摘要:
In a voltage converter with a high-side short-circuit protection before an input voltage provided by a high-voltage power supply reaches a first threshold, a driver detects the input voltage and the output voltage of the converter to turn on the low-side transistor of the converter and turn off the high-voltage power supply when the input voltage ranges between the first threshold and a second threshold and the output voltage reaches a third threshold, to thereby avoid damages to the circuit connected to the output node of the converter. The driver comprises a front-end drive circuit to switch the high-side and low-side transistors and a low-voltage logic control circuit for the turning-on of the low-side transistor.
摘要:
A frame-shifted technique is disclosed for a dynamic gamma correction method and system that comprises counting the gray levels of each frame to figure out the probability distribution of gray levels in the current frame, and determining the gamma reference voltages according to the probability distribution of gray levels of the current frame for the gamma correction of the next frame.
摘要:
A programmable voltage supervisory circuit and method with minimum programming pins and low quiescent current is provided to monitor a supply voltage, by which only one programming pin can configure three voltage levels for the threshold voltage to be compared to the supply voltage. The programming pin is connected with a voltage select signal that is defined to be high, low or floating states each determines a setting voltage among three levels corresponding to the three threshold voltages, respectively, by a voltage select circuit. A sample/hold circuit in combination with a switch arrangement is further connected to the voltage select circuit such that the programmable voltage supervisory circuit is only operationable during the duty of a clock and thereby to reduce the power consumption thereof by squeezing the duty.
摘要:
A backlight power controller chip comprises a control circuit connected to two switches to turn on and off two display panels of a dual panel display handheld apparatus. The controller chip individually switches the two switches to control the backlight sources of the two display panels. The controller chip is available for various types of display panels.
摘要:
In a synchronized data communication on a one-wired bus, it transmits and receives a synchronizing signal that segments part of or all proportions of the data signal by use of three electrically distinguishable statuses for the identifier of the synchronizing signal and the logic states of the data signal to increase the endurance of frequency displacement and resist influences of the interference of external conditions, low quality of transmission medium, and limitation of transmission distance and make the reliability and correctness of the signal transmission improve substantially. It is also clearly illustrated the feasibility and simplicity for implementing the one-wired synchronized communication by a plurality of exemplary signal types and a transceiver circuitry.
摘要:
An inductor equivalent circuit is disclosed. The circuit comprises a reference current source, a first current mirror, a second current mirror, two operational amplifiers OP1 and OP2, a capacitor, a first transistor, a second transistor, a mirror resistor set, and a bypass current source in parallel with the capacitor. An input signal is through OP1 and second transistor to control the reference current source. The first mirror current is then feed-back a signal to the first transistor through an OP2. The current signal makes the drain current of the first transistor lags the input voltage signal by 90° due to the capacitor coupled with the first mirror current source. The mirror resistor set can be resistors having one common terminal grounded, and other terminals each, respectively, coupled with the first and the second transistor and the capacitor, or can be composed of transistors and all of them with gate property biased so that the transistors in the mirror resistor set are operated in an ohmic region. The second mirror current provides an output current of the inductor equivalent circuit for next cascade stage.
摘要:
A resistance adjustable of resistance mirror circuit having a master resistor R0, a reference current source terminal providing a current value I0 through the master resistor R0 to ground; a first transistor; a current mirror source terminal providing a current value n I0, through the first transistor to ground; an operational amplifier having a positive terminal connecting to a drain of the first transistor, a negative terminal connecting to the other terminal of the master resistor R0, and an output terminal connecting to a gate of the first transistor; a mirror resistor set composed of a plurality of transistors in parallel each other and having their source electrode connecting to ground. Each transistor of the mirror resistor set has a ratio of channel width over channel length being m-fold of that of the first transistor, where m, n is any positive numbers. Since gates of the transistors connect to the output terminal of the operational amplifier, each of the transistors therefore has an equivalent resistance Req=(1/nm)R0.
摘要:
In a gamma voltage generator and gamma voltage generating method that can tune the gamma voltages individually, several gamma currents of a same magnitude are generated for each to flow through a variable resistive element to generate a variable common voltage and several variable voltages, from which a common gamma voltage and several first gamma voltages are generated. By use of the symmetric property of the gamma curve corresponding to those gamma voltages to be generated, several voltages are generated by mapping the first gamma voltages with the common gamma voltage as the center axis, and from which several second gamma voltages are derived. The common gamma voltage and the first and second gamma voltages are provided for those gamma voltages corresponding to the gamma curve.
摘要:
The present invention discloses a power supply circuit with power factor correction (PFC) function, and an automatic gain control circuit therefor and a control method thereof. The power supply circuit includes the automatic gain control circuit and a load driver circuit. The automatic gain control circuit converts an input voltage to a regulation voltage, and the load driver circuit generates an output current according to the regulation voltage. The automatic gain control circuit automatically adjust the regulation voltage such that the regulation voltage has a substantially fixed amplitude or fixed average value under different input voltages of different specifications, and the output current provided by the load driver circuit varies in phase with the input voltage to provide a PFC function.
摘要:
The present invention discloses an active bleeder circuit capable of triggering a tri-electrode AC switch (TRIAC) circuit in all phase. The active bleeder circuit receives a rectified signal having an OFF phase and an ON phase. The active bleeder includes: a detection circuit for generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase of the rectified signal; and a current sinker circuit coupled to the detection circuit, for generates a latching current to trigger the TRIAC circuit by operating a switch when the detection signal exceeds a predetermined level. The present invention also discloses a light emitting device power supply circuit and a TRIAC control method using the active bleeder circuit.