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AN871 APPLICATION NOTE

Figure 7. Typical circuit using triac as a bidirectional switch to control each door separately

Gate control circuit

In this circuit, the terminal A1 of the triac is sometimes connected to the ground or to the battery voltage.

Therefore, a small interface circuit is needed to drive the gate from a standard micro controller output.

This interface circuit can be done either with passive components (AC coupling with a capacitor) or with

transistor and diodes providing a direct coupling more interesting to use standard triac without particular

requirement concerning gate triggering current (see Figure 8).

RELAY

(LOCKING / UNLOCKING)

CONTROL

BUS

µCONT

INTERFACE

G1

G1

G2

G3

T1

T2

T3

M1

+Vbat.

+Vbat.

M2

M3

G2

G3