component, includes a duration detecting unit and a control signal generator. The duration detecting unit compares the duration of a predetermined logic state of a pulsating input dim control signal with a reference time period. The control signal generator is enabled by the duration detecting unit so as to generate a control signal that enables the power-converting module to generate a drive voltage for driving the light-emitting component when the duration of the predetermined logic state is not longer than the reference time period. The duration detecting unit disables the control signal generator to disable the power-converting module when the duration of the predetermined logic state is longer than the reference time period.
摘要:
A voltage generating circuit, which generates tri-state logic output in accordance with high, low or floating of the input node, is proposed. The present voltage generating circuit includes: a pulse generating circuit for generating a plurality of pulses; a voltage selecting circuit having a pair of NMOS transistors coupled in common source, each drain of the NMOS transistors is coupled to a current source respectively, both gates of the NMOS transistors are coupled to an input node, and the paired drain of the NMOS transistors generate a pair of voltage output; a plurality of flip-flops, which couple to drains of the NMOS transistors to lock the voltage output of the NMOS transistors in accordance with the pulses; an inner voltage-generating unit couples to the input node for providing a floating voltage level; and a plurality of switches controlled by the pulses for controlling the normal operation of the voltage selecting circuit and the conduction between the inner-voltage generating unit with the input node.
摘要:
A dimming method for LED driving circuit is proposed. By temporary switching a pin that is originally used for the input/output of other electric signals to a high impedance node, the dimming control signal may be inputted to dim LEDs. The dimming method comprises the steps of: floating the pin every a period of time to pull the pin's voltage being equal to the dimming control signal; detecting the pin's voltage; and retrieving the dimming control signal in accordance with the detected pin's voltage and thereafter dimming the LEDs.
摘要:
A dimming method for LED driving circuit is proposed. By temporary switching a pin that is originally used for the input/output of other electric signals to a high impedance node, the dimming control signal may be inputted to dim LEDs. The dimming method comprises the steps of: floating the pin every a period of time to pull the pin's voltage being equal to the dimming control signal; detecting the pin's voltage; and retrieving the dimming control signal in accordance with the detected pin's voltage and thereafter dimming the LEDs.