Abstract: A maximum voltage selection circuit may include multiple inputs, each for receiving a different input voltage, an output for delivering the highest of the input voltages, and a voltage selection circuit. The voltage selection circuit may automatically select the input having the largest voltage magnitude, automatically deliver the voltage at the selected input to the output, and not draw quiescent operating current from any of the inputs.

Abstract: Circuitry for detecting faults in a system for supplying power from an input node to an output node and having at least one switch coupled between the input node and the output node. The fault detecting circuitry is configured for indicating a fault condition of the switch when the switch is commanded to turn on and at least one of the following conditions is detected: a voltage across the switch exceeds a predetermined value or a value of the switch control signal is insufficient to turn the switch on. The fault condition is indicated only if the detected condition is present for a predetermined period of time.

Abstract: A ripple monitoring circuit may generate information indicative of a failing component in a power supply. At least one input may receive a ripple signal from the power supply that has a ripple component. A quantization circuit may repeatedly quantize the amplitude of the ripple component. A ripple amplitude statistics counter bank may count and store the number of times that different quantized amplitudes or different ranges of quantized amplitudes of the ripple component occurred. A ripple monitoring circuit may generate information about a power supply. At least one input may receive a ripple signal from the power supply that has a ripple component. A ripple measurement circuit may measure a characteristic of the ripple component. A storage circuit may store information about the measurement. A comparison circuit may compare information stored in the storage circuit with a threshold value and indicate when the stored information meets or exceeds this threshold value.

Abstract: A device is configured to control a transition timing of a switching DC/DC converter for providing power to a load device. The load device has a first operational phase that is sensitive to external noise and a second operational phase that is immune to the external noise. The device includes an input terminal coupled to an external device to receive a start signal of the first operational phase for the load device. The device also includes control circuitry configured to, responsive to the start signal, control a transition frequency of the DC/DC converter to avoid transitioning an output of the switching DC/DC converter during the first operational phase.

Abstract: A PSE includes a PSE controller that performs a handshaking routine with any PDs connected to the data wire pairs and spare wire pairs and applies power to the data wire pairs and spare wire pairs, via a switch, if certain conditions are met. Two different levels of currents are supplied to different terminals of the PSE controller that are connected to the data wire pairs and the spare wire pairs, and the resulting voltages are measured. The voltages are used to determine the PD impedances at the ends of the data wire pairs and spare wire pairs to determine whether a PD is connected to the data wire pair, whether another PD is connected to the spare wire pair, or whether a single PD is connected to both the data wire pairs and the spare wire pairs.

Abstract: Technique for providing power to a powered device (PD) over a cable having first and second sets of twisted pairs, such as signal pairs and spare pairs. Power Sourcing Equipment (PSE) circuitry is coupled via a first switch to the second set, e.g. to the spare pairs. A switch control circuit turns the first switch off to enable the PSE circuitry to perform a prescribed operation in connection with the PD over only the first set, e.g. over the signal pairs, and turns the first switch on to enable the PSE circuitry to perform the prescribed operation in connection with the PD over the first and second sets.

Abstract: A precision temperature sensing system includes a heater and a sensing element disposed on a semiconductor substrate. A power source drives the heater on a periodic basis according to a received clock signal. The sensing element senses the heat emitted by the heater and diffused through the semiconductor substrate. Processing circuitry coupled to the sensing element adjusts a phase of the periodic heater driving signal based on the heat sensed by the sensing element. The processing circuitry determines a temperature based on a thermal diffusivity (TD) of the semiconductor substrate, the adjusted value of the phase, and a known distance between the heater and the sensing element. A second temperature sensor can be disposed on the same substrate as the precision temperature sensing system, and calibrated based on temperature measurements obtained while applying a reference frequency signal to the precision sensing system.

Abstract: A method and system of compensating for distortion in a baseband in-phase (I) and a corresponding baseband quadrature (Q) signal. The circuit includes an in-phase I attenuator configured to attenuate the baseband in-phase I signal and an in-phase Q attenuator configured to attenuate the baseband Q signal. There are one or more circuits that are configured to receive the attenuated in-phase I signal and the attenuated baseband Q signal. Each circuit performs a different calculation based on predetermined equations configured to determine the IM2, HD2@0°, HD2@90°, IM3@0°, IM3@90°, HD3@0°, and HD3@90°. The distortion compensation circuit is configured to use the result of at least one of the calculation circuits to generate I and Q distortion compensation signals.

Abstract: A method and system of driving an LED load. There is a power stage that is configured to deliver a level of current indicated by a control signal to the LED load when a PWM signal is ON and stop delivering the level of current when the PWM signal is OFF. There is a feedback circuit that is configured to generate the operating point signal, which causes the power stage to deliver a level of current indicated by the control signal, when the PWM signal is ON. A store and hold circuit is configured to store an information indicative of a level of the operating point signal just after the PWM signal is turned OFF and cause the operating point signal to be at that level just before the PWM signal is turned ON.

Abstract: An RMS-DC converter includes a chopper-stabilized square cell that eliminates offset, thus enabling high-bandwidth operation. The chopper-stabilized offset requires only a small portion of the circuitry (i.e., a single component square cell) which operates at high frequencies, and is amenable to using high-bandwidth component square cells. Using the chopping technique minimizes required device sizes without compromising an acceptable square cell dynamic range, thereby maximizing the square cell bandwidth. The RMS-DC converter consumes less power than conventional RMS-to-DC converters that requires a high-frequency variable gain amplifier.

