UM0277 datasheet(18/32 Pages) STMICROELECTRONICS

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Getting started

UM0277

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measured to switch ON the TRIACs which controls the Light Bulb and the Defrost resistor is

approximately 130µs for the AC mains negative cycle (230 VRMS 50 Hz line). The maximum

delay measured to switch ON the compressor is approximately 170µs for the AC mains

negative cycle (see Figure 12).

Figure 12.

Gate current pulses

3.5.3

Force debug

The Force Debug tab is used to force the AC loads state regardless of the control state

defined by the MCU for easier board validation (Figure 13). In order to control these AC

Loads, it is necessary to click the “Debug Mode” button. In this case, the green lights of the

AC Loads buttons are ON, if the associated loads are also ON, otherwise:

●

Clicking the “Compressor” button will turn on Q1, and then the compressor is running.

●

Clicking the “Bulb” button will turn on Q2, and then the light bulb is lit.

●

Clicking the “Defrost” button will turn on Q3, and then the defrost resistor is heating.

Note:

The Defrost and Compressor cannot be switched ON at the same time. Setting Defrost

resets Compressor, and vice-versa.

In order to return to “Normal” mode, click the “Debug Mode” button. In this case, all the

green lights turn off.

UM0277 Datasheet(PDF) 18 Page - STMicroelectronics