AN436 APPLICATION NOTE

6/9

TYPICAL APPLICATION EXAMPLE

Figure 8. Typical application diagram.

The D2 transil diode protects the triac against overvoltages (see "Protection of triacs and their control cir-

cuits" in the "Thyristors and Triacs Application manual").

The RC circuit across R1 allows an increase in the current in the transformer at the beginning of the pulse.

When C is charged the resistance R1 limits the current through the transistor.

The gate current is given by the following formula (without RC).

Figure 9. Equivalent diagram

Where: tp is the pulse duration.

R

C

R1

D1

D2

220V

LOAD

+U

BZW04-376BT

SNUBBERLESS

TRIAC

U N2/N1

2

2

I

G

V

GK

V

F

–

()tp

L

P

N2

N1

--------





2

-----------------------------------

V

GK

V

F

U

N2

N1

--------





2

+

–

R

P

R1

+

() N2

N1

--------





2

----------------------------------------------------

+

=