This disclosure is directed to circuits and techniques for protecting a power switch when the power switch is turned ON. A driver circuit may detect whether the power switch is in a desaturation mode or an overcurrent state based on a signal at a detection pin, and disable the power switch in response to detecting that the power switch is in the desaturation mode or the overcurrent state. In addition, the driver circuit may detect whether the power switch is trending towards a safe operating area (SOA) limit of the power switch based on a rate of change of the signal, and disable the power switch in response to detecting that the power switch is trending towards the SOA limit.

An amplifier overload power limit circuit, system, and a method thereof comprising a monitoring of a current gain of a BJT based on a current detector and limiting power to the BJT based on the monitored current gain to prevent the BJT from driven into a saturation mode and the amplifier overdrive.

The present disclosure relates to an electronic valve apparatus for a high voltage direct current, HVDC, power transmission system. The electronic valve apparatus comprises a first device chain (301) including a plurality of first devices (302, 303) connected in series between an input node (330) and an output node (332) of the electronic valve apparatus (300, 400, 500). Each of the plurality of first devices (302, 303) has an asymmetric transfer function configured substantially to block current flow through the device in a first direction, and the plurality of first devices (302, 303) are connected such that they all block current flow in the same direction. The electronic valve apparatus also includes a second device chain (311) including a plurality of second devices (312, 313) connected in series between the input node (330) and the output node (332). Each of the plurality of second devices (312, 313) has an asymmetric transfer function configured substantially to block current flow through the device in a first direction, and the plurality of second devices (312, 313) are connected such that they all block current flow in the same direction. The second device chain (311) is connected in parallel with the first device chain (301).

A method for protecting a power switch during turn-on includes sensing that a change in current through the power switch is in regulation, measuring a time the change in current through the power switch is in regulation, and comparing the time the change in current through the power switch is in regulation to a reference time. An over current signal, which can be used to disable the power switch, is generated if the time the change in current through the power switch is in excess of the reference time.

Support circuitry for a power transistor includes a feedback switching element and switching control circuitry. The feedback switching element is coupled between a Kelvin connection node and a second power switching node. The switching control circuitry is configured to cause the feedback switching element to couple the Kelvin connection node to the second power switching node after the power transistor is switched from a blocking mode of operation to a conduction mode of operation and cause the feedback switching element to isolate the Kelvin connection node from the second power switching node before the power transistor is switched from the conduction mode of operation to the blocking mode of operation.

An igniter includes a switch element with input, output control electrodes, a first lead in contact with the input electrode and connected to a primary coil of an ignition coil, a second lead that is grounded, a third lead spaced apart from the first and second leads, a first bonding wire connecting the output electrode and the third lead, a second bonding wire connecting the third lead and the second lead, and a control IC that drives the switch element based on an ignition instruction signal from an engine control unit. The control IC generates an ignition confirmation signal based on the voltage of the third lead, and outputs the signal to the engine control unit.

A power distribution system and method has a controller and at least one semiconductor switch. The power distribution system additionally has an on status detector which detects the status of the semiconductor switches, and an overcurrent status circuit which checks for overcurrent conditions.

An overcurrent protection circuit is provided for a switching element turned on/off based on a control voltage. The overcurrent protection circuit includes a first transistor and a second transistor. The first transistor is a PNP bipolar transistor and has an emitter connected to the control voltage. The second transistor is an NPN bipolar transistor and has a base connected to a collector of the first transistor, a collector connected to a base of the first transistor and pulled up to a predetermined pull-up voltage, and a grounded emitter. When the control voltage exceeds a predetermined first threshold voltage, the first and second transistors are turned on, the control voltage is dropped by drop of the pull-up voltage, and thus the overcurrent protection circuit starts a protection operation of turning off the switching element.

An amplifier overload power limit circuit, system, and a method thereof comprising a monitoring of a current gain of a BJT based on a current detector and limiting power to the BJT based on the monitored current gain to prevent the BJT from driven into a saturation mode and the amplifier overdrive.

A gate drive circuit includes a driver for driving a gate of a switching element, a peak voltage detector, and a drive capacity calculator. The peak voltage detector detects a peak voltage at a main terminal of the switching element when the switching element is OFF. The drive capacity calculator calculates a voltage difference value between the detected peak voltage and an allowable voltage value at the main terminal of the switching element, where the allowable voltage is based on the specifications of the switching element. The drive capacity calculator changes a drive capacity of the driver to gradually decrease the difference between the detected peak voltage and the allowable voltage.