Texas Instruments Corporation

National Semiconductor Corporation

Texas Instruments Incorporated Deutschland, Gmbh

Joseph V DeNicholas

Daniel Ross Herrington

James Harbison Masson

Christoph Goeltner

James Michael Patterson

Perry Tsao

Werner Berns

Dale R Eagar

A light system (FIG.) is disclosed. The light system includes a plurality of series connected light emitting diodes (-). Each of a plurality of switching devices (-) has a control terminal and each has a current path coupled in parallel with a respective LED. A plurality of fault detector circuits (-) are each coupled in parallel with a respective light emitting diode. Each fault detector circuit has a first comparator (FIG.) arranged to compare a voltage across the respective light emitting diode to a respective first reference voltage (). When a fault is detected, a control signal is applied to the control terminal to turn on a respective switching device of the plurality of switching devices.

LED bypass and control circuit for fault tolerant LED systems

A light system (FIG.) is disclosed. The light system includes a plurality of series connected light emitting diodes (-). Each of a plurality of switching devices (-) has a control terminal and each has a current path coupled in parallel with a respective LED. A plurality of fault detector circuits (-) are each coupled in parallel with a respective light emitting diode. Each fault detector circuit has a first comparator (FIG.) arranged to compare a voltage across the respective light emitting diode to a respective first reference voltage (). When a fault is defected, a control signal is applied to the control terminal to turn on a respective switching device of the plurality of switching devices.

A system includes a first transistor configured to control a current through one or more LEDs and an inductor coupled in series with the one or more LEDs. The system also includes a current mode switcher configured to control the first transistor so that the inductor has a substantially constant ripple current. The system may further include a resistor and a second transistor coupled across the one or more LEDs and an integrating capacitor coupled in series with the second transistor. The switcher may include a driver configured to drive the first transistor to turn the first transistor on and off. The switcher may also include a detector configured to turn off the first transistor when a current through the first transistor exceeds a first threshold. The switcher may further include a timer configured to turn on the first transistor when a voltage on the integrating capacitor exceeds a second threshold.

Current mode switcher having novel switch mode control topology and related method

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Longmont, CO, United States of America

Joseph V DeNicholas