Initial site 1 is characteristic very small currents at which it is possible to consider Resistance on this site is very great therefore tension happens the set size always, and current can be found on a formula (.
The bipolar transistor at inclusion it according to the scheme with the general base has the necessary directions of currents, but its coefficient of strengthening on 0 current
The origin of a negative site on the characteristic of a dinistor is caused by the same reason, as in an avalanche. Namely, at both devices on this site the direct current of base (at a dinistor it is equal to zero) is set. Therefore dIk ratio = by die, i.e. differential coefficient has to be carried out and has to be equal to unit all the time. With growth of current the size aspires, but this increase is prevented by reduction of tension on collector transition, i.e. weakening of a shock. The same conclusion follows from a formula (in which the denominator cannot be negative, and,, since some working, the increase in integrated coefficient of has to be followed by reduction of coefficient of M, i.e. an of collector tension.
Current of the return switching can be found from the equation (1 if to consider II, in case of small negative currents of base Io current, is much more than I0I current. At big currents of I this difference decreases. Io relation, p/Ií it is possible to call strengthenings at switching off; it is defined. size a1 / (and - and in usual trinistor does not exceed (. It is obvious that from the point of view of controllability when locking the total coefficient of transfer but should not be done much more big units.
At the avalanche transistor at which <1 at any current, Uk always has final size. At a dinistor at which coefficient of == + to exceed unit, U (more precisely, tension on collector transition becomes equal to zero at some final current/. At even bigger current of a formula (and (become invalid as
Recently one of bases of dinistor is alloyed usually the. The purpose of such alloying - to reduce life time and by that switching time. Thus w/L relation at the same time increases (as L = (d ), so, and coefficient that besides promotes increase of tension of switching.
Let's note that for structure r-p-r-p in general this current will represent collector current at the switched-off emitter. We will write down the sizes relating to all us to structure without indexes. Thus,
If to change polarity of tension attached to the considered structure to the return, transitions of P1 and P3 will be displaced in the opposite direction. If both of these transitions rather high-voltage, the volt-ampere characteristic has an appearance of the return branch of the usual diode characteristic.
As in this case we deal not with r-p-r, and with the transistor p-r-p, it is obvious that a of this conditional transistor has to be to which positive tension is brought, and the emitter — an electrode to which tension is brought. In other words, polarity of tension, to the conditional transistor, such is that average r-p transition has shift in the opposite direction and on is mute almost all tension of the power supply whereas right r-p transition has shift in the direct direction falls.
From here it is visible that the increase in current of Ib, so, and coefficient of 1 is followed by reduction of coefficient of 3, so, and In current. There will be also Io.p current in a point of the return switching respectively slightly less.
To weaken dependence of (I) at small (especially at germanic structures), often emitter transition by a small of R. Then the considerable part of the general current branches off in this resistance, passing the emitter. Thereby emitter current, and together with it and coefficient and with other things being equal.
Collector tension, decreasing on site 3, becomes equal to zero in a point of N (The point of N designates saturation mode border — the mode in which both emitter, and collector transitions work in the direct direction.). From a formula (at U = 0 we receive a ratio
It was noticed a bit later that characteristics of such structure in many respects reminded characteristics of tiratron, and devices of this kind received the name of tiristor (by analogy with terms and a ).