Gate to cathode capacitor, impact on dI/dt capability

AN4030

12/15

Doc ID 022635 Rev 1

Figure 9.

Sequence of events during Triac switch-on in quadrant 2

Even if the Triac is driven in zero voltage switch mode, a spurious turn-on could appear and

a high dI/dt could run through pilot SCR. A gate to cathode capacitor could increase the

failure rate as explained above. For example, for the sensitive logic level Triac described in

Section 1.4, non repetitive dI/dt capability robustness in Q2 is divided by around 2 with a

cathode capacitor.

This behavior is not linked to the Triac technology but directly linked to the internal device.

So, whatever the technology, a gate to cathode capacitor will decrease dI/dt capability in

repetitive or in accidental mode.

N3

P2

N2

P1

N1

P2

N2

P1

A2

A1

G

-

++

I G

I

T

I C

CGK

R

G

1

2

4

3

N4