AN3372

ST7 microcontroller application pin use

Doc ID 018625 Rev 1

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Figure 12.

Reset circuit

The net connected to the RST pin is composed of R37 = 47 k

Ω and C16 = 100 nF. This net

is used to detect if the reference voltage has reached 5 V. The MCU gives a reset if the +5 V

level voltage is not reached.

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Pin 7: not used

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Pin 8: VDD MCU supply voltage

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Pin 9: GND

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Pin 10: not used

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Pin 11: not used

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Pin 12: GND

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Pin13: VDD MCU supply voltage. It is obtained using the Vref pin of the L6382D5 and

is able to supply 5 V with ± 2% of tolerance

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Pin 14: MCU analogue input channel 0 used for PFC Vout measurement. A resistor

divider is connected at the PFC output in order to obtain the feedback signal. It is

designed to obtain a voltage compatible with 5 V MCU voltage.

The net for Vbus measurement is shown in Figure 13.