Abstract: A constant current LED driver comprising an LED driver to supply constant current to an LED circuit provided with a protection element, an open loop sensor to sense the open loop of the LED circuit and a clamping control to maintain the voltage in the LED circuit at a predetermined level. The open loop sensor may be a high voltage detector. The clamping control controls the power supplied to the LED circuit in response to the detection signals of the open loop sensor. In one embodiment, the clamping control controls the power supplied to the LED circuit according to the power of the detection signals.

Abstract: A transconductance stage is provided. The transconductance stage includes a tail current source, a differential pair, and two current mirrors. The input to each of the current mirrors is connected to the drain of a separate one of the transistors in the differential pair. The two current mirrors each have two outputs so that one of the outputs can be used to determine whether the output current exceeds a threshold (e.g. nine-tenths of the tail current). If the source current exceeds the threshold, extra source current is switched in to the output so that output source current is increased. Similarly, if the sink current exceeds the threshold, extra sink current is switched in to the output so that the output sink current is increased. This way, the transconductance stage can supply large output currents in response to a large signal input but maintains low quiescent current for small input signals.

Abstract: The present invention provides current regulation. The circuit includes a current regulation loop that includes a second control signal that is used to adjust the magnitude of the regulated current. The second control signal provides a signal that regulates the amount of current being supplied to a load. According to one embodiment of the invention, at least one current source is used to modulate the magnitude of the regulated current when a predetermined condition occurs. The predetermined condition may relate to temperature, current, voltage, and the like.

Abstract: The present invention is directed at providing methods in a circuit for smoothing transitions relating to a signal processing function. A reference signal is produced that relates to a DAC output code. The reference signal is used as a starting point, and is compared to the input signal. A feedback signal is produced that is used to adjust the reference. The invention can be used to implement signal processing functions such as peak detection, noise filtering, peak suppression, and the like, in which the transitions in the signal are smoothed. The invention can implement these functions with a minimal complexity and a minimal die area.

Abstract: The invention is directed towards a charging circuit for charging a cell that may be deeply discharged. A primary charging circuit charges the cell when the cell is not deeply discharged. A deeply discharged charging circuit charges the cell when the cell is deeply discharged. Determining when the cell is deeply discharged includes determining when the voltage of the cell is above, below, or equal to a predetermined threshold. According to one embodiment of the invention, the predetermined threshold is 2V. When the cell voltage is below a predetermined threshold voltage, which according to one embodiment is 0.5V, a low-voltage charging path is used to charge the cell.

Abstract: The present invention provides a redundant break before make digital circuit. Redundant circuits are used to provide a path to ground for a charging signal when a fault condition exists. The fault condition may be based on characteristics relating to the signal or the chip itself. For example, a fault condition may occur when a temperature measured on the chip exceeds a predetermined threshold. A fault condition may also occur when the signal is above or below a predetermined threshold. For example, a fault condition may occur when the current of the signal is above a predetermined level. The fault conditions are monitored and the state of a switch that couples the cell to the charging path is monitored. When the switch is open and a fault condition has occurred, there are redundant paths to ensure that a switch closes to provide the path to ground during the fault condition.

Abstract: A bias current source circuit with high power supply rejection. In one embodiment, the present invention is comprised of a bias current source circuit. The bias current source circuit is comprised of a primary current source coupled to a power supply, a secondary current source for biasing the primary current source and also coupled to the power supply, and a gain stage. In the present embodiment, the primary current source includes a first transistor having a first region coupled to a second resistor and a second transistor having a first region coupled to the second resistor. In the present embodiment, the gain stage includes a first input coupled to the second region of the first transistor. The simple gain stage further includes a second input coupled to the second region of the second transistor. The gain stage also includes an output coupled to the first regions of the first and second transistors.

Abstract: A bandgap-based reference voltage generator circuit with an increased output reference voltage and a reduced temperature coefficient uses a curvature correction bias voltage to significantly reduce the degree of variation of the bandgap-based reference voltage over temperature. A current having a negative temperature coefficient is conducted by a resistor having a positive temperature coefficient. The resultant voltage across the resistor has an arcuate voltage-versus-temperature characteristic with a direction of incurvature that is substantially opposite the direction of incurvature of the corresponding arcuate voltage-versus-temperature characteristic of the voltage generated by a conventional bandgap reference voltage generator circuit. These voltages are summed together to produce a bandgap-based reference voltage which is greater in magnitude than a conventional bandgap reference voltage and has a significantly reduced temperature coefficient.

Abstract: A precision voltage reference circuit for generating a constant reference voltage over a range of operating temperatures uses a bandgap voltage generator which is compensated with replicated currents fed back from the bandgap stage as control currents. These currents are attenuated and fed back in proper proportions to correct for bias conditions which would otherwise vary with temperature.