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PCama.1
Associate III
October 11, 2021
Solved

How to get 5V supply from STSPIN32G4

  • October 11, 2021
  • 2 replies
  • 1669 views

Going over the application notes, I see that VCC provides many option but with minimum of 8V (default). I need 5V to supply my encoder and the line driver.

Should I just use a voltage divider to VCC and get my 5V out of it? Sorry if I am answering my own question, but I want to make sure. Should I also filter the power with capacitors? Any suggestions will be appreciated.

0693W00000FC9ZnQAL.png

This topic has been closed for replies.
Best answer by Enrico Poli

Hello @PCama.1​ ,

You are right, the VCC buck regulator is not able to generate a 5 V supply voltage.

Voltage divider is not the right way to obtain a supply voltage because the output of the divider strongly depends on the consumption of the connected circuitry.

One of the easiest way to obtain a regulated voltage is though a Zener diode and a BJT as shown below:

0693W00000FCENiQAP.pngThe 5.6 V Zener sets the reference voltage for the emitter follower.

The key points are:

  • R1 must be tuned to provide the right bias current to the Zener
  • Rout guarantees a minimum load current making the circuit stable

However, I would recommend a cheap linear regulator as the L78L or the LM217L.

They provide a cost-effective and compact solution for a reliable supply voltage generation.

One important point: the current consumption of the 5 V will contribute to the overall buck output current, so take care not exceeding regulator limit.

2 replies

Enrico Poli
ST Employee
October 12, 2021

Hello @PCama.1​ ,

You are right, the VCC buck regulator is not able to generate a 5 V supply voltage.

Voltage divider is not the right way to obtain a supply voltage because the output of the divider strongly depends on the consumption of the connected circuitry.

One of the easiest way to obtain a regulated voltage is though a Zener diode and a BJT as shown below:

0693W00000FCENiQAP.pngThe 5.6 V Zener sets the reference voltage for the emitter follower.

The key points are:

  • R1 must be tuned to provide the right bias current to the Zener
  • Rout guarantees a minimum load current making the circuit stable

However, I would recommend a cheap linear regulator as the L78L or the LM217L.

They provide a cost-effective and compact solution for a reliable supply voltage generation.

One important point: the current consumption of the 5 V will contribute to the overall buck output current, so take care not exceeding regulator limit.

PCama.1
PCama.1Author
Associate III
October 12, 2021

Thank you so much @Enrico Poli​ This is a great answer and very helpful. I will follow your suggestion.

Paulo