Abstract: A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.

Abstract: A VCOM generator circuit generates a VCOM signal for an electronic display. The VCOM circuit includes an operational amplifier having reduced supply rails. In an implementation, the VCOM circuit has at least three supply rails, AVDD, ground or GND, and VP or VN, or both. VP is less than AVDD and greater than VN. VN is higher than ground and below VP. The VCOM circuit with reduced voltage supply rails for VP and VN reduces power consumption of the VCOM op amps. By reducing power consumption, this also reduces the surface temperature of the integrated circuit.

Abstract: A voltage converter includes a low dropout regulator voltage converter circuit. The voltage converter generates three voltages (e.g., 1.2 volts, 2.5 volts, and 1.8 volts) for an electronic system, which can be a smartphone or electronic tablet or other device. An implementation has at least one charge pump voltage converter circuit. The low dropout regulator voltage converter circuit provides an output voltage based on its input voltages and can operate with a very small input-to-output differential voltage. Compared to using a Buck converter, a low dropout regulator does not have an external inductor, which saves space. An implementation of the voltage converter can also include at least one charge pump voltage converter circuit to generate a voltage of the voltage converter.

Abstract: One or more resistors or resistances are integrated in a 7-bit DVR or PVCOM integrated circuit. A 7-bit DVR or PVCOM integrated circuit includes a 7-bit DAC. The integrated resistors or resistances (R1, R2, or RSET, or any combination) reduces the number of external components, reduces the number of pins, and increases the accuracy of the DVR or PVCOM circuit. The least significant bit (LSB) of the DAC depends only on ratios of internal resistors, which can be made very accurate and independent of temperature.

Abstract: An LED lighting system includes a luminescent unit driven by a rectified AC voltage and a bleeder circuit. The bleeder circuit includes a current source, a dimming detection unit and an adjusting unit. The current source is configured to provide a bleeder current according to a control signal. The dimming detection unit is configured to monitor the rectified AC voltage, thereby outputting a dimming detection signal associated with an operational mode of the LED lighting system. The adjusting unit is configured to output the control signal according to the dimming detection signal so as to instruct the current source to keep the bleeder current at a first value during a first period and at a second value smaller than the first value during a second period subsequent to the first period when the dimming detection signal indicates that the LED lighting system is operating in a dimming mode.

Abstract: An LED lighting system includes a luminescent unit driven by a rectified AC voltage, a dimmer switch configured to adjust a duty cycle of a system current, and a bleeder circuit. The bleeder circuit includes a first current source, a second current source, a third current source, a current-sensing element for providing a first feedback voltage associated with the system current, a capacitor, and a control unit. The control unit is configured to activate the first current source and deactivate the second current source for charging the capacitor when the system current exceeds a predetermined threshold, deactivate the first current source and activate the second current source for discharging the capacitor when the system current does not exceed the predetermined threshold, and deactivate the third current source to stop supplying the bleeder current according to a second feedback voltage established across the capacitor.

Abstract: A technique analyzes an image to be displayed on a screen, before it is displayed, to determine a current draw of that image on the screen. Based on this analysis, adjustments can be made to the circuitry so that when the image is displayed, it is done so more efficiently. In a specific implementation, a DC-to-DC converter includes two boost converter circuits. Based on the analyzed image, the technique turns on a single boost converter when the current draw of that image is below an identified current threshold level, and turns on two boost converters when above the identified current threshold level.

Abstract: An LED lighting system includes a luminescent unit driven by a rectified AC voltage, a dimmer switch configured to adjusting a duty cycle of a system current, and a bleeder circuit. The bleeder circuit includes a first current source, a second current source, a third current source, a current-sensing element for providing a first feedback voltage associated with the system current, a capacitor, and a control unit. The control unit is configured to activate the first current source and deactivate the second current source for charging the capacitor when the system current exceeds a predetermined threshold, deactivate the first current source and activate the second current source for discharging the capacitor when the system current does not exceed the predetermined threshold, and deactivate the third current source to stop supplying the bleeder current according to a second feedback voltage established across the capacitor.

Abstract: An LED lighting device includes at least two luminescent devices, two current sensing elements, and two current regulators. The first and second luminescent device are driven by a rectified AC voltage for providing light according to first current and second current, respectively. The first current sensing element provides a first feedback voltage associated with the first current and the second current sensing element provides a second feedback voltage associated with the second current. The first current regulator provides a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein the waveform of the first regulating current setting follows the waveform of the rectified AC voltage. The second current controller is coupled in parallel to the second luminescent device and provides a constant second regulating current setting according to the second feedback voltage.

