I have to replace Renasas M30853 MCU with STM32F407 MCU in a circuit. The earlier MCU uses power supply Vdd = +5V as well as all the analog and digital circuit that is connected with it. How can I use STM32F407 MCU or any of its variant to use +5V power supply?

  • \$\begingroup\$ No STM32F4 microcontrollers will work on 5V input, as far as I'm aware. You'll have to add a voltage regulator. \$\endgroup\$ – Hearth Feb 11 at 4:03
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    \$\begingroup\$ No variant uses a 5V supply for that processor... You will have to modify the supply to provide 3.3v, which may be as simple as selecting a new regulator, but it depends on the other stuff on the board and the supply circuit. \$\endgroup\$ – Ron Beyer Feb 11 at 4:08
  • \$\begingroup\$ You can't use any STM32 on 5V power, look into STR7 or NXP's catalog (former freescale) for suitable part. \$\endgroup\$ – Jeroen3 Feb 11 at 8:15

There are no STM32 parts that run on 5V, but they would work in 5V circuits. With some precautions.

Power supply

The maximum supply voltage is 3.6V, there is no way around that.

Digital I/O

All I/O pins except PA4 and PA5 (DAC outputs) are 5V tolerant in digital input or open-drain output mode.

You can connect incoming 5V digital signals directly to the I/O pins.

Digital output high level voltage is at least VDD-1.3V, that is > 2.0V at VDD=3.3V, good enough for TTL inputs.

Use an external pull-up resistor to 5V if you need output voltage above 2V, or on bidirectional signals like I2C.

Important rule: if voltages above VDD can appear on an I/O pin, then the only safe modes for that pin are digital input or open-drain output, and the internal pullup resistor should not be used.

Analog I/O

You are unfortunately on your own here, output levels must be externally amplified if necessary, input levels must be divided or clamped.


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