supply power from Nucleo STM32G4

[Jad]

Good morning.

I am wiling to use the STM32G4 Nucleo-32 board (MB1430) board for an analog to CAN use.

 

I would like to know if I could power up my 10 5V sensors. so i would like to know if I can use the +5V of my board and the current capacity of it to power up my sensors.

 

My other question would be around the power supply of the board, It seems logical to use 7V and 800 mA to power it up so I will have as much power possible to use my 5V for my sensors. Is it the correct way to think?

 

I would also like to know if i Have a 14 Volt battery, if I can directly put 2 boards in serial, the regulator inside of them making always sure that the tension is stable even if there is current variation in the circuit.

[Andrew Neil]

---

@Jad wrote:

 power up all my sensors from my MCU.

---

Note that the MCU (the microcontroller) is just the STM32 chip - not the Nucleo board.

So far, we've been addressing powering your sensors from the Nucleo board.

Powering your sensors from the STM32 itself is another question ...

[Jad]

excuse me, I was using the term MCU but I meant Nucleo Board, for me the chip can't power 11 sensor. I wanted to use the regulators of my Nucleo board to power up my sensors. this would save me getting more regulators to my circuit.

[Andrew Neil]

---

@SofLit wrote:

What do you mean by that?

---

@Jad wrote:

 I put 2 boards in serial. 

---

I think it's better to plot a sketch 

---

Indeed. As they say, a picture is worth a thousand words!

This is particularly true in engineering (including electronics), where trying to describe systems in text alone is difficult at the best of times - and even worse when there's a language barrier.

I'm guessing that "2 boards in serial" means that they are wired in series across the 14V supply:

I don't think that will work: the 7V just specifies the the voltage applied to the board's input - it does not mean that the board will drop a constant 7V!

This can be seen by the fact that the board can be supplied with up to 12V - see Table 5 again.

And that's before you consider the issues that the 2 boards will have different GND potentials ...

[SofLit]

---

@Andrew Neil wrote:

And that's before you consider the issues that the 2 boards will have different GND potentials ...

---

Mostly when there are some links between the boards, GPIOs connection, communication .. etc 

I should not recommend that kind of power structure. 

[Jad]

ok, I do understand the issue of having two nucleos in series. I wanted to do this to use the least current possible from my battery, but now I guess the best thing to do is to connect all my Nucleos in parallel. For the calculation of the MCU power consumption, can't I have any information on it before testing it in real life with the jumpers? knowing this would permit me to know how much I have left for my sensors. Thank you again for the help

[Andrew Neil]

There should be current consumption details in the datasheet.

[SofLit]

This is what you are trying to do: 

The current i depends on the loads on regulator 1 (reg1) and regulator 2 (reg2) outputs i.e. i1 and i2. Suppose i2 changes, i changes and risks to disturb the current on reg 1 output (i1) and vice versa.. -> risk of bad regulation.