Infineon Technologies Ag

Infineon Technologies Austria Ag

Marco Pamato

Maurizio Galvano

Damiano Sartori

Franco Mignoli

Hans-Peter Kreuter

Fabrizio Cortigiani

Gernot Unterweger

Andrea Logiudice

Enrico Tonazzo

Aurelio Pellegrini

Alfonso Nasciuti

Roberto Guerra

A controller circuit for a set of light emitting diodes (LEDs) includes a linear current source, channel circuitry, and supervisor circuitry. The linear current source is configured to regulate a first current from a supply along a first series path to the set of LEDs. The channel circuitry is configured to control a second current from the supply along a second series path to the set of LEDs, the second series path being in parallel with the first series path and the second series path comprising a drop element coupled in series with the supply and the set of LEDs. The supervisor circuitry is configured to regulate a total current supplied to the set of LEDs using the linear current source and the channel circuitry, the total current comprising the first current and the second current.

Power offloading for linear current source

This disclosure includes systems, methods, and techniques for detecting one or more short connections in a plurality of light-emitting diode (LED) channels. For example, a circuit includes processing circuitry configured to control a plurality of driving devices in order to cause a pair of LED channels of the plurality of LED channels to operate in a first state during a first period of time and operate in a second state during a second period of time. Additionally, the processing circuitry is configured to compare a first electrical signal corresponding to the first state of the pair of LED channels and a second electrical signal corresponding to the second state of the pair of LED channels and determine, based on the comparison of the first electrical signal and the second electrical signal, if a short connection exists between the pair of LED channels.

Detecting short connections in a plurality of LED channels

A method and an electronic circuit are disclosed. The method includes detecting at least one operating parameter in an electronic circuit that includes a monitored LED string; adjusting a voltage threshold based on the at least one detected operating parameter; detecting a string voltage across the monitored LED string; comparing the string voltage with the voltage threshold; and detecting a defect in the LED string based on the comparing.

Method for detecting a defect in an LED string and electronic circuit with at least one LED string

An electronic circuit and a method are disclosed. The electronic circuit includes an LED circuit, wherein the LED circuit () includes: an input () configured to receive an input voltage (V); a drive circuit (A) connected to the input (); and an LED module (A) connected to the drive circuit (A) and comprising an LED string () with at least one LED. The drive circuit (A) is configured to monitor the LED module (A) for the occurrence of an LED short in the LED string () and to change from a normal mode to a defect mode upon detection of the LED short, and the drive circuit (A) is configured, in the defect mode, to operate the LED string () in at least one defect cycle that includes deactivating the LED string () for a deactivation period, activating the LED string for an activation period, and checking for the persistence of the LED short in the activation period.

Electronic circuit with an LED module

The disclosure is directed to a circuit that may detect a single short in a chain of loads, such as light emitting diodes (LEDs). The circuit may drive either multiple LED chains or a single LED chain to determine whether one, or more, of the LEDs in the LED chain is no longer working because of a short. The circuit determines whether the LED chain voltage satisfies a threshold based on a single LED voltage drop. Therefore, the same circuit may be used for applications regardless of the number of LEDs in an LED chain. Additionally, the circuit, according to the techniques of this disclosure may use may use no output pins, other than those used to deliver current to LED chains, regardless of the number of LED chains that the circuit drives.

Detection of single short-LED in LED chains

An embodiment method for short-circuit detection includes determining a set of local reference voltages each associated with a respective load chain in a plurality of load chains, and determining a global reference voltage in accordance with the set of local reference voltages. The method also includes determining, for each load chain in the plurality of load chains, a respective per-chain reference voltage in accordance with the global reference voltage, and comparing, for each load chain in the plurality of load chains, the respective per-chain reference voltage relative to a respective measured voltage across each load chain to determine a respective short-circuit condition.

System and method for short-circuit detection in load chains

In one example, a method includes generating, by a current source of a device, a first portion of a power signal that drives one or more load elements. In this example, a second portion of the power signal is generated by one or more components that are external to the device and are in parallel to the current source such that the second portion of the power signal does not flow through the current source.

Reducing power dissipation in driver circuits

Techniques are disclosed for regulating the temperature of a plurality of light-emitting diodes (LEDs) by monitoring the voltage drop across the LEDs. In one example, a driver circuit supplies a constant driver current to the LEDs. A temperature regulation circuit monitors the voltage drop across the LEDs to determine whether the junction temperature of the LEDs exceeds a maximum operating temperature. If the junction temperature of the LEDs exceeds the maximum operating temperature, the temperature regulation circuit uses digital pulse-width modulation (DPWM) to decrease a digital duty cycle of the driver current supplied to the LEDs.

Temperature protection circuit for light-emitting diodes

A method and circuit are described in which a maximum voltage is determined from among a plurality of series load voltages, where each series load voltage of the plurality of series load voltages is a voltage defined by a corresponding series of N loads of a plurality of series of N loads, where N is an integer greater than one. Also, a minimum voltage may be determined from among the plurality of series load voltages. Next, the maximum voltage from among the plurality of series load voltages may be compared with the minimum voltage from among the plurality of series load voltages to make a determination as to whether the maximum voltage from among the plurality of series load voltages exceeds the minimum from among the plurality of series load voltages by a threshold voltage. Then, an indication can be output based on the results of the determination.

Single LED short detection in multichannel LED

During a start-up phase, each corresponding test current is delivered to a corresponding chain of loads of a plurality of chain of loads. Each chain of loads is coupled between a common node and a corresponding output node. Each chain of loads includes N series-coupled loads, where N is an integer greater than one. A maximum voltage is determined from among the output voltages, where the output voltages are the voltages at the output nodes. Also, a minimum voltage is determined from among the output voltages. The maximum voltage from among the output voltages is compared with the minimum voltage from among the output voltages to make a determination as to whether the maximum voltage exceeds the minimum voltage by a threshold. An indication is output based on a result of the determination.

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Schio, Italy

Marco Pamato