Bidirectional power conversion with multiple control loops
Granted: May 26, 2009
Patent Number:
7538532
Bidirectional power conversion systems provide the ability to change power attributes to and from a component. Current bidirectional power conversion systems use a unidirectional power converter for each direction. The integration of the two normally independent power converters results in a bidirectional power converter with nearly half the size, weight, volume, cost and complexity. Described are embodiments of bidirectional power conversion systems that allow power transfer between two…
Constant power foldback mechanism programmable to approximate safe operating area of pass device for providing connection to load
Granted: May 26, 2009
Patent Number:
7538528
System and methodology for supplying power to a load using a pass device for connecting the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit modifies the current threshold in accordance with a prescribed condition. The foldback circuit is configured to vary the current threshold in accordance with an approximate safe operating area of the pass device.
Method to control the output common mode in a differential OPAMP with rail-to-rail input stage
Granted: May 12, 2009
Patent Number:
7532072
A differential amplifier with a rail-to-rail input stage includes a feedback circuit that maintains the output common mode voltage of the amplifier within a narrow range of an externally supplied value. To reduce harmonic distortions and to further stabilize the output common mode voltage of the amplifier, current is controllably drawn from a biasing circuit coupled to an intermediate stage of the amplifier. Optionally, to reduce harmonic distortions and to further stabilize the output…
Gradient insensitive split-core digital to analog converter
Granted: May 12, 2009
Patent Number:
7532140
Digital to analog converter circuits and methods are provided for producing an analog output voltage indicative of a digital input signal with at least partial insensitivity to error gradients. Described are split-core resistive elements, which include a plurality of one-dimensional or multi-dimensional resistive strings, that may be used to reduce or substantially eliminate the effects that error gradients have on the linearity of the analog output voltages of a resistive string or…
Switched converter with variable peak current and variable off-time control
Granted: May 5, 2009
Patent Number:
7528587
A converter coupled to a DC voltage input and connectable to a load, includes a signal responsive switch coupled between a first circuit point and a second circuit point. In lieu of burst mode operation during low load conditions, the peak switch current is varied directly with load condition and a switch deactivation interval is varied inversely with load condition. The switch deactivation level is within a maximum level to avoid audio frequency band interference, while maintaining high…
Switching regulator over voltage reduction circuit and method
Granted: April 14, 2009
Patent Number:
7518351
Output voltage overshoot of a switching regulator is controlled by deactivating switching operation when a signal proportional to the output voltage exceeds a variable threshold level, with the threshold level set as a function of regulator output current. In accordance with an embodiment, a difference signal is generated that corresponds to a difference between an output voltage feedback signal and a constant reference voltage. The generated difference signal is combined with a signal…
Dual FET output stage with controlled output DV/DT for reduced EMI and input supply noise
Granted: March 31, 2009
Patent Number:
7511390
The slew rate of switching circuits, e.g. for DC to DC converters, is controlled without unduly sacrificing total switching time, by providing a weaker switching transistor in parallel with each stronger main switching transistor. Switching of the weaker transistor is controlled so as to have a slower slew rate in transitions between switch states than transitions of the main transistor. The main transistor switches at a fast rate for efficiency, but the slower transition by the weaker…
System for providing power over communication cable having mechanism for determining resistance of communication cable
Granted: March 31, 2009
Patent Number:
7511515
Novel system and methodology for determining resistance of wires in a communication cable having at least two pairs of wires used for providing power from a power supply device to a powered device. A measuring mechanism may determine DC resistance of the wires before the power supply device applies power to the communication cable.
Classification mechanism in system for supplying power over communication link
Granted: March 17, 2009
Patent Number:
7504744
System and methodology for providing classification of a load in a power supply system for providing power over a communication link. The power supply system has a classification engine for probing the load to determine a characteristic of the load. The classification engine supplies the load with multiple classification signals to determine multiple response signals presented by the load in response to the respective classification signals.
