Search results
Results From The WOW.Com Content Network
Secondary breakdown is a failure mode in bipolar power transistors. In a power transistor with a large junction area, under certain conditions of current and voltage, the current concentrates in a small spot of the base-emitter junction. This causes local heating, progressing into a short between collector and emitter.
Current mode logic (CML), or source-coupled logic (SCL), is a digital design style used both for logic gates and for board-level digital signaling of digital data.. The basic principle of CML is that current from a constant current generator is steered between two alternate paths depending on whether a logic zero or logic one is being represented.
One style of current limiting circuit is shown in the image. The schematic represents a simple protection mechanism used in regulated DC supplies and class-AB power amplifiers. Q1 is the pass or output transistor. R sens is the load current sensing device. Q2 is the protection transistor which turns on as soon as the voltage across R sens ...
A resistor removed from a high voltage tube circuit shows damage from voltaic arcing on the resistive metal oxide layer. Resistors can fail open or short, alongside their value changing under environmental conditions and outside performance limits. Examples of resistor failures include: Manufacturing defects causing intermittent problems.
Snapback is a mechanism in a bipolar transistor in which avalanche breakdown or impact ionization provides a sufficient base current to turn on the transistor. It is used intentionally in the design of certain ESD protection devices integrated onto semiconductor chips.
A different form of short-circuit testing is done to assess the mechanical strength of the transformer windings, and their ability to withstand the high forces produced if an energized transformer experiences a short-circuit fault. Currents during such events can be several times the normal rated current.
Generally this means that high current circuits such as on chip power regulators use metal–oxide–semiconductor field-effect transistors (MOSFETs) for efficient control, and 'sea of logic' use conventional CMOS structures, while those portions of specialized very high performance circuits such as ECL dividers and LNAs use bipolar devices.
A transient-voltage-suppression diode can respond to over-voltages faster than other common over-voltage protection components such as varistors or gas discharge tubes. The actual clamping occurs in roughly one picosecond, but in a practical circuit the inductance of the wires leading to the device imposes a higher limit. This makes transient ...