Abstract:
The present invention provides a light emitting device driver circuit and a control circuit and a control method thereof. The light emitting device driver circuit includes a power stage circuit, a feedback circuit, and a control circuit. The control circuit includes a comparison circuit, a hysteresis control circuit, and a bleeder circuit. The control circuit generates an analog control signal according to a rectified dimmer signal and an output signal, for controlling the power stage circuit to regulate an output current, which is supplied to a light emitting device circuit to determine its brightness. When the analog control signal decreases to a predetermined hysteresis low level, the light emitting device driver circuit operates in a cut-off mode wherein the bleeder circuit consumes a bleeder current so as to maintain the output current at a zero current, for keeping the light emitting device circuit OFF.
Abstract:
The present invention provides a flyback power converter, a secondary side control circuit, and a control method thereof. The flyback power converter converts an input voltage to an output voltage, and provides a load current to a load circuit. The flyback power converter includes: a transformer circuit, a power switch circuit, a switch current sense circuit, a primary side control circuit, and a secondary side control circuit. The secondary side control circuit adaptively adjusts a frequency of a zero of a compensator gain function and/or a mid-frequency gain of the compensator gain function according to the load current, such that a number of poles of a system open loop gain function of the flyback power converter is at most more than a number of zeroes of the system open loop gain function by one under a crossover frequency.
Abstract:
The present invention provides a light emitting device driver circuit and a control circuit and a control method thereof. The light emitting device driver circuit includes a power stage circuit, a feedback circuit, and a control circuit. The control circuit includes a comparison circuit, a hysteresis control circuit, and a bleeder circuit. The control circuit generates an analog control signal according to a rectified dimmer signal and an output signal, for controlling the power stage circuit to regulate an output current, which is supplied to a light emitting device circuit to determine its brightness. When the analog control signal decreases to a predetermined hysteresis low level, the light emitting device driver circuit operates in a cut-off mode wherein the bleeder circuit consumes a bleeder current so as to maintain the output current at a zero current, for keeping the light emitting device circuit OFF.
Abstract:
A power converter circuit of a low power illumination device includes a boost converter circuit, a buck converter circuit, and a control circuit, for cooperating with a dimmer and an electric transformer. The control circuit configures the boost converter circuit to alternatively operate in a current conducting mode and an off mode, to draw current from the electric transformer in the current conducting mode, and to stop drawing current from the electric transformer in the off mode. The control circuit further configures the buck converter circuit to generate the required output signals to the low power illumination device according to the configuration of the dimmer so that the low power illumination device may perform the required dimming function.
Abstract:
A power converter circuit for a low power illumination device includes a boost converter circuit, a buck converter circuit, and a control circuit. The control circuit configures the boost converter circuit to alternately operate in a current conducting mode and an off mode, to draw different values of the current from an electric transformer in different periods in the current conducting mode, and to stop drawing current from the electric transformer in the off mode. The control circuit further configures the buck converter circuit to generate the required output signals to the low power illumination device according to the output of the boost converter circuit so that the low power illumination device may function normally.
Abstract:
The present invention provides a flyback power converter, a secondary side control circuit, and a control method thereof. The flyback power converter converts an input voltage to an output voltage, and provides a load current to a load circuit. The flyback power converter includes: a transformer circuit, a power switch circuit, a switch current sense circuit, a primary side control circuit, and a secondary side control circuit. The secondary side control circuit adaptively adjusts a frequency of a zero of a compensator gain function and/or a mid-frequency gain of the compensator gain function according to the load current, such that a number of poles of a system open loop gain function of the flyback power converter is at most more than a number of zeroes of the system open loop gain function by one under a crossover frequency.