Texas Instruments Corporation

National Semiconductor Corporation

Texas Instruments Incorporated Deutschland, Gmbh

James Harbison Masson

Daniel Ross Herrington

James Michael Patterson

Steven Michael Barrow

Vahid Yousefzadeh

Sumeet Prakash Kulkarni

Perry Tsao

Irwin Nederbragt

Christoph Goeltner

Werner Berns

Joseph V DeNicholas

Michael James Drake

Chi Yuen Lai

A light emitting diode system allows for high current end user LED matrix applications while mitigating internal damage to control circuitry that may be caused by excess current flow. In one example, multiple switches operate in parallel across an LED. When an overvoltage condition is detected in a first switch, a logic circuit determines those switches programmed to operate in parallel and causes them to conduct current. This reduces the amount of current flowing through any one switch and mitigates harm to the device. The parallel configuration of switches may be driven by a single pulse width modulated current. This allows the drive current to be divided between parallel transistors, limiting the damaging effects that can be caused by high currents flowing through the transistors.

Overvoltage detection circuit with first and longer second response times

Configurable switch array

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 method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, (i) identifying a pulse duty cycle by sampling at least one pulse in the sense signal and calculating a duty cycle of the at least one pulse and (ii) generating an output value identifying a duty cycle for driving one or more LEDs. The output value is based on the pulse duty cycle. The method further includes generating a holding current for the dimmer (i) during the sampling of the at least one pulse in at least one of the sampling periods and (ii) when the pulse duty cycle is less than a specified threshold. The holding current can be applied continuously when the pulse duty cycle is less than the specified threshold (such as 15%).

Dimmer decoder with low duty cycle handling for use with LED drivers

A method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, sampling a subset of the pulses in the sense signal during that sampling period. The method further includes generating a holding current for the dimmer during the sampling of the subset of pulses in at least one of the sampling periods. In addition, the method includes, for each of the sampling periods, generating an output value identifying a duty cycle for driving one or more light emitting diodes (LEDs). The subset of pulses in each of the sampling periods includes multiple pulses during that sampling period but not one or more initial pulses at a beginning of that sampling period.

Dimmer decoder with improved efficiency for use with LED drivers

Growing community of inventors

Boulder, CO, United States of America

James Harbison Masson