Abstract: A circuit for protecting a semiconductor element is provided in a system for supplying power from an input node to an output node. The circuit has an analog multiplier responsive to a voltage across the semiconductor element and a current flowing through the semiconductor element to produce an output voltage. A transconductance amplifier is coupled to an output of the analog multiplier for receiving the output voltage of the analog multiplier to produce an output current. An analog RC circuit coupled to the output of the transconductance amplifier is configurable to include a selected number of resistive elements having selected resistance values and a selected number of capacitive elements having selected capacitance values. The configuration of the RC circuit is carried out to provide an RC thermal model that reproduces a desired thermal behavior of the semiconductor element.

Abstract: A circuit for protecting a semiconductor element is provided in a system for supplying power from an input node to an output node. The circuit has an analog multiplier responsive to a voltage across the semiconductor element and a current flowing through the semiconductor element to produce an output voltage. A transconductance amplifier is coupled to an output of the analog multiplier for receiving the output voltage of the analog multiplier to produce an output current. An analog RC circuit coupled to the output of the transconductance amplifier is configurable to include a selected number of resistive elements having selected resistance values and a selected number of capacitive elements having selected capacitance values. The configuration of the RC circuit is carried out to provide an RC thermal model that reproduces a desired thermal behavior of the semiconductor element.

Abstract: In a method performed by a PoE system, a PSE is able to detect whether a PD is compatible for receiving power via four wire pairs in the standard Ethernet cable. The PSE provides a current limited voltage to a first and second pair of wires in the cable, during a detection phase, to detect a characteristic impedance of the PD. In the PSE, a first resistor is connected to a third wire pair and a second resistor is connected to a fourth wire pair. During the detection phase, the PSE detects the relative currents through the resistors. If the currents are the same, then the PSE knows the PD is able to receive power via the four wire pairs. The PSE then applies the full PoE voltage to the first and second wire pairs and connects the third and fourth wire pairs to a low voltage via a MOSFET.

Abstract: A driver circuit for a PNP power transistor in an LDO regulator uses a Class AB (push-pull) buffer to supply the necessary base current to an NPN driver transistor, where the NPN driver transistor has its collector connected to the base of the PNP power transistor. A front end circuit of the driver, coupled to drive the Class AB buffer, uses a current diverting transistor, where a first portion of the current is used to control the pull-up transistor in the Class AB buffer, and the remainder of the current is used to control the pull-down transistor in the Class AB buffer, so the driver is very efficient. The portion of the driver circuit between the input of the driver circuit and the base of the NPN driver transistor is an inverting circuit. The driver can properly operate with an input voltage within two diode drops of ground.

Abstract: A power supply system includes a power source; a load device configured to receive power from the power source; and a power interface device coupled to the power source and the load device and configured to change a first voltage provided by the power source to a second voltage for operating the load device. The power interface device include a main switching converter configured to operate at a first switching frequency and source low frequency current to the load device and an auxiliary switching converter coupled in parallel with the main switching converter and configured to operate at a second and different switching frequency and source fast transient high frequency current to the load device.

Abstract: A method and a circuit dynamically adjust a frequency of a clock signal that drives the operations of a power converter. The method includes (a) detecting a change from a predetermined value in an output voltage of the power converter; and (b) upon detecting the change, changing the frequency of the clock signal so as to restore the output voltage. The change, such as a load step-up, may be detected by comparing a feedback signal generated from the output voltage and a predetermined threshold voltage. In one implementation, changing the switching frequency is achieved in increasing (e.g., doubling) the frequency of the clock signal, as needed. The frequency of the clock signal need only be changed for a predetermined time period.

Abstract: A frequency converting element includes a mixer and a charge pump. The mixer has first and second input nodes and an output node, and an input code of the charge pump is coupled to the output node of the mixer. The charge pump receives a mixer output signal at the input node of the charge pump, and outputs an amplified version of the mixer output signal.

Abstract: A method and system of driving an LED load. A driver is configured to deliver a level of current indicated by a control signal to the LED load when a PWM signal is ON and stop delivering the level of current when the PWM signal is OFF. An output capacitance element is coupled across a differential output of the LED driver. A feedback path, having a store circuit, is configured to store an information indicative of a first voltage level across the output capacitance element as a stored feedback reference signal just after the PWM signal is turned OFF. The feedback path causes the voltage across the output capacitance element to be at the first voltage level just before the PWM signal is turned ON.

Abstract: A circuit may increase input transconductance. An input stage may include a field effect transistor (FET) that has a gate, source, drain, and body terminal. An amplifier may generate an amplified version of the input voltage received that is applied to the body terminal of the FET. Application of the amplified version to the body terminal of the FET may increase the transconductance of the FET compared to what it would be in the same circuit without the amplified version being applied to the body terminal of the FET.

Abstract: Switching regulator methods and systems for supplying output current at a regulated voltage level to a load. The regulator has a primary side that is galvanically isolated from a secondary side. The regulator includes a transformer having a primary winding on the primary side and a secondary winding on the secondary side, coupled to a load. A switch, coupled to the primary winding, controls current flow through the primary winding. A first feedback control loop, responsive only to primary side signal values, regulates a constant average voltage at the output node. An optional second feedback control loop, responsive only to primary side signal values, reduces voltage ringing at the output node.