In electronics, two anti-parallel or inverse-parallel devices are connected in

parallel Parallel is a geometric term of location which may refer to: Computing * Parallel algorithm * Parallel computing * Parallel metaheuristic * Parallel (software), a UNIX utility for running programs in parallel * Parallel Sysplex, a cluster of IBM ...

but with their polarities reversed. One example is the TRIAC, which is comparable to two thyristors connected back-to-back (in other words, reverse parallel), but on a single piece of

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

. Two

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

s can be paired this way, so that each protects the other from reverse voltage. A series string of such pairs can be connected to AC or DC power, with an appropriate resistor. Some two-color LEDs are constructed this way, with the 2 dies connected anti-parallel in one chip package. With AC, the LEDs in each pair take turns emitting light, on alternate half-cycles of supply power, greatly reducing the

strobing Jerkiness, sometimes called strobing or choppy, describes the perception of individual still images in a motion picture. Motion pictures are made from still images shown in rapid sequence. Provided there is sufficient continuity between the imag ...

effect to below the normal flicker fusion threshold of the

human eye The human eye is a sensory organ, part of the sensory nervous system, that reacts to visible light and allows humans to use visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm. ...

, and making the lights brighter. On DC, polarity can be switched back and forth so as to change the color of the lights, such as in Christmas lights that can be either white or colored. Battery-powered lights, which are wired in parallel, can also create a simulated "chasing" effect by alternating the polarity for each LED attached to the string, and controlling the positive and negative parts of the cycle separately. This creates two "virtual circuits", with odd-numbered LEDs lighting on positive polarity and even-numbered ones on negative polarity, for example. By eliminating the need for extra wires, this reduces costs for the manufacturer, and makes the cords less bulky and obvious for the consumer to string on decorative items. On cheaper sets, this causes strobing and prevents any of the LEDs from getting to full brightness, since both polarities share the same wire pair and cannot be active at the same time, meaning each can only be on during its own half of the cycle. Better lights can adjust the

duty cycle A duty cycle or power cycle is the fraction of one period in which a signal or system is active. Duty cycle is commonly expressed as a percentage or a ratio. A period is the time it takes for a signal to complete an on-and-off cycle. As a formu ...

so that any unused "off" time on one polarity can be used by the other, reducing the strobing effect and making it easier to create color blends (such as orange, amber, and yellow from a red/green LED).

ESD

Antiparallel diodes are often used for ESD protection in ICs. Different ground or supply domains at the same potential or voltage may be wired separately for isolation reasons. However, during an ESD event across the domains, one would want a path for the high current to traverse. Without the antiparallel diodes in place, the voltage induced by the ESD event may result in the current following an unknown path that often leads to damage of the device. With the diodes in place the current can travel in either direction.

References

* https://www.researchgate.net/post/Why_are_diodes_connected_anti-parallel_across_the_MOSFET_or_IGBT_in_Inverter_Module * https://www.utdallas.edu/~torlak/courses/ee3311/lectures/lecture3.pdf * https://ieeexplore.ieee.org/document/4159554/ * https://www.scientific.net/AMR.328-330.32 Electronic circuits {{electronics-stub

ESD

See also

References