BTAB STMicroelectronics Triacs datasheet, inventory, & pricing. BTAB 12A Triacs. DESCRIPTION Available either in through-hole or surface-mount packages, the BTA/BTB12 and T12 triac series is suitable for general. DESCRIPTION. Available either in through-hole or surface-mount packages, the BTA12, BTB12 and T12 triac series is suitable for general.

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So, in the end, the structure which is crossed by the major portion of the current is the same as quadrant-I operation “3” in Figure 5. The TRIAC’s gate can be connected through an opto-isolated transistor, and sometimes a resistor to the microcontroller, so that bringing the voltage down to the microcontroller’s logic zero pulls enough current through the TRIAC’s gate to trigger it. Some of these electrons do not recombine and escape to the underlying n-region step 2.

The value of this parameter varies with:. Thus, the triggering scheme is the same as an SCR. Suppose one wants to turn the inductor off: In many cases this is sufficient to lower the impedance of the gate towards MT1. Quadrant 3 operation occurs when the gate and MT2 are vta12 with respect to MT1. Other three-quadrant TRIACs can operate with smaller gate-current to be directly driven by logic level components.

Btab Datasheet Great Triac 12a Bta12 b B6h5 | datasheet

From Wikipedia, the free encyclopedia. In particular, if the pulse width of the gate current is sufficiently large generally some tens of microsecondsthe TRIAC has completed the triggering process when the gate signal is discontinued and the latching current reaches a minimum level called holding current.

This is commonly used bta112 controlling the speed of induction motorsdimming lamps, and controlling electric heaters. For the green datzsheet, see Triac car. The relative sensitivity depends on the physical structure of a particular triac, but as a rule, quadrant I is the most sensitive least gate current requiredand datasheeet 4 is the least sensitive most gate current required. The N region attached to MT2 is active, but the N region attached to MT1 only participates in the initial triggering, not the bulk current flow.

This, however, increases the required trigger current or adds latency due to capacitor charging.

Generally, this quadrant is the most daatsheet of the four. As forward-biasing implies the injection of minority carriers in the two layers joining the junction, electrons are injected in the p-layer under the gate. As current into the gate increases, the potential of the left side of the p-silicon under the gate rises towards MT1, since the difference in potential between the gate and MT2 tends to lower: A TRIAC starts conducting when a current flowing into or out of its gate is sufficient to turn on the gta12 junctions in the quadrant of operation.


The turn-on of the device is datasbeet and starts dagasheet the current from MT1 flows into the gate through the p-n junction under the gate. In a typical TRIAC, the gate threshold current is generally a few milliamperes, but one has to take into account also that:.

In this case, the injection of holes in datasgeet p-silicon makes the stacked n, p and n layers beneath MT1 behave like a NPN transistor, which turns on due to the presence of a current in its base. Snubber circuits are also used to prevent premature triggering, caused for example by voltage spikes datasheeet the mains supply.

Retrieved June 28, Triggering in this quadrant is similar to triggering in quadrant III. The reason is that during the commutation, the power dissipation is not uniformly distributed across the device. A careful reading of the application notes provided by the manufacturer and testing of the particular device model to design the correct network is in order.

Retrieved from ” https: TRIACs may also fail to turn on reliably with reactive loads if the current phase shift causes the main circuit current to be below the holding current at trigger time.

Datasheft process happens in different steps here too. TRIACfrom triode for alternating currentis a generic trademark for a three terminal electronic component that conducts current in either direction when triggered.

The four quadrants are illustrated in Figure dagasheet, and depend on the gate and MT2 voltages with respect to MT1. A thyristor is analogous to a relay in that a small voltage and current can control a much larger voltage and current.

Solid state switches Power electronics. The current and voltage are out of phase, so when the current decreases below the holding value, the TRIAC attempts to turn off, but because of the phase shift between current and voltage, a sudden voltage step takes place between the two main terminals, which turns the device on again.

Littelfuse also uses the name “Alternistor”. In these situations it is normal to connect the neutral terminal to the positive rail of the microcontroller’s power supply, together with A1 of the triac, with A2 connected to the live. The process uses a remote gate control and is illustrated in Figure 7.



This, in turn, causes the p, n and p layers over MT2 to behave like a PNP transistor, which turns on because its n-type base becomes forward-biased with respect to its emitter MT2. When switching on, the device starts to conduct current before the conduction finishes to spread across the entire junction. Low-power TRIACs are used in many applications such as light dimmers vatasheet, speed controls for electric fans and other electric motorsand in the modern computerized control circuits of many household small and major appliances.

However, the structure is different from SCRs. Once triggered, SCRs and TRIACs continue to conduct, even if the gate current ceases, until the main current drops below a certain level called the holding current. This is similar to the recovery in standard diodes: These devices datashset made specifically for improved commutation and can often control reactive loads without the use of a snubber circuit. In other projects Wikimedia Commons. This is because it is the only quadrant where gate current is injected directly into the base of one of the main device bts12.

Capacitor types Ceramic resonator Crystal oscillator Inductor Parametron Relay reed relay mercury switch. Holding current is the minimum required current flowing between the two main terminals that keeps the datasheet on after it has achieved commutation in every part of its internal structure.

As current flows from the p-layer fatasheet the gate into the n-layer under MT1, minority carriers in the form of free electrons are injected into the p-region and some of them are collected by the underlying n-p junction and pass into the adjoining n-region without recombining.

The equivalent circuit is depicted in Figure 4. Vatasheet each SCR will have an entire half-cycle of reverse polarity voltage applied to it, turn-off of the SCRs is assured, no matter what the character of the load.

In addition, applying a trigger at a controlled phase angle of the AC in the main circuit allows control of the average current flowing into a load phase control. This in turn lowers the potential of the n-region, acting as the base of a pnp transistor which datasneet on turning the transistor on without directly lowering the base potential is called remote gate control.