摘要:
A delta-sigma analog-to-digital converter (ADC) circuit improves performance by reducing the amount of noise and other error sampled by the reference switching circuit. The reference switching network is operated intermittently only when the charge on an input integrator exceeds a threshold, thereby preventing the input integrator from saturating, while avoiding needlessly injecting reference noise. The input to the ADC may be a current injected directly into a summing node of the integrator, or may be a voltage supplied through another switching network.
摘要:
A delta-sigma analog-to-digital converter (ADC) circuit improves performance by reducing the amount of noise and other error sampled by the reference switching circuit. The reference switching network is operated intermittently only when the charge on an input integrator exceeds a threshold, thereby preventing the input integrator from saturating, while avoiding needlessly injecting reference noise. The input to the ADC may be a current injected directly into a summing node of the integrator, or may be a voltage supplied through another switching network.
摘要:
An electronic system generates at least one floating supply voltage, wherein during operation of the circuit the floating supply voltage tracks a common mode voltage of first and second differential input signals. By tracking the common mode voltage, in at least one embodiment, the floating supply voltage adjusts as the common mode voltage changes. Thus, the floating supply voltages can be based upon the peak-to-peak values of the first and second output signals without factoring in the common mode voltage. In at least one embodiment, the electronic system provides the floating supply voltages to an amplifier. The amplifier amplifies the first and second differential input signals and generates differential output signals. A differential sampling circuit samples the differential output signals to cancel the common mode voltage from the differential output signals. In at least one embodiment, an analog-to-digital converter converts the sampled differential output signals into a digital output signal.
摘要:
An electronic system generates at least one floating supply voltage, wherein during operation of the circuit the floating supply voltage tracks a common mode voltage of first and second differential input signals. By tracking the common mode voltage, in at least one embodiment, the floating supply voltage adjusts as the common mode voltage changes. Thus, the floating supply voltages can be based upon the peak-to-peak values of the first and second output signals without factoring in the common mode voltage. In at least one embodiment, the electronic system provides the floating supply voltages to an amplifier. The amplifier amplifies the first and second differential input signals and generates differential output signals. A differential sampling circuit samples the differential output signals to cancel the common mode voltage from the differential output signals. In at least one embodiment, an analog-to-digital converter converts the sampled differential output signals into a digital output signal.
摘要:
An offset correction circuit removes DC offset from an analog audio output signal by comparing transitions of digital audio values to which the analog output signal is related to the output of a monitor that monitors the analog output signal. The monitor may be a zero-crossing detector and the transitions of the digital signal that are compared may be transitions of the most-significant bit (MSB) of the digital audio values. A filtering algorithm or filter circuit may be used to average a result of the comparison of the transitions, so that the offset is slowly and accurately removed. A chopped or autozero comparator may be used to further reduce error in the offset determination.
摘要:
An electronic system includes two power supplies to supply an operating voltage to a switching power converter. The first power supply, referred to as a start-up power supply, includes a first source follower transistor to conduct a start-up current for a controller and supply an operating voltage for the controller. The controller controls operation of the switching power converter. A second power supply, referred to as an auxiliary power supply, includes a second source follower transistor to conduct a steady-state operational current for the controller and supply an operating voltage for the controller. In at least one embodiment, once the second power supply begins supplying the operating voltage to the controller, the start-up power supply automatically ceases supplying the start-up current to the controller.
摘要:
An electronic lighting system and method described herein control energy provided to an electronic lighting device, such as one or more light-emitting diodes (LEDs) and/or compact fluorescent lamps (CFLs), of the electronic lighting system. A triac-based dimmer phase cuts a line voltage provided to the electronic lighting system. A controller of the electronic lighting system utilizes a probing system to overcome idiosyncrasies of the triac-based dimmer to allow the controller to probe and sense the line voltage. To reduce energy consumption, rather than probing each cycle of the output voltage of the triac-based dimmer, the controller periodically or intermittently probes the output voltage of the triac-based dimmer.
摘要:
An LED lighting device includes an auxiliary power supply that supplies power to a control circuit of the LED lighting device that receives an input from a terminal of a light-emitting diode (LED) string of the lighting device that has a substantially lower voltage than the line voltage to which the lighting device is connected. The terminal may be within the LED string, or may be an end of the string. A linear regulator may be operated from the voltage drop across a number of the LEDs in the string so that the energy wasted by the auxiliary power supply is minimized. In other designs, the auxiliary power supply may be intermittently connected in series with the LED string only when needed. The intermittent connection can be used to forward bias a portion of the LED string when the voltage supplied to the LED string is low, increasing overall brightness.
摘要:
A light emitting diode (LED) lighting system includes a switching power converter having an input for coupling to an alternating current (AC) power source, an output, and a switch. The LED lighting system also includes an LED lighting subsystem coupled to receive power from the output of the switching power converter. The LED lighting subsystem includes a current source for one or more LEDs, and the current source has a control node and a sense node. The LED lighting system additionally includes a switch state controller coupled to the switching power converter and coupled to the LED lighting subsystem. The switch state controller controls switching of the switch and varies a control current provided to the control node of the current source based on at least a parameter sensed from the sense node.
摘要:
A system and method includes a controller that alternately enables at least two different current paths for a current flowing through a dimmer when the dimmer is in an OFF mode. In at least one embodiment, enabling and disabling the current paths allows a power supply of the dimmer to continue functioning and provides the controller sufficient voltage to continue functioning. One of the current paths is a low impedance path and another current path is a path to a voltage supply node of a switching power converter controller. In at least one embodiment, the controller generates an impedance control signal to enable a low impedance current path for a current in the dimmer and alternately provide a current path to the voltage supply node for the controller.