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Design Rules for Triac Reliabilty Operation-★☆

DESIGN NOTE

DESIGN RULES FOR RELIABLE TRIAC OPERATION

1/ CORRECT TRIGGERING: To turn a triac ON, the gate drive circuit must supply an “energetic” gate current to ensure fast and efficient firing. Gate current amplitude: The gate current (IG) must be much higher than the specified maximum gate triggering current (IGTmax). This parameter is given at Tj = 25°C. For lower temperatures, use the curve which presents the relative variation of the gate triggering current versus junction temperature. Design the gate driver for the lowest expected operating temperature. A high IG value provides an efficient firing (see §2). As a practical rule we recommend: I G > 2 I GTMAX Gate circuit design: Fig. 1: Example of gate drive circuit.

VG

+VDD

Rs

+

MCU
IG

230 Vac
VOL
LOAD

Rs =
With :

V DD