UM0575

Board performances

9/20

The two resistors which are mainly dissipating power at standby are:

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R2 - used to provide T2 with gate current during the e-STARTER on state

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R3 - used to sense the voltage level across the PTC

full-wave mode. R3 senses only half the voltage across the PTC and T1. This voltage is also

We can neglect the voltage drops of M1 and of C1, which are lower than 0.6 V and 16 V

respectively. The power losses, dissipated by the two resistors, are given by the following

equations:

Equation 1

An example with R2 = 470 k

Ω and R3 = 510 kΩ gives:

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The overall power losses then equal 380 mW.

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voltage, i.e at worst 115 V RMS. The overall power losses then equal 41 mW.

2.3

Fast transient voltages

Immunity tests, as described by the IEC 61000-4-4 standard, have been performed with the

schematics of Figure 5, connected in series with a compressor without a RUN or START

capacitor. e-STARTER spurious triggerings have not been detected with spikes up to 2 kV.

This high immunity level has been reached thanks to:

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the high dV/dt capability of the ACST6

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the improved dV/dt capability of the very sensitive SCR X0202M (20 µA < Igt < 50 µA)

thanks to the fact that its gate is short-circuited to the cathode via M1 in OFF state, and

also thanks to the R6-C4 snubber circuit

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provided by R2 when M1 is ON

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the immunity provided by the layout of the printed circuit board (refer to Figure 15)

It should be noted that spurious triggering of the e-STARTER is not a problem as such

behavior is not seen by the end user, and as these turn-ons do not lead to any component

failure.

2.4

Surge voltages

The ACST6 device is an overvoltage protected device which means that it can be used

without any varistor in parallel with its terminals. If a high energy surge is applied to the

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