AN2986 Datasheet, PDF (1/18 Pages) STMicroelectronics – This document focuses on the calculation

AN2986
Application note
AC switch triggering with 3.3 V power supply
Introduction
This document focuses on the calculation of gate current consumption of various types of
AC switches when using a 3.3 V power supply. Until now, the standard of a 5 V power supply
was used. In home appliance applications there is a bigger focus on the MCU working with
a 3.3 V power supply, and a lower supply voltage brings additional constraints on gate
circuitry. This application note provides a precise calculation process in order to correctly set
the necessary parameters.
This application note concerns Q2 and Q3 operation (i.e. for negative power supply) as this
is the most common mode of operation for AC switches, but advice and comments for
operation in Q1 and Q4 quadrants (i.e. for positive power supply) are also given.
July 2009
Doc ID 15727 Rev 1
1/18
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