Abstract: Systems, methods, and devices are provided for detecting short circuits in a backlight assembly without a resistor-based current sensor. For example, an electronic display according to the present disclosure may include a display panel and a backlight assembly to illuminate the display panel. The backlight assembly may drive a backlight element to illuminate the display panel and may include backlight short-circuit detection circuitry. The backlight short-circuit protection circuitry may detect a feedback voltage associated with the backlight element and determine when a short circuit has occurred based at least in part on the feedback voltage.

Abstract: Methods and/or devices are provided for monitoring life-expectancy and/or useful life of an optical transceiver module by tracking an insertion cycle count of an optical transceiver module. An alarm/warning indicator may be generated or the optical transceiver module can be disabled completely if the insertion cycle count exceeds a predefined threshold. The host device first detects the insertion of the optical transceiver module and then reads the cycle count along with an identifier value from the non-volatile memory of the optical transceiver module. The host device then increments the insertion cycle count by one, to account for the current insertion, and stores this new cycle count into a non-volatile memory of the optical transceiver module. The insertion cycle count value may be encrypted and/or the non-volatile memory of the optical transceiver module may be password-protected to avoid accidental and/or unauthorized access to the non-volatile memory of the optical transceiver module.

Abstract: Disclosed embodiments relate to techniques for operating a backlight unit of a display device in a redundant mode and a non-redundant mode in the event of an open circuit condition or short string condition. For instance, in a redundant mode, multiple LED strings are driven to provide a first quantity of light, such that the combined output from all LED strings is capable of providing a total light output corresponding to a maximum brightness setting for the display device. In the case that one of the LED strings fails due to an open circuit condition or short string condition, the remaining LED strings may be driven to provide a second quantity of light that is greater than the first, such that the combined light output from the remaining LED strings provides the same total light output for achieving the maximum brightness setting.

Abstract: A system may include a processor, a graphics controller, and a display. The graphics controller may generate video data to be presented on the display. The display may include a display panel, a backlight unit for providing the display panel with backlight, and a display timing controller for communicating with the graphics controller. The display may be used in non-movie mode and movie mode. The backlight unit may be operated in fixed backlight mode during the non-movie display mode and may be operated in dynamic pixel backlight (DPB) mode during the movie display mode. Backlight level adjustments may be sloped only during the non-movie mode. Backlight level sloping can be handled internally within the backlight unit, can be controlled using pulse width modulation with the display timing controller, and implemented using incremental backlight level adjustments with the processor.

Abstract: Systems, devices, and methods for a shared matrix of shared row pins and/or column pins between a first array of keys and a second array of lights of a keyboard. A keyboard controller addresses the first array of keys and the second array of lights during a scanning period using the shared row pins and/or column pins. Each key is backlit by one or more lights of the second array of lights that may be individually controlled. The keyboard controller may drive the desired lights of a respective row while detecting key presses of the same row during the row interval using the shared row pins and/or column pins. In some embodiments, the keyboard controller may drive the desired lights of a row during driving interval of the row interval, and scan the keys of the row separately during a sensing interval of the row interval.

Abstract: An electronic device may be provided with display circuitry that includes a display timing controller, a backlight driver, a light source, and other associated backlight structures. The backlight control circuitry may generate a control signal having an adjustable duty cycle to the backlight driver. The backlight driver may include a boost converter, a current driver, and backlight control circuitry. The current driver may only be activated when the control signal is high. The backlight control circuitry may output an enable signal to the boost converter. The backlight control circuitry may activate the boost converter a predetermined amount of time before each rising clock edge in the control signal by asserting the enable signal for a longer period of time than when the control signal is high. The control signal and the enable signal may be deasserted at around the same times.

Abstract: Disclosed embodiments relate to techniques for operating a backlight unit of a display device in a redundant mode and a non-redundant mode in the event of an open circuit condition or short string condition. For instance, in a redundant mode, multiple LED strings are driven to provide a first quantity of light, such that the combined output from all LED strings is capable of providing a total light output corresponding to a maximum brightness setting for the display device. In the case that one of the LED strings fails due to an open circuit condition or short string condition, the remaining LED strings may be driven to provide a second quantity of light that is greater than the first, such that the combined light output from the remaining LED strings provides the same total light output for achieving the maximum brightness setting.

Abstract: A measured voltage drop across a power-line transistor is used as a sensing element to measure the current and detect an over-current condition for an LED backlight system. An over-current or short condition is detected when the measured voltage drop exceeds a threshold. Accurate detection of the over-current condition is achieved by calibrating the RDS-ON (i.e., internal resistance between drain and source, when transistor is on) of the power-line transistor. In one embodiment, the calibration of RDS-ON is performed by ramping down the threshold from an initial value and using the tripped threshold to determine the actual value for RDS-ON. In another embodiment, the calibration of RDS-ON is performed by using two thresholds, a first threshold to calibrate RDS-ON and a second threshold to detect the over-current condition.

Abstract: Disclosed embodiments relate to techniques for operating a backlight unit of a display device in a redundant mode and a non-redundant mode in the event of a shorted LED failure condition. For instance, in a redundant mode, multiple LED strings arranged in an end-to-end configuration are each driven to provide a first quantity of light, such that the combined output from all LED strings is capable of providing a total light output corresponding to a maximum brightness setting for the display device. In the case that an LED on one of the strings fails due to a shorted LED failure condition, the remaining functional LEDs of the affected string may be driven to provide a second quantity of light, such that the combined output from the affected strings and the non-affected strings may still provide the same total light output for achieving the maximum brightness setting. The second quantity of light is greater than the first quantity.

