Linear Technology Corporation

Analog Devices International Unlimited Company

Analog Devices,inc.

Linear Technology Holding LLC

Eric Stephen Young

Xin Qi

Bryan Avery Legates

Bin Zhang

Keith Szolusha

Qiuzhong Wu

Keith D Szolusha

Chad Cosby

Mark William Marosek

This disclosure describes techniques for extending a range of bidirectional bus communications through the use of a differential signal path. The disclosed techniques include first separating the bidirectional bus into first and second unidirectional buses that transmit and receive signals, respectively, and then communicating the signals from the first and second unidirectional buses over a differential signal path. The separation of the bidirectional bus into the first and second unidirectional buses is performed using logic circuitry that blocks or permits communication between a given one of the first and second buses and the bidirectional bus based on whichever one of the first and second buses becomes dominant first. If the logic circuitry determines that the first bus becomes dominant before the second bus, the logic circuitry permits communications between the first bus and the bidirectional bus and blocks communications between the second bus and the bidirectional bus.

Bidirectional signal separation

An electronic circuit comprises an analog-to-digital converter (ADC) circuit. The ADC circuit includes a pre-amplifying transistor and a quantizer circuit. The pre-amplifying transistor includes a base, an emitter and a collector. The pre-amplifying transistor is configured to receive an input voltage at the base that varies logarithmically; and produce an output voltage at the collector according to a comparison of a reference voltage and a difference between the input voltage and a voltage at the emitter. The quantizer circuit is operatively coupled to the pre-amplifying transistor and is configured to generate a digital value for the input voltage using the output voltage produced by the pre-amplifying transistor.

Logarithmic scale analog to digital converter for wide dynamic range avalanche photodiode current companding

In some boost converter applications, an input voltage normally exceeds a regulated output voltage. The operation of the boost converter in this condition can be referred to as a pass-through operation. Using various techniques, the efficiency of a pass-through operation of a synchronous boost regulator circuit can be greatly improved. For example, a synchronous boost regulator circuit can include an input voltage Vto output voltage Vvoltage comparator that can accurately monitor the output voltage to detect the pass-through operation. In a pass-through operation, the high-side switch can be kept ON to maintain high efficiency, and the quiescent current of the regulator circuit can be minimized by setting portions of the control circuit into a sleep mode.

Synchronous boost regulator circuit with pass-through operation control

Techniques for an integrated slew-rate control circuit are provided. In certain examples, an adjustable, integrated slew-rate control circuit for a bypass transistor can provide three decades of adjustability. In an example, a slew-rate control circuit can include a load bypass transistor, a slew-rate control capacitor, electrically coupled between a conduction node of the load bypass transistor and a control node of the load bypass transistor, and a current mirror circuit. The current mirror circuit can include a sense transistor electrically coupled in series with the slew-rate control capacitor and the control node, and a mirror transistor electrically coupled between a power supply and the control node, to selectively provide, to or from the control node, a shunt current that bypasses the slew-rate control capacitor to limit a slew rate of a voltage at the conduction node.

Load bypass slew control techniques

A technique to eliminate perceptible flickering by LEDs being dimmed by PWM pulses is disclosed. A controllable oscillator controls a switching frequency of a converter for supplying a regulated current or regulated voltage. The converter controls a first switch at a switching frequency. A varying second signal level is generated by a spread spectrum control (SSC) circuit for controlling the oscillator to vary the switching frequency during operation. A PWM dimming circuit generates a string of PWM pulses that control a switch in series with the LEDs. The SSC circuit is synchronized with the PWM pulses to generate the same second signal level at a start of each PWM pulse, such that the switching frequency of the converter is forced to be substantially the same at the start of each PWM pulse while the pulse widths are constant. The repeating driving current waveform eliminates perceptible flicker by the LEDs.

PWM control for LEDs with reduced flicker when using spread spectrum switching frequencies

Protection circuitry protects a boost converter coupled between input and output nodes for driving a load coupled to the output node. The protection circuitry may comprise a first circuit configured for monitoring a voltage at the output node, the voltage being caused by a signal having a voltage proximate to, or lower than, an input voltage of the boost converter. The protection circuitry may also include a second circuit configured for coupling together the input node with respect to the output node and enabling the boost converter only if the monitored voltage exceeds a reference voltage.

Circuitry and methodology for protecting a boost DC/DC converter

A circuit for controlling pulsed current to a load, one application of which is in LED dimmer circuitry, comprises first and second reference nodes for receiving a supply voltage, an input node for receiving a timing signal such as a PWM signal, and a controlled switch coupled between the first and second reference voltage nodes for supplying current to the load. Pull-up circuitry may be coupled between a control electrode of the controlled switch and first reference voltage node, and a pull-down switch coupled between the control electrode and second reference voltage node. A control circuit coupled between the input node and control electrode of the controlled switch is configured to control the controlled switch in response to the timing signal. The circuit may further include a reference voltage source configured for producing a voltage of magnitude independent of supply voltage magnitude. The control circuit is coupled to the reference voltage source and operative to control the controlled switch in response to the timing signal and reference voltage.

Circuit and methodology for supplying pulsed current to a load, such as a light emitting diode

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. Current flow is directed by the switch, when in a closed state, to the second circuit point to bypass the load. A regulator circuit has an output coupled to a control input of the switch. The regulator circuit has a first input for receiving a sensed load parameter, a second input for receiving a sensed current level signal at the second circuit point when the switch is in its closed state, and a third input for receiving a sensed current level signal at the second circuit point, measured directly, when the switch is in an open state. A fixed minimum time is set for the switch to be in the open state. The third input inhibits re-closing of the switch, providing current limit protection for the switch.

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Apex, NC, United States of America

Eric Stephen Young