A light-emitting diode (LED) tube lamp and an electric leakage protection circuit are provided. The LED tube lamp. The LED tube lamp includes a leakage detecting module and a driving module comprising a Type A+B driving circuit. The leakage detecting module is connected with a power supply. The driving module is electrically connected with the leakage detecting module. The leakage detecting module detects a signal related to the output current of the power supply, and when the signal related to the output current of the power supply exceeds a reference signal, the leakage detecting module limits the current on a power loop connected to the power supply by periodically turning off a switch electrically connected to the power loop in series.

A power supply that senses the variable voltage on LED devices and uses this voltage to force current into a storage device such as a battery to charge it. When power fails, a DC-DC boost converter supplies the necessary voltage taking current from the battery to maintain the LEDs at percentage nominal current level.

A power supply that senses the variable voltage on LED devices and uses this voltage to force current into a storage device such as a battery to charge it. When power fails, a DC-DC boost converter supplies the necessary voltage taking current from the battery to maintain the LEDs at percentage nominal current level.

A boost voltage driving device is provided, in which the boost voltage driving device is electrically connected to a light emitting device, and drives the light emitting device. The boost voltage driving device includes: an electric power supply module, a microcontroller, a boost voltage module, a first feedback circuit and a second feedback circuit.

An apparatus for efficiently driving visual displays via light-emitting devices may include (1) at least one light-emitting device, (2) a buck driver circuit electrically coupled to the light-emitting device, wherein the buck driver circuit includes an inductor, and (3) a boost circuit electrically coupled between the buck driver circuit and a power source, wherein the boost circuit includes an additional inductor. Various other apparatuses, systems, and methods are also disclosed.

A light source driving circuit and a light source driving method of a display panel are provided. The light source driving method of a display panel includes: acquiring a load value for displaying a frame of an image, wherein the load value is a predetermined current value for driving a light emitting diode array of the display panel; determining whether the load value is greater than a first threshold, wherein the first threshold is 20% of a rated current of the light emitting diode array; controlling the light emitting diode array to be turned on and off based on one of a pulse width modulation signal, a pulse frequency modulation signal, and a pulse skipping modulation signal according to a determining result, such that an average current input to the light emitting diode array is the predetermined current value.

In various embodiments, a switched-mode power supply is provided. The switched-mode power supply includes at least two output stages. Each output stage has a converter. A frequency of at least one of the output stages is modulated by way of a modulation unit configured to provide a modulation signal that is combined with a switching signal for driving a switching element of the converter of the at least one output stage.

In various embodiments, a switched-mode power supply is provided. The switched-mode power supply includes at least two output stages. Each output stage has a converter. A frequency of at least one of the output stages is modulated by way of a modulation unit configured to provide a modulation signal that is combined with a switching signal for driving a switching element of the converter of the at least one output stage.

A light-emitting element driving semiconductor integrated circuit that constitutes at least a portion of a light-emitting element driving device configured to drive a plurality of light-emitting elements connected in series includes: a controller configured to have a first mode in which switching control is performed on a transistor connected in series to the plurality of light-emitting elements and a second mode in which linear control is performed on the transistor; and a first detector configured to detect that a current flowing through a sense resistor connected in series to the plurality of light-emitting elements and the transistor reaches a threshold value, wherein the controller switches from the switching control to the linear control based on an output of the first detector.

Described herein are systems and methods for operating DC-DC regulators such as LED drivers. Various embodiments herein allow a DC-DC regulator to switch between buck mode and buck-boost mode without suffering effects otherwise resulting from transient currents when switching between modes. In certain embodiments, this is accomplished by operating the DC-DC regulator in a buck-boost mode to charge a boost capacitor with a substantially constant inductor current. The inductor current is also used to control a set of switches to operate the DC-DC regulator in a buck mode to drive a load by using the capacitor as a power source.