Analog Devices,inc.

Semiconductor Components Industries, LLC

Analog Devices International Unlimited Company

Jonathan Kraft

Kenneth G Richardson

David Aherne

Eric A Sagen

A package with a laminate substrate is disclosed. The laminate substrate includes a first layer with a first terminal and a second terminal. The laminate substrate also includes a second layer with a conductive element. The laminate substrate further includes a first via and a second via that electrically connect the first terminal to the conductive element and the second terminal to the conductive element, respectively. The package can include a die mounted on and electrically connected to the laminate substrate.

Package with electrical pathway

A drive system for multiple LED strings powered by a common line voltage. Current control circuits are connected in series with respective LED strings; each current control circuit includes a drive transistor (typically a FET) which causes a desired LED string current to be conducted. In one embodiment, the current conducted by a selected one of the LED strings is controlled by the line voltage regulation loop, while the currents conducted by the remaining LED strings are controlled by respective local current loops, thus avoiding conflicts between the local current and line voltage regulation loops. The LED string to be current regulated by the line voltage regulation loop can be determined by a variety of criteria, such as the current control circuit having the maximum FET gate voltage, the minimum FET source voltage, the minimum FET drain voltage, the maximum FET gate-source voltage, or the minimum FET drain-source voltage.

Multi-string LED drive system

A LED drive system for controlling an off-chip power supply enables the power supply function to be located 'off-chip'&#x2014;i.e., on an IC which is separate from the IC containing the other LED drive system components. The off-chip supply provides a common line voltage for LED strings connected in series with respective current sink circuits at respective junctions, in response to a signal applied to a control input. The system includes a 'minimum' circuit which outputs the least of the voltages at the junctions, and an I/O pin which receives a signal that varies with the output of the minimum circuit. When the external supply's control input is coupled to the system's I/O pin, the present system controls the output of the external power supply as needed to provide a desired common line voltage.

LED drive system for controlling an off-chip power supply

A LED current control system for use with an LED drive system which includes LED strings connected in series with respective current sink circuits, each of which causes a current to be conducted by the LED string to which it is connected. The drive system includes 3 or more 'dimming' inputs with which the LED string currents can be adjusted. The LED current control system comprises at least one minimum circuit which receives two or more dimming inputs and produces an output which is proportional to the lesser of the inputs, a multiplier circuit which receives the outputs of the minimum circuits and at least one other dimming input and produces an output ILED which is proportional to the product of the received signals, and a sink control circuit which receives ILED and controls the current sink circuits such that the string currents vary with ILED.

LED current control system for LED drive system with multiple dimming inputs

A multi-string LED drive system for multiple LED strings powered by a common line voltage. A plurality of current control circuits are connected in series with respective LED strings, each of which includes a transistor which causes a desired LED string current to be conducted when a sufficient voltage is applied to the transistor's gate. A 'maximum' circuit receives each of the gate voltages at respective inputs and outputs a voltage which is proportional to the greatest of the received voltages. A line regulator circuit receives the output of the maximum circuit and a signal which represents a target gate voltage at respective inputs and generates the common line voltage such that the highest of the gate voltages is approximately equal to the target gate voltage, such that system power efficiency is optimized in cases of imbalance between LED string voltage drops and/or sink device characteristics.

A line voltage control circuit for use with a multi-string LED drive system which provides a common line voltage for multiple LED strings that are connected to respective current sink circuits at respective junctions. An error amplifier receives the minimum junction voltage and a reference 'desired junction voltage' at respective inputs, and a voltage regulator outputs the line voltage in response to a voltage applied to a feedback input. A comparator toggles an output when the maximum junction voltage (V) exceeds a reference limit (V). A multiplexer receives the error amplifier output and a fixed voltage at respective inputs and provides one of the signals to the regulator's feedback input in response to the comparator output. When V&#x3e;V, the fixed voltage is provided to the feedback input and the line voltage is reduced, thereby protecting low voltage current sinks from potentially damaging high voltages.

Line voltage control circuit for a multi-string LED drive system

In one embodiment, a PWM controller is configured to inhibit a drive signal responsively to a bulk input voltage remaining at a low value for a time interval.

Method of forming PWM controller

A current source driving an LED is monitored for a fault condition such as an open circuit or a short circuit. The current source may be disabled and/or a common power source may be disabled in response to the type of fault condition. A test current may be applied to the current source to determine the type of fault.

Fault detection and handling for current sources

In one embodiment, a PWM controller includes a circuit operably coupled to inhibit a drive signal responsively to a bulk input voltage remaining at a low value for a time interval and to re-enable the drive signal subsequently to the time interval responsively to the bulk input voltage increasing to greater than the first value subsequently to the time interval. In another embodiment, a method of forming a PWM controller includes configuring the PWM controller to use a clock signal to form a drive signal and to sense a bulk input voltage decreasing to no greater than a first value and to disable the drive signal without disabling the clock signal responsively to the bulk input voltage remaining no greater than the first value for a time interval.

PWM controller having drive control with input voltage sensing and method therefor

In one embodiment, a PWM controller is configured to inhibit forming a drive signal responsively to an overload sense signal having a value that is no greater than a first value for a first time interval and to form a first duration of the first time interval responsively to the overload sense signal.

Growing community of inventors

Frederick, CO, United States of America

Jonathan Kraft