ST STEVAL-IHT001V1, Руководство пользователя

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Functional description UM0277
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In order to reduce the surge current, a R6 resistor is used in series with the C3 capacitor.
The power dissipation of this resistor is limited to ½ Watt. In this case, with a 30 mA output
DC average current, a 47
Ω
resistor value can be used on the board for typical application
conditions (100/230 V
RMS
line voltage and 50/60 Hz mains frequency).
Appendix G defines, in typical application conditions (nominal capacitor value, nominal RMS
line voltage), the C3 capacitor value for a 30mA output DC current versus different AC mains
and frequency values used in different countries. Moreover, the typical and minimal (nominal
capacitor value -10%, minimum RMS line voltage) output DC current capabilities are given
for information.
One particularity of the STEVAL-ITH001V1 board power supply is to be a “negative” one.
Indeed, the V
DD
terminal is connected to Neutral. This means that the GND voltage is 5V
below Neutral. Such a connection is mandatory for driving ACS devices. Indeed, ACSs can
only be triggered by a negative current (i.e. sourced from the gate).
2.4 Graphic user interface (GUI)
A Graphic User Interface (GUI) is provided to set ST7LITE39F2 Microcontroller parameters
and to access MCU information through the Serial Communication Interface (SCI). The GUI
provides the following features (refer to the “Help” menu of the GUI software for more
information):
● Sliding buttons to change MCU parameters:
– temperature hysteresis
– evaporator temperature order
– gate current pulse widths and delays
– time before defrost activation and defrost duration
– ZVS delay (synchronization of MCU commands with the mains voltage)
● Virtual graduated potentiometer to set the evaporator temperature between low,
medium or high levels
●
Virtual switch to force the loads to ON or OFF states (Light, Defrost, Compressor) for
easier board validation
● Measurement and storage of several parameters during operation (duty cycle and
running period of the compressor, evaporator temperature evolution, mains frequency
and loads status)
Table 3. Maximum output DC average currents
C3
capacitor
Max. output DC current for typical
application conditions
Max. output DC current for worst
application case
220nF 7.1mA 5.5mA
330nF 10.7mA 8.3mA
470nF 15.2mA 11.8mA
680nF 22.1mA 17.1mA
1µF 32.5mA 25.2mA
1.5µF 48.8mA 37.8mA