Asymmetric minor hysteresis loop model and circuit simulator including the same
Granted: March 10, 2009
Patent Number:
7502723
The present disclosure relates to simulating inductors wound on a ferromagnetic core as the magnetic material saturates. In one application, the present disclosure is advantageously used to model the asymmetric minor hysteresis loops commonly traversed by the output inductor of a switch mode power supply. An advantage of the subject matter of the disclosure is that it allows practical nonlinear inductors to be modeled in a computationally lightweight manner without conventional…
Circuit and method of detecting and resolving stuck I2C buses
Granted: January 13, 2009
Patent Number:
7478286
A integrated circuit (IC) implementation of a protection circuit detects and resolves a fault on a bus, such as a stuck-low condition on an I2C bus. The circuit includes logic that detects a fault condition caused by the slave device, e.g. when one or both lines are low for a period longer than a timeout value in the I2C example. Upon detecting the fault condition, the logic disconnects the slave device from the data line and the clock line, for example by activation of switches…
Light load regulator for isolated flyback converter
Granted: December 30, 2008
Patent Number:
7471522
A regulator may include a load voltage sensing circuit configured to generate a feedback signal representative of output voltage from an isolated flyback converter. The regulator may include a pulse generator configured to controllably generate the pulses and to increase at least one off time and at least one period of the pulses after a load on the flyback converter decreases.
Systems and methods for providing compact digitally controlled trim of multi-segment circuits
Granted: December 23, 2008
Patent Number:
7468686
A trimdac circuit for adjusting the output of a digital-to-analog converter (DAC) is provided. The trimdac may be used to adjust a plurality of resistor segments in the DAC. The trimdac may include a programmable Read Only Memory (ROM) or other suitable memory device. The ROM may include a plurality of multi-bit digital words. Each of the multi-bit digital words may control a plurality, and most preferably a pair of variable resistance circuits. Each of the pair of variable resistance…
Reducing oscillations in system with foldback current limit when inductive load is connected
Granted: December 16, 2008
Patent Number:
7466039
System and methodology for driving an inductive load using a pass device for providing hot swap connection to the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit controls the current limit circuit to reduce the current threshold when a voltage across the pass device is above a prescribed value. A filter circuit is coupled to the foldback circuit for reducing oscillations when the inductive load is connected to the…
Variable frequency current-mode control for switched step up-step down regulators
Granted: December 16, 2008
Patent Number:
7466112
A switched regulator circuit provides step-up and step-down operation in which the level of the input voltage can be greater, equal to, or less than a preset controlled output voltage. A four switch arrangement or two switch arrangement provides buck, boost, and buck-boost regulation under variable frequency valley-peak current mode control. A single sense resistor may be utilized for sensing inductor current during each duty cycle.
Regulator for isolated flyback power supply using primary side sensing
Granted: December 9, 2008
Patent Number:
7463497
A regulator for an isolated flyback power supply using primary side sensing. The regulator may include an error circuit configured to generate an error signal representative of the difference between a target value and a measured value, a sample and hold circuit, and a controller circuit. The controller circuit may be configured to cause the sample and hold circuit to sample the value of a derived signal that is derived from a connection to the primary winding at a time when the primary…
Folded cascode amplifier having improved slew performance
Granted: October 28, 2008
Patent Number:
7443237
A folded cascode amplifier having improved slew comprises an input differential transistor pair circuit, a cascode branch circuit coupled to the differential pair circuit, and a boost circuit for increasing branch current when the amplifier is in a slew condition. The additional current increases slew of the amplifier without negatively affecting amplifier characteristics.
Adaptive power control for hysteretic regulators
Granted: October 7, 2008
Patent Number:
7432695
A hysteretic regulator may be set to an active mode when voltage at an output falls to a first threshold level. In the active mode, charge is applied to an output node by a current having a set limit value. The regulator is set to an inactive mode when the voltage at the output node rises to a second threshold level. The current limit value is automatically adjusted as a function of average regulator current. An indication of average regulator current may be obtained by charging a sense…
Combination of high-side and low-side current sensing in system for providing power over communication link
Granted: September 16, 2008
Patent Number:
7426374
A system for supplying power to a load over a communication link has high-side current sensing circuitry for measuring a high-side current value, low-side current sensing circuitry for measuring a low-side current value, and control circuitry responsive to both the high-side current value and the low-side current value to detect a fault condition, detect information from the load, and/or transmit information to the load by creating a prescribed unbalance between the high-side current and…
Bandgap curvature correction and post-package trim implemented therewith
Granted: September 2, 2008
Patent Number:
7420359
A bandgap voltage reference circuit having temperature curvature correction, comprises a bandgap voltage source configured to generate an output voltage, and a novel curvature correction circuit. The correction circuit is responsive to the bandgap voltage source output voltage and connected to apply a curvature correction signal to the bandgap voltage source to compensate for output voltage temperature dependency of the bandgap voltage source.
