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christophkeiner9
christophkeiner9
Associate III
November 6, 2020
Question

STM32F103RB Reset IC neccessary?

  • November 6, 2020
  • 1 reply
  • 907 views

I had an issue with a STM32F103RB connected to a poor Power Supply with slow Ramp-Up.

In this case, the CAN Peripheral was not correctly initialized.

After adding an external Voltage supervisor the Issue dissapeared.

My question: is it also possible to use the internal Voltage supervisor when i have connected the VBAT Pin to VDD?

The setting seem to be stored in the VBAT-Powered domain and therefore cleared after powering down vbat.

This topic has been closed for replies.

1 reply

waclawek.jan
waclawek.jan
Super User
November 6, 2020

The 'F103 is an old design (within STM32), but there *is* a poweron reset circuitry built in. However, there's no provision to change the poweron reset level. See datasheet for "Power on/power down reset threshold".

While the supply voltage ramps up slowly, this reset releases at a relatively low voltage level (around 2.0V) and external circuits may not be already ready to work.

The Programmable voltage detector (PVD) as described in RM (and respective voltage levels documented DS) is an entirely "software" stuff, does not impact reset. However, you may want to utilize it - after poweron reset, using PVD, wait until it indicates that power supply is already high enough.

JW

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