Abstract: Systems and methods for light-load efficiency in displays may include a backlight driver circuit that may adjust a gate drive voltage provided to a gate of a metal-oxide-semiconductor field-effect transistor (MOSFET) in the boost converter based on the load conditions of light-emitting diodes used to illuminate the display panel. The backlight driver circuit may also switch between two different voltage sources to further broaden a range of gate drive voltages available to drive the gate of the MOSFET in the boost converter. As a result, the backlight driver circuit may decrease gate drive losses associated with the MOSFET, thereby increasing the efficiency of the boost converter.

Abstract: Devices and methods for controlling brightness of a display backlight are provided. A display backlight controller may control the brightness of the display backlight by changing a duty cycle of a PWM signal that drives the LED current. However, because of LED efficacy and response time, the final output brightness (NITS) may not be linear between 0% to 100%. The disclosed methods may be used to correct the brightness using a predetermined correction factor. Further, the minimum and maximum duty cycle of the output dimming duty cycle may be limited or corrected. In one example, a backlight controller receives an input duty cycle and determines a product of the input duty cycle and a maximum duty cycle to produce a reduced duty cycle. Moreover, the backlight driver may determine a corrected duty cycle using the correction factor. The final output duty cycle and LED current may then be determined.

Abstract: A system and method for multiple power over Ethernet (PoE) power supply management. Power supply status signals indicative of an operating condition of a plurality of PoE power supplies are provided to a plurality of power sourcing equipment (PSE) controller chips. Pre-configured combination logic within each of the PSE controller chips converts an indicated operational state of the plurality of PoE power supplies into a powering decision for each of the Ethernet ports served by the PSE controller chip within one microsecond.

Abstract: Systems, devices, and methods for using a hot plug detect (HPD) signal to reduce turn on time of a backlight of a display are disclosed. The backlight controller may pre-charge the backlight based at least in part on receiving the HPD signal prior to receiving a BL_EN signal to turn on the backlight. The HPD signal may be a multipurpose signal used by components of a system in addition to the backlight driver. The backlight driver may turn on the pre-charged backlight immediately upon receiving the BL_EN signal. The backlight controller may maintain the pre-charge of the backlight while the device is in a sleep state to reduce the turn on time of the backlight from the sleep state. Embodiments of the HPD signal may also power down the display and backlight.

Abstract: A system and method for global power management in a power over Ethernet (PoE) chassis. Power supply status signals indicative of an operating condition of a plurality of power supplies are provided to a plurality of power sourcing equipment (PSE) controller chips in a plurality of blades of a chassis system. Pre-configured combination logic within each of the PSE controller chips converts an indicated operational state of the plurality of power supplies into a powering decision for each of the ports served by the PSE controller chip. Global power management is also effected through the use of scaling factors for the various blades to ensure that the lowest priority powered port (LPPP) in a first blade does not have a lower priority than the highest priority non-powered port (HPNPP) in a second blade.

Abstract: One embodiment of a display backlight driver integrated circuit can be configured for operation in at least two different ways. A first method transfers data from an EEPROM to hardware registers prior to regular operation. A second method also transfers data from an EEPROM to registers. However, hardware registers can be overwritten with data accepted from a control bus, prior to regular operation. A keyboard driver IC can detect the presence or absence of a cable to an LED. If the cable is absent, the driver IC will not supply power for the LED. One embodiment of a keyboard and display backlight control system can be configured to allow substantially independent operation.

Abstract: A power supply with reduced electromagnetic interference (EMI) is described. This power supply includes cascaded stages with switched-mode power-supply circuits that are switched synchronously during operation by switching signals that have a common fundamental frequency. EMI associated with the power supply is reduced by establishing a phase shift between the switching signals in at least two of the stages.

Abstract: A system and method for communicating information using Layer 1 from a powered device to power source equipment via Ethernet. In one embodiment, Layer 1 information such as power management, classification, temperature, and disconnect information is transmitted from a powered device to power source equipment using an AC signal that has a cycle defining a first time period during which the AC signal is turned on and a second time period during which the AC signal is turned off. A type of information being sent by the powered device can be determined based on characteristic on/off times of the AC signal cycle.

Abstract: Systems, methods, and devices are provided for detecting short circuits in a backlight assembly without a resistor-based current sensor. For example, an electronic display according to the present disclosure may include a display panel and a backlight assembly to illuminate the display panel. The backlight assembly may drive a backlight element to illuminate the display panel and may include backlight short-circuit detection circuitry. The backlight short-circuit protection circuitry may detect a feedback voltage associated with the backlight element and determine when a short circuit has occurred based at least in part on the feedback voltage.

Abstract: Systems and methods for inaudible enhanced pulse width modulation (PWM) backlight dimming are provided. By way of example, an electronic display backlight system according to the present disclosure may include a backlight element and backlight driver circuitry. The backlight driver circuitry may drive the backlight element at various brightness levels using at least two individual duty cycles that occur immediately after one another. The backlight driver circuitry may vary the individual duty cycles such that none will ever reach 100% unless all are 100%, thereby preventing the occurrence of audible noise that might otherwise arise if an “on” PWM period from one individual duty cycle continued into the next.

Abstract: A system and method of analyzing a powered device (PD) in a Power-over-Ethernet (PoE) system are presented. The system includes an Ethernet interface having a physical layer (PRY) chip capable of providing a signal pulse in addition to physical layer 1 functions. The system further includes a pulse transformer, coupled to the PRY chip, capable of relaying the signal pulse provided by the PRY chip to the PD via the transmit line and a second PRY chip. The first PRY chip receives one or more return pulse signals from the PD, analyzes characteristics such as voltage and/or frequency of the return pulse signal(s), and determines attributes of the PD based on those characteristics. The attributes can include powered device validity and power classification. A method of supplying power to a PD is also presented.