Abstract: A variable Vcom level generator circuit generates a variable Vcom voltage level. A variable Vcom voltage can be used for variable refresh rate display technology to prevent flicker on a display panel. The Vcom level can be changed based on the vertical frequency being used or can be changed based on external control signals.

Abstract: A voltage converter includes at least one charge pump voltage converter circuit. The voltage converter generates three voltages (e.g., 1.2 volts, 2.5 volts, and 1.8 volts) for an electronic system, which can be a smartphone or electronic tablet or other device. The charge pump voltage converter circuit provides an output voltage that is an average of its input voltages. Compared to a low dropout regulator, charge pump voltage converter circuit has high efficiency. This voltage converter will save power compared to converters using a low dropout regulator. An implementation of the voltage converter can includes at least two charge pump voltage converter circuits to generate to different output voltages.

Abstract: A voltage converter includes at least one charge pump voltage converter circuit. The voltage converter generates three voltages (e.g., 1.2 volts, 2.5 volts, and 1.8 volts) for an electronic system, which can be a smartphone or electronic tablet or other device. The charge pump voltage converter circuit provides an output voltage that is an average of its input voltages. Compared to a low dropout regulator, charge pump voltage converter circuit has high efficiency. This voltage converter will save power compared to converters using a low dropout regulator. An implementation of the voltage converter can includes at least two charge pump voltage converter circuits to generate to different output voltages.

Abstract: An LED lighting device driven by a rectified AC voltage includes a luminescent device, a charge storage unit and a current controller. The charge storage unit is configured to turn on the luminescent device when the rectified AC voltage is still insufficient to turn on the luminescent device. The current control unit is configured to allow the LED lighting device to have constant luminance regardless of the level of the rectified AC voltage or dimmer condition, thereby improving flicker phenomenon.

Abstract: An adaptive Vcom level generator circuit generates a variable Vcom voltage level. A variable Vcom voltage can be used for variable refresh rate display technology to prevent flicker on a display panel. The Vcom level can be changed based on the vertical frequency being used or can be changed based on external control signals.

Abstract: A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.

Abstract: One or more resistors or resistances are integrated in a 7-bit DVR or PVCOM integrated circuit. A 7-bit DVR or PVCOM integrated circuit includes a 7-bit DAC. The integrated resistors or resistances (R1, R2, or RSET, or any combination) reduces the number of external components, reduces the number of pins, and increases the accuracy of the DVR or PVCOM circuit. The least significant bit (LSB) of the DAC depends only on ratios of internal resistors, which can be made very accurate and independent of temperature.

Abstract: A voltage converter includes at least one charge pump voltage converter circuit. The voltage converter generates three voltages (e.g., 1.2 volts, 2.5 volts, and 1.8 volts) for an electronic system, which can be a smartphone or electronic tablet or other device. The charge pump voltage converter circuit provides an output voltage that is an average of its input voltages. Compared to a low dropout regulator, charge pump voltage converter circuit has high efficiency. This voltage converter will save power compared to converters using a low dropout regulator. An implementation of the voltage converter can includes at least two charge pump voltage converter circuits to generate to different output voltages.

Abstract: A VCOM generator circuit generates a VCOM signal for an electronic display. The VCOM circuit includes an operational amplifier having reduced supply rails. In an implementation, the VCOM circuit has at least three supply rails, AVDD, ground or GND, and VP or VN, or both. VP is less than AVDD and greater than VN. VN is higher than ground and below VP. The VCOM circuit with reduced voltage supply rails for VP and VN reduces power consumption of the VCOM op amps. By reducing power consumption, this also reduces the surface temperature of the integrated circuit.

Abstract: An LED lighting device driven by a rectified AC voltage includes a luminescent device, a charge storage unit and a current controller. The charge storage unit is configured to turn on the luminescent device when the rectified AC voltage is still insufficient to turn on the luminescent device. The current control unit is configured to allow the LED lighting device to have constant luminance regardless of the level of the rectified AC voltage, thereby improving flicker phenomenon.

Abstract: One or more resistors or resistances are integrated in a 7-bit DVR or PVCOM integrated circuit. A 7-bit DVR or PVCOM integrated circuit includes a 7-bit DAC. The integrated resistors or resistances (R1, R2, or RSET, or any combination) reduces the number of external components, reduces the number of pins, and increases the accuracy of the DVR or PVCOM circuit. The least significant bit (LSB) of the DAC depends only on ratios of internal resistors, which can be made very accurate and independent of temperature.